ASME Conference Presenter Attendance Policy and Archival Proceedings

2016;():V002T00A001. doi:10.1115/IMECE2016-NS2.

This online compilation of papers from the ASME 2016 International Mechanical Engineering Congress and Exposition (IMECE2016) represents the archival version of the Conference Proceedings. According to ASME’s conference presenter attendance policy, if a paper is not presented at the Conference by an author of the paper, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.

Commentary by Dr. Valentin Fuster

Advanced Manufacturing: Advanced Machining and Finishing

2016;():V002T02A001. doi:10.1115/IMECE2016-65434.

The inspiration for developing this atomic model comes from Merchant’s models for studying chip strain and shear angle. In this paper the 2D Merchant’s Diagram of Circles has been replaced by atoms of the workpiece and tool. This research reveals that atom losing electrons in workpiece is common in metal cutting. Also at the atomic level, cutting workpiece leads to an electric process to occur, which valence electrons leave atoms of the workpiece material as cutting tool pushing forward, forming a charged zone in the workpiece which weakens its strength and eventually causes them to be removed as cutting chip. In this paper, the charged zone was calculated for cutting 1040 steel with a tungsten carbide tool. Experimental results of electromotive force are presented to support the existence of an electrical charge in metal cutting.

Commentary by Dr. Valentin Fuster
2016;():V002T02A002. doi:10.1115/IMECE2016-65974.

The ball end magnetorheological finishing (BEMRF) is an advanced nanofinishing process for flat, curved and freeform surfaces of ferromagnetic as well as diamagnetic materials. While finishing copper (diamagnetic material) by this process, a low finishing effect is obtained as its surface repels the externally applied magnetic field. In this work a magnetic simulation is carried out over both copper and ferromagnetic material. For the ferromagnetic material the simulation result shows a high flux density region below the tool tip. However in case of copper the magnetic flux density is too low for finishing. It is also observed through simulations that when copper workpiece is placed on a mild steel base the flux density improves marginally. This led to the idea of using a permanent magnet (in place of mild steel) as a base for finishing of copper using the BEMRF process. Using this technique copper was finished and the experimental results indicate that this method can realize ultra-precision finishing of copper.

Topics: Copper , Finishing
Commentary by Dr. Valentin Fuster
2016;():V002T02A003. doi:10.1115/IMECE2016-66035.

Composite machining is one of the hot researches currently, and optimal cutting parameters are particularly important to get ideal surface and reduce processing cost of workpiece. By comparison, the present paper selects the surface root mean square deviation Sq as the three-dimensional evaluation parameter of surface roughness to reflect the special appearance after cutting accurately. The single-factor experiment and orthogonal experiment were conducted to study the machining defects emerged and effect of parameters on surface roughness when side milling CFRP (Carbon Fiber Reinforced Plastics) with diamond coated carbide tool. The mapping relationship between cutting parameters and surface roughness was established based on the experiment results. Then, the cutting parameters were optimized by using genetic algorithm with two conflicting objectives: material removal rate and surface roughness. The experiment results show that the proposed method is feasible and effective, and can provide references for the actual processing of CFRP.

Commentary by Dr. Valentin Fuster
2016;():V002T02A004. doi:10.1115/IMECE2016-66154.

Gear milling is one of the common gear manufacturing processes. In gear milling, the cutting edge of the cutting tool has an identical profile with the profile between gear teeth, and the cutting tool travels along the axial direction of the gear blank to produce the gear tooth by tooth. Due to the high requirements about the dimensional accuracy and the surface roughness during the gear manufacturing process, it is very crucial to understand the influences of cutting conditions on those requirements to improve the quality of the product and increase the production rate. In this study, a machined gear blank made from 1018 cold-rolled steel was subjected to variable speed and feed-rates in a traditional milling operation using a standard gear-milling cutter. The effect of the variable speed and feed-rates were analyzed by measuring the total lead (helix) error, total profile (involute) error, and surface finish of each gear tooth subjected to the variable cutting conditions. The objective is to experimentally investigate the correlation between the cutting conditions, i.e. cutting speed and feed, with the accuracy and quality of the machined surface during the gear milling process.

Commentary by Dr. Valentin Fuster
2016;():V002T02A005. doi:10.1115/IMECE2016-66289.

Bulk metallic glass (BMG) is an amorphous alloy. Thus, it does not have anisotropy and material defect due to its irregular atomic configuration. In addition, it has excellent mechanical properties. For these reasons, the BMG is expected to be substitute materials in various fields. Until now, a number of studies focusing on precise forming have been carried out. However, if the part geometries are complex, controls of the temperature and wettability are difficult. Therefore, single point diamond cutting of the BMG is needed to produce fine surfaces. However, only a few studies on the single point diamond cutting for the BMG have been reported. Thus, appropriate single point diamond cutting technique of the BMG is not established yet.

Therefore, single point diamond turning of Zr-based bulk metallic glass was conducted. In the paper, the influences of the depth of cut, feed rate and cutting atmosphere on the chip generation and finished surfaces are investigated. Visualization of the cutting chip generation with different cutting conditions was made with a high-speed camera. The influences of the cutting conditions on the finished surface are considered based on the observation and the measurement of chip and machined surfaces.

Commentary by Dr. Valentin Fuster
2016;():V002T02A006. doi:10.1115/IMECE2016-66341.

Surface textures helps in controlling the tribological, optical, mechanical, and thermal properties on the surfaces. The recent advancements in precision machining, makes it possible to generate micro/nano patterns on the surfaces with high dimensional control. In the present work an attempt has been made to reduce the thrust force and torque developed during drilling super alloy, Ti-6Al-4V by creating micro dimples on the tool surfaces. Circular dimples having an average diameter of 35 micrometer were created on the flute and margin side of the drill bit using Nd:YAG laser. Scanning electron microscopy analysis has been done to evaluate the quality of generated micro dimples. Drilling experiments were carried out on the titanium alloy in both dry and wet conditions using flute textured, margin textured and non textured tool for understanding the effect of micro textures on the tool. From the force analysis it was observed that in both dry and wet conditions there was a considerable reduction in thrust force and torque. Surface inspections of the drill bit were performed using Stereomicroscope for investigating the titanium buildup on the cutting tool surfaces. Results showed that the margin textured tool performed better than the flute textured and untextured tool in both dry and wet conditions.

Commentary by Dr. Valentin Fuster
2016;():V002T02A007. doi:10.1115/IMECE2016-66446.

Recently, various precision products such as lenses or mirrors are produced by the ultra-precision machine tools. Then, the single-point diamond cutting is mainly carried out using the ultra-precision machine tool. In order to generate the high accuracy and high quality machined surfaces, the high stiffness and precise rotational accuracy of the spindle is required for the ultra-precision machining tools.

The water driven spindle had been developed for the precision machine tool spindle. This spindle is driven by the generated torque due to the water flow power. Then, the rotational speed can be controlled by the supplied flow rate of water. In addition, the spindle has the water hydrostatic bearings that achieve the high bearing stiffness and precise motion accuracy. Furthermore, it is expected that the water driven spindle has the high thermal stability since the water with low viscosity is used as a coolant media.

If the thermal deformation of the spindle is caused during the machining process, the deformation degrades the machining accuracy, accordingly. Thus, it is desirable that the thermal deformation and the temperature change of each part of the spindle and machine tool structure can be controlled and minimized during machining process.

In this paper, in order to investigate the thermal stability of the water driven spindle, the measurement tests of the temperature of the water driven spindle were carried out. In addition, the power loss due to the water viscosity between the rotor and the casing of the spindle is calculated.

As a result, this paper considers the temperature change and considers the thermal stability of the water driven spindle from the results of experiments.

Topics: Temperature , Water
Commentary by Dr. Valentin Fuster
2016;():V002T02A008. doi:10.1115/IMECE2016-66574.

Reaming is one of the finishing processes that have been widely applied in manufacturing industries. Reaming of Titanium Ti-6Al-4V alloy material is an important and current research topic on manufacturing processes. Optimal process parameter setting is an important element in the machinability study of Titanium Ti-6Al-4V alloy. Optimization has most significant importance, particularly for reaming operations. This research work focuses on the multi-response optimization of reaming process parameters using the Taguchi and Grey relational technique to obtain minimum cutting temperature (T), thrust force (Ft), torque (Mt), surface roughness (Ra) and hole quality. The experiments were performed on Titanium Ti-6Al-4V alloy using uncoated carbide straight shank reamer under wet and cryogenic LN2 conditions. Eighteen experimental runs (L18) based on the Taguchi method of orthogonal arrays were performed to determine the best factor level condition. The environment, cutting speed and feed rate were selected as control factors. Grey relational analysis was used to determine the most significant control factors affecting the output parameters. Grey relational grade obtained from the grey relational analysis was used to solve the reaming process with the optimal levels of the multiple performance characteristics responses were established. The optimum results indicate that the reaming results have been improved in wet coolant than the cryogenic LN2 condition.

Commentary by Dr. Valentin Fuster
2016;():V002T02A009. doi:10.1115/IMECE2016-66584.

In this experimental work, the cryogenic cooling of the Micro-EDM (μEDM) drilling process for improving the performance and quality of micro holes. The controllable parameters such as the current (Ip), pulse on time (Ton), Pulse off time (Toff) and gap voltage (Vg) were chosen for further investigation. The Taguchi L27 orthogonal array is preferred to achieve the best experimental runs. Case hardened AISI 304 stainless steel is selected to perform the experiments. The overall machining performances of geometrical characterization such as taper angle, Overcut, Circularity at the entry and exit and the performance evaluation such as the material removal rate and electrode wear rate are analyzed. It is found that the taper angle improved by 91%, overcut improved by 17 to 66%, Circularity improved up to 70% and 68% respectively, material removal rate increased from 9 to 70% and electrode wear rate reduced up to 76%. It is found that pulse off time plays a vital role in the quality of micro holes drilled in both conventional and cryogenic micro-EDM (CμEDM) processes.

Commentary by Dr. Valentin Fuster
2016;():V002T02A010. doi:10.1115/IMECE2016-66620.

The world’s increasing demand for intercontinental mobility is leading to a steady growth in aircraft sales, with Airbus forecasting a total demand for 32,600 passenger aircraft until the year 2034. However, this demand arises not solely due to increased passenger numbers but also due to the need of replacing current aircraft as a consequence of their increasing service life. Since fuel consumption accounts for about one-third of operating costs, airlines need efficient jet engines to meet reduced noise emissions and fuel consumption demands in order to withstand international cost pressures. The development of new aircraft types focuses on the aspect of weight reduction. The aerospace industry is characterized not only by innovations in material science and technology, but also by increased integral construction of individual components for the sake of weight reduction.

Integral components are characterized by deep cavities and consist of difficult-to-cut materials to achieve weight reduction, presenting challenges for manufacturing technology. The most commonly encountered manufacturing technology for integral components is high performance cutting (HPC), using tools with a large overhang, whereby the process chain consists of two stages: roughing and finishing. However, manufacturing of integral components pushes HPC milling to its productivity limits. The interaction between work piece and end mill in the form of radial cutting forces leads to tool deflection and therefore limits the manufacturing of deep cavities. The present experimental study contributes to the analysis of tool deflection in the end milling of integral components, e.g., a blade integrated disk made of titanium for the aerospace industry.

The goal is to identify and describe tool deflection during milling and to analyze its interdependence with form deviation, as well as the local and global tool load.

A dynamometer is used to measure the global load on the tool and an experimental setup is designed and implemented to measure tool deflection and to identify the influence of the tool holder on total tool deflection. To determine tool deflection, the tool’s stiffness is determined by a reference measurement. Tool stiffness is utilized to determine tool deflection during the process and the results are illustrated for a range of technology parameters and tool wear. Tool deflection leads to a form deviation of the finished component as well as to changing contact conditions of the cutting edge, leading to increased tool wear. This study aims at providing a basic understanding of the relationship between milling force, tool deflection and form deviation under the influence of technology parameters and tool wear.

Commentary by Dr. Valentin Fuster
2016;():V002T02A011. doi:10.1115/IMECE2016-67039.

Drilling of stacks poses great challenges due the heterogeneity and abrasiveness of the composites, the chip evacuation through the stack, in addition to the difference in properties between the metallic and the composite materials. The objective of this paper is to investigate the effect of drilling conditions such as tool material and geometry and lubrication mode on the hole quality as well as the tool wear in drilling of composite stacks (Carbon Fiber Reinforced Plastics CFRP-Aluminum). The thickness of each material was 19 mm. A 2-flute uncoated drill was used. Four different cooling modes were applied namely dry, minimum quantity lubrication (MQL) with low pressure (<1.5 bar) and high flow rate (400 ml/hr), MQL with high pressure (4.25 bars) and low flow rate (10 ml/hr), and finally flood cooling. The process control parameters, namely the forces and temperatures were measured using a special fixture design using a Kistler dynamometer and a reflective system with an infrared camera. The quality of the holes was compared in terms of delamination, surface roughness, circularity, concentricity, and diameter errors. The resultant cutting forces were found to be much lower than the thrust forces. The mean forces in the Aluminum were more than double those in the CFRP. Negligible tool wear was observed (less than 60 μm). No indication of thermal damage was found on the circumference of the holes in all the tested conditions. Due to the fact that the CFRP was supported by the Aluminum stack, the exit of the holes was mostly free from delamination. The dry and flood conditions produced holes free from entry delamination, while the holes drilled with MQL had delamination within 24% of the hole diameter. Both MQL cooling modes resulted in comparable temperatures, forces and hole quality.

Commentary by Dr. Valentin Fuster
2016;():V002T02A012. doi:10.1115/IMECE2016-67064.

An analysis for a robotized grinding process of aerospace Titanium high pressure compressor blades was performed. In this process, the blade was grabbed on the robotic arm. A Scotch-Brite grinding wheel, on a pneumatic actuator, was used to grind the edges of the blades. The objective of this research work was to identify the major factors that influence the accuracy of the process and the final part quality. This objective was achieved by analyzing the dynamic characteristics of the wheel grabbed on the motor as well as analyzing the dynamic characteristics of the blade grabbed on the robotic arm. The frequency response functions (FRF) were identified at different robot configurations and positions. In addition, the vibrations of the various system components during the grinding process were monitored and analyzed to determine the effect of the speed on the relative vibrations between the workpiece and the wheel. Considering the dynamics of the wheel and the motor, rotational speed ranges were recommended. It was found that the vibrations of the grinding process were higher at two ranges: The first corresponds to the first natural frequency of the robot and the second corresponds to the first natural frequency of the wheel and the second natural frequency of the robot. By avoiding these ranges, part quality within the specified tolerances was obtained.

Commentary by Dr. Valentin Fuster
2016;():V002T02A013. doi:10.1115/IMECE2016-67136.

Fiber Metal Laminates (FML) are one of the most advanced engineered materials used in aerospace industry. The combination of metallic sheets interspersed in composite laminates in one hybrid material system provides higher impact and corrosion resistance when compared with their monolithic counterparts. However, due to the difference in machining responses for different material phases, conventional machining often induce damages and defects, affecting the cost and structural performance of the part. This research study investigates the machinability of thermoplastic Titanium Graphite (TiGr) FML. The feasibility and machinability of contouring thick (7.6 mm–10.5 mm) TiGr through Abrasive Waterjet (AWJ) process was studied in terms of machined kerf characteristics — taper ratio and surface quality. The effect of a wide range of process parameters was investigated such as geometric variables (mixing tube aspect ratio and orifice bore size), kinetic variables (water pressure, jet traverse speed) and abrasive load ratio on the machining quality. Predictive mathematical regression models were developed through Analysis of Variance (ANOVA) in order to optimize the process. Alongside, machined surface was examined to inspect the topological characteristics, material removal mechanism, and machining induced damage (micro-defects) and distortion through Surface Profilometry, Scanning electron and optical microscopy. A comparison was drawn between conventional and AWJ trimming of TiGr to demonstrate the superiority and high speed machining of AWJ with less damage.

Commentary by Dr. Valentin Fuster
2016;():V002T02A014. doi:10.1115/IMECE2016-67492.

3D Printing (Additive Manufacturing, AM) offers benefits such as lower costs, easier customization and creating complex functional products. However, utilization of AM components in the engineering applications may be severely limited by the high surface roughness. For most industrial uses the high surface roughness can cause stress concentrations, premature failure, and corrosion susceptibility. Unfortunately, conventional surface reduction processes like machining, extrude honing, and sandblasting, may not be feasible for the complex AM components. This research focused on exploring electropolishing as a viable surface smoothing approach for the AM components. However, electropolishing is a multivariable process and requires extensive parameter optimization. We have employed Taguchi’s design of experiment to find the suitable combination of electropolishing parameters. Our Taguchi analysis yielded a set of optimum experimental parameters for the electropolishing of steel AM components. This experimental process reduced the roughness of AM component surfaces as much as ∼63%.

Commentary by Dr. Valentin Fuster
2016;():V002T02A015. doi:10.1115/IMECE2016-68074.

While the blade like components of uniform thickness have been investigated for their stability in machining, impeller blade like components with varying thickness along the length and with varying width along the height have received little attention so far. Therefore, this work focuses on analyzing the effect of variation in workpiece flexibility, stiffness and rigidity on the stability of flank milling operation on impeller blade like component. Extensive experimentation was done on work specimens of (i) varying thickness along length and (ii) varying width along height. Cutting forces, acceleration and deflection of tool and work specimens were captured during all the experiments through FFT plots, chatter boundary plots followed by the stability region diagrams. The cutting force data was acquired in time domain at five different locations under varying conditions of spindle speeds and depths of cut, and were the main inputs for plotting stability region diagram. The consolidated stability region diagram shows that the stable machining, baring the few chatter peaks of low frequency and magnitude, is possible at the feed rate of 240 mm/min. and depth of cut of 1.5 mm, when the thickness as well as the width variations in the impeller blade like specimens are considered.

Commentary by Dr. Valentin Fuster
2016;():V002T02A016. doi:10.1115/IMECE2016-68134.

In multi-point operations like drilling, cutting velocities and cutting edge geometries vary along cutting lips so is the rate of progression of flank wear. Analytical evaluation of flank wear land width in the case of complex tools has received a limited attention so far. This work evaluates progression of flank wear in orthogonal machining and adopts it to drilling. An abrasive flank wear has been modeled, wherein, cutting speed determines the rate of abrasion, and the feed rate determines the chip load. The model considers stress distribution along rake surfaces, and temperature dependent properties of tool and work materials. Assuming that the flank wear follows a typical wear progression as in a pin-on-disc test, the model evaluates cutting forces and the consequent abrasive wear rate for an orthogonal cutting. To adopt it to drilling, variation in cutting velocity and, dynamic variation in rake, shear and friction angles along the length of the cutting lips have been considered. Knowing the wear rate, the length of the worn out flank (VB) has been evaluated. The model captures progression of flank wear in zones I, II and III of a typical tool life plot. It marginally underestimates the wear in the rapid wear region and marginally overestimates it in the steady-state region.

Topics: Wear , Drilling
Commentary by Dr. Valentin Fuster

Advanced Manufacturing: Computational Modeling and Simulation for Advanced Manufacturing

2016;():V002T02A017. doi:10.1115/IMECE2016-65265.

Regenerative machining chatter or resonance in the machining process has traditionally been modeled with the stability lobe approach. This paper presents a new time based direct simulation model and compares it with traditional stability lobe modeling. The direct model has the ability to discriminate directional and time information, resulting in a number of advantages over frequency-based stability lobe analysis.

Topics: Machining , Chatter
Commentary by Dr. Valentin Fuster
2016;():V002T02A018. doi:10.1115/IMECE2016-65413.

Fixture layout can affect deformation and dimensional variation of sheet metal assemblies. Conventionally, the assembly dimensions are simulated using a large number of finite element analyses, and fixture layout optimization needs significant user intervention and unaffordable iterations of finite element analyses. This paper therefore proposes a fully automated and efficient method of fixture layout optimization based on the combination of 3DCS simulation (for dimensional analyses) and GAOT, a genetic algorithm in optimization toolbox in MATLAB. The locating points, the key elements of a fixture layout, are selected from a much smaller candidate pool thanks to our proposed manufacturing constraints based filtering methods and thus the computational efficiency is greatly improved. Since MATLAB macro commands of 3DCS have been developed to calculate assembly dimensions, the optimization process is fully automated. A case study of inner hood is applied to demonstrate the proposed method. The results show that the proposed method is suitable for generating the optimal fixture layout with excellent efficiency for engineering applications.

Commentary by Dr. Valentin Fuster
2016;():V002T02A019. doi:10.1115/IMECE2016-65489.

As electronics keeps on its trend towards miniaturization, increased functionality and connectivity, the need for improved reliability capacitors is growing rapidly in several industrial compartments, such as automotive, medical, aerospace and military. Particularly, recent developments of the automotive compartment, mostly due to changes in standards and regulations, are challenging the capabilities of capacitors in general, and especially film capacitors. Among the required features for a modern capacitor are the following: (i) high reliability under mechanical shock, (ii) wide working temperature range, (iii) high insulation resistance, (iv) small dimensions, (v) long expected life time and (vi) high peak withstanding voltage. This work aims at analyzing the key features that characterize the mechanical response of the capacitor towards temperature changes. Firstly, all the key components of the capacitor have been characterized, in terms of strength and stiffness, as a function of temperature. These objectives have been accomplished by means of several strain analysis methods, such as strain gauges, digital image correlation (DIC) or dynamic mechanical analysis (DMA). All the materials used to manufacture the capacitor, have been characterized, at least, with respect to their Young’s modulus and Poisson’s ratio. Then, a three-dimensional finite element model of the whole capacitor has been set up using the ANSYS code. Based on all the previously collected rehological data, the numerical model allowed to simulate the response in terms of stress and strain of each of the capacitor components when a steady state thermal load is applied. Due to noticeable differences between the thermal expansion coefficients of the capacitor components, stresses and strains build up, especially at the interface between different components, when thermal loads are applied to the assembly. Therefore, the final aim of these numerical analyses is to allow the design engineer to define structural optimization strategies, aimed at reducing the mechanical stresses on the capacitor components when thermal loads are applied.

Commentary by Dr. Valentin Fuster
2016;():V002T02A020. doi:10.1115/IMECE2016-65684.

Thermal barrier coatings are often used to protect a component by reducing temperature excursions. Such coatings are in use on engineered products such as turbine blades. The work presented is part of a broader effort that is focusing on new and novel processing techniques for thermal barrier coatings. Manufacturing methods are being developed to create microstructures that optimize thermal protection while not degrading the mechanical properties of the coating. Sufficient mechanical properties are necessary so the coatings do not fail as a result of loadings associated with the operation of the component. One fabrication method investigated is the inclusion of spherical micron-sized pores to reflect heat radiation at high temperatures along with nano-sized grains to reflect phonons thus providing thermal protection. Pores are sized and distributed so that sufficient mechanical strength is maintained. In the current work the model material used is a yttria-stabilized zirconia (YSZ). Two-dimensional microstructures representing YSZ are computationally generated. The size and distribution of defects that have been experimentally observed to develop during bulk processing are incorporated into the computationally generated microstructural models. Heat transfer and stress-displacement analyses are performed to determine effective bulk material properties. Comparisons are made to experimental measurements available in the literature as appropriate. The influence that defect dimensions and distributions have on the effective bulk material properties are quantified as a first step understanding the impacts that micron sized pores, voids and cracks have on thermal and mechanical characteristics which will facilitate optimizing the microstructure for thermal protection and strength retention.

Commentary by Dr. Valentin Fuster
2016;():V002T02A021. doi:10.1115/IMECE2016-65993.

Subsurface deformation in orthogonal metal cutting process is nowadays widely determined by image correlation techniques. To get clearer images of the cutting process, two methods were usually adopted to reduce workpiece material side flow in the literature. One is inducing a weak inclination angle of the cutting tool; the other is to restrict material side flow by a piece of thick glass. However, the differences between the subsurface deformation determined by observing the side surfaces in these two methods and that of plane strain deformation has not been studied yet. Therefore, this paper aims to study the differences of subsurface deformation obtained by these two methods quantitatively through numerical methods. It is found that the restrict side flow method surpasses the inducing an inclination angle method; inducing an inclination angle method will produce larger discrepancy than the side surface of typical orthogonal cutting which stands for observing the side surface directly. Besides, restrict material side flow method surpasses inducing an inclination angle method in the aspect of strain distribution across the width direction. To reduce the differences further, a new method called split-workpiece method based on the bonded-interface technique is proposed in this paper. To validate the effectiveness of this method, numerical comparisons between the subsurface deformation produced by the proposed method and that of the plane strain deformation are made. The results show that the subsurface deformation produced by the proposed method is much closer to that of plane strain deformation than the previous two methods.

Commentary by Dr. Valentin Fuster
2016;():V002T02A021a. doi:10.1115/IMECE2016-66026.

Drilling is among the most significant manufacturing processes since it is widely used in the production of almost any product or part. Research in drilling processes and investigation of the phenomena that occur during the process is of great interest, given the fact that drilling is mainly applied at the final stages of the production process, thus it can greatly affect the total manufacturing cost. In the context of this study, a finite element model to simulate drilling and burr formation both on entrance and exit surface of the workpiece, was created. Simulation was implemented for the investigation of several combinations of cutting conditions, namely cutting speed and feed rate and the model was validated with a series of drilling experiments monitored by a high-speed camera.

Commentary by Dr. Valentin Fuster
2016;():V002T02A022. doi:10.1115/IMECE2016-66067.

Wire Electrical Discharge Machining (WEDM) is a versatile process to generate intricate and complex shapes on conductive work material with high dimensional accuracy and surface finish. Since the process is stochastic, its input parameters play critical role for achieving desired accuracy and precision of the component. Inconel 718, High-Strength-Temperature-Resistant (HSTR) material, has wide applications in the field of aerospace, automobile, mould making and medical industries. Hence, machining of Inconel 718 using WEDM is a challenging task. Also experimentation on Inconel 718 with WEDM is costly as well as time consuming process. Therefore to study the behavior of WEDM process with different process parameters for effective and efficient operation, process modeling and simulation using appropriate software is highly essential. In the present investigation, a 3-D single spark finite element thermal model for WEDM process has been developed using ANSYS software. This model has some more realistic assumptions like heat flux following Gaussian distribution and spark radius as a function of time and energy. Plasma incident region is meshed by keeping elemental size equal to one tenth of entire plasma radius, so that exact ten elements can be fitted. Identified elements were thermally loaded by applying element wise different temperatures for getting more accurate temperature distribution profile. This profile was found to be having crater shape matching with earlier Finite Element Models (FEM) available in the literature. Along with the shape, it also helps to decide the elements having temperatures greater or equal to melting point leading to estimate Material Removal Rate (MRR). Later on single spark MRR can be used to estimate multi-discharge-MRR by calculating pulse rate. Model MRR is validated with the experimental MRR which show a very good agreement, but little variation. This variation in the modeling could possibly due to assumptions like no delay in ignition, non-deposition of recast layer (100% flushing efficiency), etc. The factors like incomplete flushing of debris and inter-electrode gap arcing cause the variation in machining conditions thus reducing the actual MRR. In the present investigation, the use of dielectric is considered only for convection, but in reality, it acts as an insulator, coolant and also as debris remover. Melting and vaporization of material is the main phenomena for material removal. Dielectric fluid partially removes the molten metal because at the same time, the molten metal is under very high pressure due to plasma channel. Its adhesive property resists the material removal. It is very difficult to incorporate all real effects in the model, however the obtained results in the present study show good agreement between model MRR and experimental MRR within 10% variation.

Commentary by Dr. Valentin Fuster
2016;():V002T02A023. doi:10.1115/IMECE2016-66071.

Metal Matrix Composites (MMCs) give higher strength and stiffness, greater wear resistance over a wide range of conditions, making them an option in replacing conventional materials for many engineering applications. These materials are difficult-to-machine due to high hardness and abrasive nature of reinforcing elements like silicon carbide, aluminum oxide, and boron carbide particles. High tool wear and pits, cavities on machined surface due to fracturing of reinforcements puts certain constraints on MMCs for experimentation. Similarly, the experimental or analytical approaches are not able to explore the behavior of MMCs during machining due to the complex deformation and interactions with particles, matrix and tool. The numerical approach is very important tool to simulate the machining process of MMCs in which plastic deformations, modelling the plasticity are involved. FEM analysis eliminates the restrictions of experimental approach such as control of large process parameters, the exhaustive material characterization and the trial-and-error approach which is expensive and time consuming procedure to determine the mechanical responses. These advantages of finite element method make this approach more popular. It has come up as the main tool of simulation of metal cutting processes to calculate stress, strain, strain-rate, temperature distributions, tool wear, cutting forces and chip formation. In this paper, an attempt is made to present a 3D oblique finite element modelling using Deform software. In Deform, FEM analysis carried out by using steps are preprocessing, simulation and post-processing of data for the established machining process. Deform 3D is a robust simulation tool that uses the finite element model to complex machining process in three dimensions. It has been used in simulations of two types of Al/SiCp/220 MMCs with 10 and 30% of SiC reinforcement particles. These materials are considered as perfectly plastic and its shape was taken as a curved model by means of coated carbide insert as a rigid body. A simulation scheme involves size and weight fraction of reinforcement, speed, feed rate, depth of cut and preheating temperature. Four levels of speed, feed rate, depth of cut and preheating temperature are chosen. Designs of experiments are done by Taguchi’s design of experiments (DOE). For four level four parameters, suitable L16 orthogonal arrays are selected. Based on design of experiments, a machining simulation and analysis are carried out using Deform 3D, software. Obtained finite element simulation results are found to be closely match within 10 to 15% variation with the experimental results during hot machining of Al/SiCp/220 metal matrix composites (MMCs).

Commentary by Dr. Valentin Fuster
2016;():V002T02A024. doi:10.1115/IMECE2016-66447.

Reflow soldering is one of the most widespread soldering technologies used in the electronics industry. It is a method of attaching surface components to a circuit board with solder paste. The goal of the reflow process is to melt the solder and heat the adjoining surfaces, without overheating and damaging the electrical components. In the present study, computational fluid dynamics (CFD) was used to investigate the convection flow field during the cooling reflow process stage. The convection heat-transfer coefficient and temperature distribution within the board level were also studied. The analysis comprises three main objectives: (1) the simulation of the cooling process of a PCB in the final section of the reflow oven; (2) the calculation of the heat transfer from the PCB to the air as the PCB moves throughout the woven; and (3) use a “dummy” PCB with two generic components with different dimensions and analyze the heat dissipation. The geometry definition, the mesh generation, as well as the numerical simulations were carried out using the Workbench™ platform from ANSYS® 15. It was programmed an UDF to represent the relative motion between the PCB and the cooling air flow. Results shown that, during the cooling process, there is a gradient over the PCB board. It is also observed that there is a small differentiation in the temperatures’ profile along the board length probably because of the formation of recirculation areas inside the oven. Thus, nozzle spacing has a great impact in the formation of those recirculation areas, and consequently in heat dissipation.

Commentary by Dr. Valentin Fuster
2016;():V002T02A025. doi:10.1115/IMECE2016-66514.

One of the crucial elements of image based inspection system development is the lighting conditions. It directly defines the quality of the image which in turn affects the accuracy and robustness of an inspection procedure using machine vision system. The common image characteristics change with variation in lighting leading to large image differences. In recent years, evaluation of surface roughness of a work piece by machine vision has received a great deal of attention. However, practical surface roughness instruments based on machine vision are still difficult to develop for application specific online assessment in particular. This is due to the fact that the images taken from the machined surfaces are affected by illumination, reflectivity and ambience during the image acquisition process. This lighting inhomogeneity is considered to be a disturbing signal component, which should be suppressed to achieve consistency in surface roughness quantification. In this paper, the illumination compensated images are used for surface roughness evaluation. The homomorphic filtering and Discrete Cosine Transform (DCT) based normalization techniques are utilized to remove the illumination inhomogeneity and the performance of these techniques were compared. The results clearly indicate that it is important to consider the lighting conditions when the machine vision approach is used to quantify the surface texture parameters.

Commentary by Dr. Valentin Fuster
2016;():V002T02A026. doi:10.1115/IMECE2016-66551.

The use, and the joining process, of dissimilar materials have recently been highlighted. Joining of dissimilar materials can however be problematic, due to different material properties. Different materials respond differently to temperature changes and this might lead to deformations and stress in the final assembly. The joining methods differ also often from the one used to join similar material.

Variation simulation is used to predict the geometrical variation of a subassembly or a final product. In variation simulation of dissimilar materials it is important to include material properties in order to achieve an accurate result. Also the effects form joining method must be included in the simulation. To join dissimilar materials like plastic and sheet metal parts, clip fasteners are often used.

This paper presents a method for variation simulation of dissimilar materials with a focus on how to model clip fasteners. The method allows effects of temperature changes on holding forces and geometrical variation in the final assembly to be evaluated. Holding force refers to the force a clip fastener must withstand after the parts are joined. The method proposed can be used to support the design and selection of clip fasteners.

Topics: Simulation , Fasteners
Commentary by Dr. Valentin Fuster
2016;():V002T02A027. doi:10.1115/IMECE2016-66618.

Slug rivet is widely used in aircraft assembly due to the higher interference fit level and the longer fatigue life. However, the inhomogeneity of riveting interference value along the thickness direction of the aircraft panels always leads to inevitable deformation, which significantly degrades the dimensional accuracy of the final products. In this study, a quantitative model is established to describe the relationship between several riveting parameters (i.e. squeezing force, buck cavity, upsetting rise time, upsetting dwell time and clamping force between sheets) and the deformation of a formed slug rivet joint. Then the coefficient of variance (CV) is introduced to evaluate the homogeneity of deformation. Subsequently, an optimized combination of the presented parameters is obtained by using finite element method (FEM) simulation so as to generate more uniform deformation. Finally, the FEM model is validated by a series of orthogonal experiments conducted in G86 fully automated C-frame riveting machine and the results show that the squeezing force and the buck cavity are the main significant factors and contributors to the riveted joints deformation, and the sequence of this effect from the high to low are: upsetting dwell time, clamping force, and upsetting rise time. The results also indicate that the developed FE model can be used for further analysis, including the prediction of large component riveting deformation and the mechanical properties of riveted joint.

Commentary by Dr. Valentin Fuster
2016;():V002T02A028. doi:10.1115/IMECE2016-66940.

Cellular metamaterials are of immense interest for many current engineering applications. Tailoring the structural organization of cellular structures leads to new metamaterials with superior properties leading to low weight and very strong/stiff materials. Incorporation of hierarchy to regular cellular structures enhances the properties and introduces novel tailorable metamaterials.

For many complex cellular metamaterials, the only realistic manufacturing process is additive manufacturing (AM). The use of AM to manufacture large structures may lead to several types of defects during the manufacturing process, such as missing/broken cell walls, irregular thickness, flawed joints, missing (partial) layers, and irregular elastic plastic behavior due to toolpath. For large structures, it would be beneficial to understand the effect of defects on the overall performance of the structure to determine if the manufacturing defect(s) are significant enough to abort and restart or whether the material can still be used.

Honeycomb structures are used for the high strength to weight ratio applications. These metamaterials have been studied and several models have been developed based on idealized cell structures to explain their elastic plastic behavior. However, these models do not capture real-world manufacturing defects resulting from AM. The variation of elastic plastic behavior of regular honeycomb structures with defects has been studied, but the performance of hierarchical honeycomb structures with defects is still unknown. In this study, the effects of missing cell walls are investigated to understand the elastic behavior of hierarchical honeycomb structures through simulations using finite element analysis. Regular (zero order), first order and second order hierarchical honeycombs have been investigated in this study. The first level of hierarchy has been implemented by changing each three edge vertex of a regular hexagonal honeycomb lattice by adding another smaller hexagon. The second level of hierarchy is created by adding another smaller hexagon at each three edge vertex of the hexagons added for the first order hierarchy. For the hierarchical cases, the overall density of the honeycomb is held constant to the parent structure (zero order or regular) by reducing the thickness of the cell wall in the first and second order structures. ANSYS® was used to develop finite element models to analyze the performance of both perfect and defected regular, first order and second order hierarchical honeycombs. Defects were added to the model by randomly removing cell walls. Hierarchical honeycombs demonstrated more sensitivity to missing cell walls than regular honeycombs. On average, the elastic modulus decreased by 45% with 5.5% missing cell walls for regular honeycombs, 60% with 4% missing cell walls for first order hierarchical honeycomb and 95% with 4% missing cell walls for second order hierarchical honeycombs.

Commentary by Dr. Valentin Fuster
2016;():V002T02A029. doi:10.1115/IMECE2016-67296.

A fifth order piecewise spline interpolation model has been developed for computing the evolving geometry of a plate deformed by line heating thermal gradients. 3D formulations are presented and applied to continuously derivable geometries to demonstrate the capability of the methodology. Then the developed formulation is used to form gradually, with a sequence of heating lines, a 3D shape from an initially flat plate. The geometric results obtained from finite element simulations with three heating lines are used to illustrate where heating lines should be applied on a flat plate to achieve the intended geometry of a workpiece. Furthermore, it is shown that applying the developed piecewise fifth order spline interpolation model to the same flat plate produces results very close to the ones obtained from the thermal structural FE simulations.

Commentary by Dr. Valentin Fuster
2016;():V002T02A030. doi:10.1115/IMECE2016-67495.

While additive manufacturing allows more complex shapes than conventional manufacturing processes, there is a clear benefit in leveraging both new and old processes in the definition of new parts. For example, one could create complex part shapes where the main “body” is defined by extrusion and machining, while small protruding features are defined by additive manufacturing. This paper looks at how optimization and geometric reasoning can be combined to identify optimal separation planes within a complex three-dimensional shapes. These separations indicate the joining processes in reverse. The optimization method presents possible manufacturing alternatives to an engineering designer where optimality is defined as a minimization of cost. The process identifies the cutting planes as well as the combination of processes required to join the individual parts together. The paper presents several examples of complex shapes and describes how the optimization finds the optimal results.

Commentary by Dr. Valentin Fuster
2016;():V002T02A031. doi:10.1115/IMECE2016-67553.

The jamming of granular materials, which indicates how disordered particle systems change from mechanically unstable to stable states, has attracted significant recent interest due, but not limited, to the appearance of jamming transition or similar behavior in a broad variety of systems. Recent experiments on jamming transition have revealed the relationship between mean coordination number and packing fraction for different jammed states. In this paper the jamming states of two dimensional granular materials under cyclic compression using Smooth Particle Hydrodynamics (SPH) approach is numerically investigated. The SPH method allows one to study the stress developed within individual granular particles of arbitrary shape. In this study the granular system is cyclically and isotropically compressed or expanded. The system undergoes a range of jamming states over a large number of cycles. We measure the evolution of global pressure, mean coordination number, and packing fraction. The force chains and probability density function of force for different compression cycles are also investigated.

Commentary by Dr. Valentin Fuster
2016;():V002T02A032. doi:10.1115/IMECE2016-68142.

Residual stress (RS) pattern of thick T-joint welds, which directly affects fatigue life, varies considerably depending on the thickness and number of passes. Nowadays, most approaches to predict fatigue life do not consider RS real value due to the difficulty of estimating them, hence, they tend to be conservatives. However, recent works have demonstrated that considering RS the conservative error in life prediction can be reduced down to around 15%.

In the present work, the fatigue performance of multipass T-joints of S275JR plates for a thickness range from 20 to 60mm is evaluated considering RS. It is observed that maximum RS value for thick plates decreases progressively (down to 66% of yield stress). Consequently, fatigue performance of different thickness T-joint samples subjected to the same stress load cycles varies considerably in the HCF regime.

Commentary by Dr. Valentin Fuster

Advanced Manufacturing: Innovative Product Design

2016;():V002T02A033. doi:10.1115/IMECE2016-65697.

Complex systems are not of static nature. Most are governed by a particular set of laws and behave accordingly to a certain range of expected inputs and variables, but they can also evolve in response to unforeseen stimulus. The same principle can be applied to industrial information systems. Larger systems such as an entire company or a network of companies may be divided into further subsystems, including information systems, each behaving autonomously but is still under influence of the others, interacting with them in a holistic manner. This paper explores this relationship and proposes a conceptual solution to the strain of sustaining interoperability in complex service-based networks from the domain of manufacturing. To such effect, and in order to tackle the complex relationships and dependencies implicit in web-service environments, information modeling is used, allowing for the optimization of several service engineering activities and enterprise business processes while maximizing the efficiency of system’s interactions. Hence, service modeling and orchestration is here suggested as a baseline to network monitoring, and as a possible approach to automatically handle and recover from erratic behavior, providing systems with adaptive web services and self-organizing capabilities.

Commentary by Dr. Valentin Fuster
2016;():V002T02A034. doi:10.1115/IMECE2016-65704.

Nowadays companies do not thrive solely through their own individual efforts and isolated knowledge. Enterprises have to become agile, sensitive to changes in market forces, and capable of responding with incremental modifications in business and services provided (adaptation) as well as anticipating radical changes by responding with new and breakthrough business models (innovation). This involves a mix of both cooperative and competitive elements, where decision support, evolving information systems, and the use of networking concepts such as the virtual enterprise or the enterprise ecosystem is becoming more common. The approach here presented aims at facilitating and sustaining interoperability in a dynamic networked enterprise environment. Relying on domain-based semantic translation services, sustainable interoperability enables each organization to keep its own terminology and seamlessly communicate with others (i.e. enterprise interoperability). This work contributes to that paradigm, proposing a novel mechanism based in probabilistic analysis (PA), case-based reasoning (CBR) and similarity calculation (SC) to support decision, service redesign and mapping modifications, e.g. when a company changes its internal model but wants to ensure that communication with external entities is not affected.

Topics: Sustainability
Commentary by Dr. Valentin Fuster
2016;():V002T02A035. doi:10.1115/IMECE2016-65964.

Open control architectures have many advantages including increased computational resources and flexibility of reconfiguration of new manufacturing units. This paper proposes an open architecture for the control of CNC systems based on open source electronics. The software architecture in this paper is a component-based approach where each component has an independent finite state machine (FSM) model. The hardware architecture is a multiprocessor distributed controller, with different levels of processing, and adaptable for different hardware specifications. A discussion of the basic control algorithms, with examples of implementation to the open source platform Arduino, is presented as part of the methodology. Other results in this paper include the preliminary test of the control to a two-axis CNC stage and a mathematical model of the control-loop in Simulink. The architecture in this paper has the potential of transforming CNC in open source electronics from device-oriented systems to systems where users can design their controls for special purpose machines.

Commentary by Dr. Valentin Fuster
2016;():V002T02A036. doi:10.1115/IMECE2016-66427.

3D shape recognization technique is rapidly advancing from last decade in the fields of manufacturing, computer science, entertainment and medical technology. Due to the restriction of size and area of cavity, it’s challenging to develop such non-contact optical technologies for scanning. 3D digitization technology plays a vital role in the field of dentistry benefiting dentists and patients by eliminating long time procedures for making the prosthesis/abutments and results into ultimate comfort. In this paper, we have recounted a design of a prototype for a three-dimensional intra-oral scanner using the principle of fringe projection and active triangulation method. LED as a light source passed through the liquid crystal on silicon (LCoS) which radiates the light into three colors and strikes onto the collimating lens assembly and then passed through the optical deflectors. Once the light strikes the object through scanning window it is guided back through the flat reflectors and the fringe pattern on the object is stored into the gray encoding plate. With the help of camera all these images are stored. After the acquisition of images, firstly it will calculate the phase distribution using four-step phase shifting algorithm and unwrap the wrap phase which helps us in getting accurate images. Later, we get display of scanned oral cavity onto the computer screen. Phase-height mapping algorithm has been realized for the reconstruction of the 3D real time reconstruction of the scanned oral cavity which helps us in fast scanning with accurate data. A novel approach of LED as a light source and LCoS display for scattering light fragments into three different colors helps us to scan more effectively for registration of dental surfaces from the patient’s mouth more accurately. Apart from that, its sleek design helps to scan with less pain to the patient’s having low mouth opening. Experiment was performed on the prototype of denture and using this proposed method we have achieved the accuracy of 25μm and it took around 180 sec for the full arc scan of the lower oral cavity. The result of scanned data was checked using the CAD/CAM software for dentistry and compared with the prototype data of denture. Further this image can be used for making prosthesis/abutment directly into production using 3D printing machine or the milling machine. Thus, an abutment or prosthesis obtained with this method is of high quality and eliminates conventional long procedures which helps in reducing pain of patient’s and helps dentists to attain more patients in less time.

Commentary by Dr. Valentin Fuster
2016;():V002T02A037. doi:10.1115/IMECE2016-66516.

The current manufacturing sector has the objective of maximizing profit by minimizing waste, proper utilization of men, machine and materials. Apart from this, the focus has been on implementing green manufacturing practices in operations. The lean -green topic is an emerging and the new one in the present scenario. The main aim of the green practices is to improve operational activities as well as environmental efficiency. Green practices are concerned with the environmental, social and economic impacts over any organization. Lean manufacturing has been coined by nine wastes. These wastes have an impact on green practices, leading to generation of green wastes. Some of the green waste was excessive resource usage, power usage, pollution, improper health and safety. Lean and green are concurrent manufacturing practices focusing on wastes. The present industrial scenario has been looking into implementing these practices in their operations. A few practices relating to lean-green practices, are integration of lean -green concepts, organization performance analysis, functions, assessment performance and empirical study etc. One of the primary activity of lean-green strategies is showing respect to the workforce. Human factor will be considered as one the main pillars in the lean-green practices. In this research paper a model has been proposed for identification of a Lean-Green Resourced Person (LGRP) for integrating and implementing lean and green practices in a manufacturing industry. Identification of LGRP will help the organization in implementing and executing lean-green strategies into their operations. A multicriteria decision making method has been used for finding the LGRP in the industry. The identification will result in reductions in time consumption during implementation, guiding the industry in a proper way for implementing and integrating the lean-green techniques.

Commentary by Dr. Valentin Fuster
2016;():V002T02A038. doi:10.1115/IMECE2016-66897.

Transportation is a sector of activity in permanent change. From airplanes to cars, trains and boats all forms of transportation aim at meeting personal or business needs of displacement of persons and goods. Those needs include safety, reliability, on time with the best effectiveness, and finally, providing the best price. This paper aims at studying car transportation’s consequences regarding last developments that culminate in the self-driving cars. This study analyses the impact of such changes at social and industrial level, considering also the coexistence of traditional cars and self-driving cars in diverse aspects. The authors aim to establish a proficient debate on such important changes for the near future, to create awareness of the potential consequences of such societal and business revolution and generate some conclusions addressing these complex challenges for the years to come. This paper also issues some recommendations for the coexistence of self-driving, autonomous and traditional cars during the transitory period.

Commentary by Dr. Valentin Fuster
2016;():V002T02A039. doi:10.1115/IMECE2016-66917.

Mechanical project is a task that requires knowledge about materials and technologies. The need for those skills is supported by mathematical knowledge associated with such technologies. Disabled people can have tremendous skills in terms of calculation and conception of mechanical devices but they may lack on proper access to handle tools that represent parts or mechanisms in terms of graphical design. The present research aims at deploying a setup that can help on such task by allowing drafting in AutoCAD using the eyes. The proposed approach makes use of a laptop camera to act as an eye-tracker, thus avoiding additional hardware costs. The authors envisage new opportunities from this work to future work, including the possibility of disabled people to build 3D real models from the generation of STL models to export to 3D printing devices.

Commentary by Dr. Valentin Fuster
2016;():V002T02A040. doi:10.1115/IMECE2016-66941.

Nowadays, and due to the shortage of wild fish in our seas, rivers and lakes has led to the growth of the aquaculture industry and consequently to the increase of existing aquaculture fish in the markets for domestic consumption to a global scale. In this sense, aquaculture plays a central role to feed the world population in a healthy way and simultaneously for the preservation of the aquatic ecosystems. Thus, the aquaculture production process can be determined by several factors namely biological, technological, economic, and environmental. The authors intend to address and validate such factors related to production processes in the AquaSmart project using serious games. The Serious Games strategy proposes to demonstrate the technological results of the project, namely data analytics tools able to generate new knowledge to improve aquaculture production processes. Additionally, it also intends to work as supporting training and marketing material, validating both the tools and the training programme.

Topics: Manufacturing
Commentary by Dr. Valentin Fuster
2016;():V002T02A041. doi:10.1115/IMECE2016-66992.

A shipboard piping system can be considered analogous to the transport and distribution system of a land-based piping system. The intakes and supply pumps provide the initial uptake and head pressure while the piping system provides the distribution throughout the rest of the ship. Piping systems must not degrade or corrode due to the contained fluid but also must endure structural loadings. Interior damage can come in the form of corrosion such as pitting, general wasting away of material due to galvanic corrosion, mechanical deformations due to structural and vibrational loadings. A decision matrix based framework for evaluation using a modified Pugh Controlled Convergence technique was developed for evaluation of metallic coatings under consideration for shipboard system repairs which included mechanical and electrochemical performance characteristics. Candidate coatings for further study and additional testing requirements are identified through the process. The mechanical evaluation focuses on microstructural characterization and mechanical response. The electrochemical evaluation focuses on general corrosion and galvanic interactions between each coating and Cu0.7Ni0.3, a common piping material also often referred to as 70-30 CuNi. The outcome of the evaluation sequence is the ranking of relative merit of coatings. Results are presented which show the wide range of characteristics possible. The extension of the decision matrix to manufacturability issues will also be discussed.

Commentary by Dr. Valentin Fuster
2016;():V002T02A042. doi:10.1115/IMECE2016-67002.

The growth of the elderly population enhances the importance of the quality of the healthcare, which should be administered daily by professionals, whether on a temporary or permanent basis. A core issue to take into account, in this context, is the characterization of these services, especially their adaptation to the specific needs of the bedridden people. In doing so, the quality of life of caregivers, in what concerns facilitating their daily tasks, is also taken into account. A questionnaire was developed to gather information allowing the characterization of both needs and gaps in healthcare identifying the particularities and necessities of the provided services. The questionnaire focuses on three targets: the bedridden characterization, the permanent caregiver and the non-permanent caregiver. The study is descriptive and exploratory, contemplating a quantitative approach. The main objective of the study is to define the important areas worthy of attention, to protect the healthcare of caregivers in the utilization of devices and to be able to build products without structural problems, thus, creating better condition of life and offer solutions in some contexts and tasks, such as, comfort, hygiene and safety.

Commentary by Dr. Valentin Fuster
2016;():V002T02A043. doi:10.1115/IMECE2016-67154.

This paper focuses on the redesign of an innovative punch and bind machine. Business machines can be integrated with recent technology that enables productivity and efficiency. Integrating smart technologies in the existing traditional business machines will ease the evolution of these systems. The creation of a pilot platform is required, which enables further developments on servitization. In order to ease and increase the office document binding rate, as well as reduce the probability of errors to occur, efforts were made to develop a measuring system which allows the correct measurement of the document and simultaneously specify the appropriate binding spine. Developments were made in a system that allows the inserted spine verification. In addition, a system for automated document binding, with the correct position of paper sheets was developed. The integrated platform allowing communication between all systems is presented. The new system has several advantages in both its hardware design and its underlying sensors, providing a significant improvement in performance and upgradability over existing systems. The mechatronic system combines mechanical position sensing with electronics implementation of the hardware and the basic algorithms. This solution consists in a system that allows the punch and bind optimization of a range of sheets of paper, plastic or other materials.

Topics: Machinery
Commentary by Dr. Valentin Fuster
2016;():V002T02A044. doi:10.1115/IMECE2016-67316.

Aquaculture is probably the fastest growing food-producing sector in the world producing nearly 50 percent of the fish that is used for food, according to the Food and Agriculture Organization of the United Nations (FAO). With the growing of the Aquaculture sector, problems of global knowledge access, seamless data exchanges and lack of data reuse between aquaculture companies and its related stakeholders become more evident.

From an IT perspective, aquaculture is characterized by high volumes of heterogeneous data, and lack of interoperability intra and inter-organizations. Each organization uses different data representations, using its native languages and legacy classification systems to manage and organize information, leading to a problem of integrating information from different sources due to lack of semantic interoperability that exists among knowledge organization tools used in different information systems.

The lack of semantic interoperability that exists can be minimized, if innovative semantic techniques for representing, indexing and searching sources of non-structured information are applied. To address these issues, authors are developing a platform specifically designed for the aquaculture sector, which will allow even small companies to explore their data and extract knowledge, to improve in terms of use of feed, environmental impact, growth of the fish, cost, etc.

Commentary by Dr. Valentin Fuster

Advanced Manufacturing: Manufacturing and Assembly of Two-Dimensional Materials and Composites

2016;():V002T02A045. doi:10.1115/IMECE2016-66270.

This paper mainly discusses the effect of coupling on the tensile properties of glass fiber (GF)/carbon fiber (CF) reinforced polypropylene (PP) hybrid composites which were made through a new injection molding process named direct fiber feeding injection (DFFIM) process. It is mainly divided into two parts which discusses the functional of coupling agent in the composites system, and the different contents of coupling agent (PA6 and MAPP) on the tensile properties of composites. DFFIM progress is a new method that by directly feeding of continuous carbon fiber into the barrel of injection molding machine to make the hybrid composites. The continuous CF roving strands are guided into the vent of devolatilizing unit of injection barrel and fed into the melt by the shearing motion of the screw during plasticization process. By using DFFIM process to make composites, the fiber attrition during extrusion compounding will be eliminated. It is a great improvement in reduction of material cost. And also the cost of reinforcing compounded pellet in the traditional composites market value chain could be lower. Polyamide 6 (PA6), Maleic anhydride-grafted polypropylene (MAPP) or both of them were mixed with pellets during the DFFIM process and PA6 and MAPP were used as coupling agent for CF/GF reinforced PP system. The CF and GF contents in each hybrid composites were tested to analysis the influence of fiber contains on the tensile properties of composites. Usually, better interfacial bonding between fiber and matrix in composites, better tensile properties of composites. So the effect of coupling agent (PA6 and MAPP) on the interfacial bonding between CF and PP in hybrid composites were firstly analyzed. And then the influence different contents of PA6 and MAPP on the tensile properties of GF/PP composites and GF/CF reinforced PP hybrid composites were investigated. It is found that the addition of PA6 did not improve the interfacial bonding but the addition of MAPP has shown a little improvement to the bonding between CF and PP. And when using PA6 and MAPP together as co-coupling agent, the tensile properties of composites has greatly increased. And, there is fiber aggregation in the core layer of the hybrid composites which made by DFFIM process, while there is no such phenomenon happened in the condition of normal injection molding process. It is the main reason that the tensile strength of hybrid composites without coupling agent is weaker than the GF/PP composites. And the tensile modulus of composites would be increased considerably. That is due to the addition of the carbon fiber which has high tensile modulus. In the condition of composites with 1wt.% PA6, the 1wt.% PA6 shows positives effect on tensile properties and while PA6 has negative role when the amount of PA6 has improved. Within a certain range, the larger amount of MAPP in the system of MAPP-PA6 composites, the better on the tensile properties of composites is. And MAPP has positive effect on the tensile properties of composites.

Commentary by Dr. Valentin Fuster

Advanced Manufacturing: Nanomanufacturing: Novel Processes, Applications, and Process-Property Relationships

2016;():V002T02A046. doi:10.1115/IMECE2016-67226.

Hierarchical, branched carbon nanotube (CNT) forest assemblies were created by synthesizing a second generation of CNTs directly from the alumina-coated surface of a parent CNT forest. First, a parent CNT forest generation was synthesized using floating catalyst chemical vapor deposition (CVD) in which gaseous argon and hydrogen are flowed into a tube furnace, along with a controlled flow rate of ferrocene nanoparticles suspended in xylene solvent. Next, a thin alumina coating was applied to the parent CNT forest using atomic layer deposition (ALD). The ALD process pulses alternating gases of water vapor and trimethylaluminum (TMA) and is repeated for 100 cycles, yielding a 10nm coating. This coating adheres to the outer walls of the larger CNTs and serves as a supportive surface to enable the growth of a second CNT generation. Finally, a second CNT generation was synthesized from the parent CNT forest using a floating-catalyst CVD method similar to that used for the parent generation. The relatively low areal density of the parent CNT generation allows for gas-phase additive processing (i.e. ALD and floating catalyst CVD) to occur deep within the volume of the original parent CNT forest.

Transmission electron microscopy analysis of the hierarchical CNT forests shows that second-generation CNTs nucleate and grow from the alumina-coated walls of the parent generation rather than nucleating from the original growth substrate, as has been previously reported. Further, physical confinement of the second-generation catalyst particle on the external surface of the parent generation CNTs (28 nm average diameter) leads to small-diameter CNTs (8 nm average) for the second generation. Further, radial breathing modes are detected by Raman spectroscopy, indicating single-walled or few-walled CNTs are synthesized in the second generation.

The hierarchical forests exhibit many desirable properties compared to single generation forests. Because the second generation CNTs within the interstitial regions of the parent CNT forest, they increase the structural rigidity of the cellular CNT forest morphology, increasing in mechanical stiffness by ten-fold, relative to the parent CNT forest. Further, we demonstrate that electrical continuity between the CNT generations is retained. Because a thin alumina buffer layer exists between CNT generations, electrical continuity is not guaranteed. Cyclic voltammetry and electrochemical impedance spectroscopy are used to characterize the electrical resistance elements within the hierarchical forest. This hierarchical structure offers a new avenue to tailor the performance of CNT forests and offers performance enhancements for applications in thermal interfaces, electrical interconnects, dry adhesives and energy generation and storage.

Commentary by Dr. Valentin Fuster
2016;():V002T02A047. doi:10.1115/IMECE2016-67312.

Laser assisted additive manufacturing (LAAM) is regarded as a complementary manufacturing method to traditional manufacturing technologies. Meantime, improving the mechanical performance of components fabricated by LAAM is an important research focus in recent years and it has drawn significant attention from both industrial and research aspects. In the present study, in order to obtain high-performance metal components by LAAM, nano-TiC particles are used to reinforce Inconel 718 and the mixed raw powder is processed by selective laser melting (SLM) technique. To investigate the effect of TiC amount on the property and performance of the composite, samples with four levels of nano-TiC addition (0, 0.4, 0.8 and 1.6 wt.%) are prepared, all other manufacturing parameters are set fixed. Furthermore, standard solid solution treatment at 980 °C for 1 hour is carried out to investigate its effect on the final properties. SEM observations are performed to analyze the microstructure of the composites. In addition, to understand the reinforcing mechanism of nano particles in LAAM-produced metal composites at both as-built and heat treated state, we consider four main strengthening mechanisms, (a) load-bearing effect, (b) enhanced dislocation density due to the residual plastic strain caused by the difference in the coefficients of thermal expansion (CTE) between the matrix and reinforcing particles, (c) Orowan strengthening effect, and (d) Hall-Petch strengthening. The effect of TiC nano particle amount on each of the four strengthening mechanisms is investigated separately and the results show that within the investigated range, the increase of reinforcement content leads to higher tensile strength. With 1.6 wt.% reinforcement, the ultimate tensile strength increases by 15%. At as-built condition, the composites have the maximum yield strength (YS) and ultimate tensile strength (UTS), while for solution treated samples, the tensile strengths are overall lower due to microstructure coarsening. Through quantitative investigation, it is found that both as-built and solution treated conditions, the load-effect strengthening effect is very small as compared with other contributors. Thermal mismatch strengthening effect is most significant at any volume fraction under as-built condition, mainly due to high SLM temperature. However, for solution-treated condition, CTE mismatch strengthening is weakened because solution treatment significantly equilibrates the thermal strain in the composite, and diminishes most strain-induced dislocations. However, Hall-Petch strengthening becomes dominating as large amount of nanoparticles effectively inhibit the grain coarsening during solution treatment.

Commentary by Dr. Valentin Fuster

Advanced Manufacturing: Sensing, Measurement, and Process Control

2016;():V002T02A048. doi:10.1115/IMECE2016-65454.

Current diesel engine after-treatment systems such as Selective Catalyst Reduction (SCR) use ammonia (NH3) to reduce Nitrogen Oxides (NOx) into Nitrogen (N2) and water. However, if the reaction between NH3 and NOx is unbalanced, it can lead either to NH3 or NOx being released into the environment. As NH3 is classified as a hazardous compound on the environment, its accurate measurement is essential.

Fourier Transform Infrared (FTIR) and Tuneable Diode Laser (TDL) spectroscopy are two of the methods that can measure raw emissions from engine exhaust pipes, especially NH3. However, it is difficult to suggest which method is the right one for measuring NH3 from engine exhausts.

This paper compares the effectiveness of FTIR and TDL methods for NH3 measurement from diesel engine exhausts, based on tests conducted under well-controlled laboratory conditions. The concentration of NH3 from a diesel engine was measured under both a steady-state test cycle and a transient test cycle. The NH3 readings from FTIR and TDL were analysed, for comparison of precision, response time and their accuracy. It was shown that both techniques were suitable with attention to the different sampling procedures to avoid absorption.

Commentary by Dr. Valentin Fuster
2016;():V002T02A049. doi:10.1115/IMECE2016-65748.

Tool failure remains one of the most challenging phenomena in machining that affects the productivity and product quality, and hence the cost. In high feed rough milling operations of hard-to-cut materials, chipping and breakage have been observed as the dominant failure modes of the end mill cutters. Most of the work in the open literature is focusing on either detecting the complete tool breakage after it takes place or detecting the progressive tool wear. Detecting the abrupt/sudden tool failure due to tool chipping before it takes place, which is essential to avoid any damage to the machined part, has not been addressed. Therefore, the main objective of this research work is to investigate the ability of using the process monitoring signals in order to detect the tool pre-failure and failure by chipping/breakage in intermittent cutting operations. A method was devised to induce impact load on the cutting tool tip to study the features of signals collected by various sensors due to unstable crack propagation and chipping, while ensuring minimal tool wear effect. The acoustic emission (AE) signal features were able to successfully capture tool pre-failure, while other signals could detect the failure occurrence only.

Topics: Cutting , Failure
Commentary by Dr. Valentin Fuster
2016;():V002T02A050. doi:10.1115/IMECE2016-65948.

A multi-wavelength light interference method for the measurement of lubricating film thickness was proposed for the improvement of convenience and accuracy of monochromatic light interferometry. Through the successive analysis of the hypothetical curves and the revised curves of three-wavelength light interference, the procedures of this method were discussed in detail. Then three-wavelength light interference method was applied to measure the lubricating film thickness of base oil under a specific condition. In comparison with the numerical results of Hamrock-Dowson formula, it was concluded that the multi-wavelength light interference method is applicable for the measurement of lubricating film thickness. With this method, the only requirement is the images which captured in stationary and purposed conditions, and higher measurement accuracy can be achieved.

Commentary by Dr. Valentin Fuster
2016;():V002T02A051. doi:10.1115/IMECE2016-67952.

The cutting ability of abrasive grains is considerably changed by wheel loading and leads to excessive rubbing at the wheel-work interface. Therefore, the wheel life, the overall performance of the grinding operation and the surface finish of the work piece are directly having an effect by the amount of loading over the wheel periphery. Wheel loading can, thus, be considered as an important factor for evaluating the grinding process. Though, few monitoring systems based on ultra sound and acoustic emissions are on the research anvil, they demand high investment. Monitoring of grinding wheel loading, using IR (Infra Red) which is affordable and cost effective for small scale industries is the scope of the present work. This work involves study on the temperature on cutting surface of grinding wheel during machining process. This information helps to understand the influence of temperature on wheel loading. In this respect, the experiments were carried out with Aluminium Oxide (Al2O3) and Silicon Carbide (SiC) grinding wheels over High carbon High chromium steel (HCHCr) and Mild steel specimens. The grinding wheels and specimens were chosen for pilot study, as they are widely used in Indian small scale Industries. The experiments were carried out with (WC) and without (WOC) general purpose soluble oil coolant. Temperature measurements were recorded at two locations on the grinding wheel to understand the distribution. The results show that the temperature rise during grinding was insignificant to cause any influence on the wheel loading.

Commentary by Dr. Valentin Fuster

Advanced Manufacturing: Sheet Metal and Tube Forming: Novel and Hybrid Processes, Material Characterization, and Control

2016;():V002T02A052. doi:10.1115/IMECE2016-65262.

The bending of complex curved sheet metals of ship hull has long been a challenge in shipbuilding yard on account of some inherent defects of the traditional forming processes such as the line heating. This paper presents a novel incremental bending process based on punching to obtain complex curved steel plates in order to take the place of those inefficient traditional forming processes of ship hull.

The presented incremental bending process is carried out by a series of stepping punches, so it is also defined as incremental punching in this work. By means of this process, the blank plate that is fixed and held by a flexible supporting system can incrementally be bent to the target shape by a press tool with a planned tool trajectory one step after another. Meanwhile, in order to improve geometric accuracy of the formed work-piece, a 3D scanning feedback system is applied to measure the deformation of the work-piece during the forming process. Three dimensional shape of the formed work-piece can be imaged and rebuilt with a large amount of point cloud data by the 3D scanning feedback system. Then the difference between the rebuilt model of the formed work-piece and the target CAD-model can be acquired, which can be used for feedback control of the forming accuracy if necessary.

To validate the presented forming process, an original incremental punching prototype was designed and manufactured, which is mainly composed of a 3-axis CNC machine, a flexible supporting system and a 3D scanning feedback system. A forming experiment of a gradual curvature steel plate was carried out using this prototype and is discussed in detail in this paper in order to demonstrate the feasibility of the proposed incremental bending process of complex curved steel plate.

Topics: Sheet metal
Commentary by Dr. Valentin Fuster
2016;():V002T02A053. doi:10.1115/IMECE2016-65621.

Lightweight design for automotive applications gains more and more importance for future products, independent from the powertrain concept. One of the key issues in lightweight design is to utilize the right material for the right application using the right value at the right place. This results irrevocably in a multi-material design.

In order to increase the efficiency in manufacturing car components, the number of single parts in a component is decreased by increasing the complexity. Examples for the state of the art are tailored welded blanks in cold forming, tailored tempering in press hardening or metallic inlays in injection molding of polymers.

The challenge for future production scenarios of multi-material components is to combine existing technologies for metal- and polymer-based applications in efficient hybrid process chains.

This paper shows initial approaches of hybrid process chains for efficient manufacturing of hybrid metal-polymer components. These concepts are feasible for flat as well as for tubular applications. Beside the creation of the final geometric properties of the component by a forming process, integrated joining operations are increasingly required for the efficiency of the production process and the performance characteristics of the final component. Main target of this production philosophy is to create 100% ready-to-install components. This is shown in three examples for hybrid process combinations.

The first example deals with the combination of metal forming and injection molding of polymers. Example number two is the application of hybrid metal-polymer blanks. Finally, example number three shows the advantages of process integrated forming and joining of single basic components.

Commentary by Dr. Valentin Fuster
2016;():V002T02A054. doi:10.1115/IMECE2016-65783.

Force-based closed-loop control of stamp forming processes have in the past been investigated in order to improve the formability of sheet metal when forming automotive body panels. Previous researchers have controlled local forces and wrinkling using active draw beads and variable blank holder forces. However, it has been recognized that strain-based control in critical locations may be more effective. This study is an initial examination of strain-based control. In order to simplify the problem of strain control, cup forming was utilized and a quasi-automatic proportional control system was utilized. Both finite element analysis and experimental results were examined. It was demonstrated that control at the punch nose resulted in better strain control than at the die shoulder. For this study, two approaches were considered for control. For the first approach, if the effective strains were within +/−0.005 of the target strain, the process was said to be in control while the second approach used a factor of 10% deviation from the target strain to be in control. It was shown that the second method resulted in improved control. However, a third approach, which was a synthesis of the first two approaches resulted in very close agreement between the target strains and the strains from the controlled simulations.

Commentary by Dr. Valentin Fuster
2016;():V002T02A055. doi:10.1115/IMECE2016-65979.

In this work, investigation into a two-stage hybrid and integrated incremental sheet metal processing of EDD sheet has been carried out. EDD steel was chosen for its excellent formability. The hybrid process consists of two stages, the first stage is the conventional spinning process and the second stage is the asymmetric incremental sheet metal forming (AISF) process. The objectives of the proposed hybrid process are reduction of manufacturing time and improved surface finish, in comparison to AISF process alone. In the proposed hybrid process, the geometry of sheet metal part was sub-divided into two groups of features. The first group of axisymmetric features was obtained by spinning process, on top of which, in the second stage, the second group of asymmetric features was superimposed by AISF process. The hybrid process for studying the manufacturing time consisted of negative AISF in the second stage. A substantial overall reduction in manufacturing time was observed. The hybrid process for studying improved surface finish consisted of, on the other hand, positive AISF in the second stage, in which the experiments were carried out using four different lubricants, namely plain canola oil and three different additives in canola oil, namely, molybdenum disulphide, boric acid and maleic anhydride. The surface topography of the sheet in the two stages of hybrid process was determined using a profilometer. It is found that canola oil with molybdenum disulphide gives the best surface quality.

Commentary by Dr. Valentin Fuster
2016;():V002T02A056. doi:10.1115/IMECE2016-67117.

One metal manufacturing process which uses thousands of processes to trim, stretch, draw, bend etc. under a big umbrella is sheet metal forming. Using heavy equipment, the sheet metal parts are deformed into complex geometries. The complexity in these parts produces multi-axial stress and strain, a state for which it is critical to analyze using conventional tools. Traditionally, the mechanical properties of materials have been characterized using the uniaxial tension test. This test is considered adequate for simple forming operations where single axis loading is dominant. Previous studies, however, have noted that the data acquired from this type of testing is not enough and additional details in other axes under simultaneous deformation conditions are important. To analyze the biaxial strain, some studies have suggested using the limiting dome height test and bulge test. However, these tests limit the extent of using multi-axial loading and the resulting stress pattern due to contact surfaces. Therefore, researchers devised the biaxial machine which is designed specifically to provide biaxial stress components using multiple and varying loading conditions.

The idea of this work is to evaluate the relationship between the dome test data and the biaxial test data. For this comparison, cruciform specimens with a diamond shaped thinner gage in the center were deformed with biaxial stretching on the biaxial testing machine. In addition, the cruciform specimens were bi-axially stretched with a hemispherical punch in a conventional die-punch setting. Furthermore, in each case, the process was simulated using a 3D model generated on ABAQUS. These models were then compared with the experimental results. The forces on each arm, strain path, forming and formability was analyzed. The differences between the processes were detailed. It was found that biaxial tests eliminated the pressurization effect which could be found in hemispherical dome tests.

Commentary by Dr. Valentin Fuster
2016;():V002T02A057. doi:10.1115/IMECE2016-67273.

The deep drawing process has been widely used in the industry because it eliminates costly operations such as welding and machining. However, there are many parameters involved that affect the quality of the final products. One of the main parameters of the deep drawing process is the maximum deep drawing force (DDF) or drawing load, which is the maximum force required to perform a particular deep drawing operation. This maximum DDF is needed to define the required capacity of the press, and to calculate the deep drawing work and the process efficiency. Several analytical expressions to estimate the maximum DDF have been proposed in the literature, particularly for cylindrical parts. However, few research works have focused on analyzing the prediction performance of these expressions.

In this paper, the performance of different analytical expressions to estimate the maximum DDF of cylindrical and rectangular parts, is evaluated and compared. Initially, several expressions proposed by different researches for the maximum DDF of cylindrical parts are presented. Then, these expressions are transformed into new expressions for the maximum DDF of rectangular parts by using different concepts of equivalency, such as the equivalent diameter concept. Finally, the prediction performance of all the expressions for both cylindrical and rectangular deep drawing is analysed and compared using experimental data from the literature. The performance is evaluated in terms of the prediction error. The results have suggested that the analytical expressions involving the largest number of parameters have a superior prediction performance than the analytical expressions involving less parameters.

Topics: Machining , Welding , Stress , Errors
Commentary by Dr. Valentin Fuster
2016;():V002T02A058. doi:10.1115/IMECE2016-67324.

There are challenges in the conventional sheet metal folding for mass production; those are summarized by high tooling and energy costs and lack of dimensional accuracy. High cost per product is due to the need of specific manufacturing tools and equipment like dies and molds that are shape dedicated to certain product range and specifications. Lack of high accuracy is resulted from involved forming process, machine structure and springback effects in workpiece.

Origami-based Sheet Metal (OSM) folding fabrication process has been utilized to overcome these challenges. This novel approach is an extension of the origami technique to sheet metal folding process and it requires creating numerous features along the bend line, called Material Discontinuities (MD). MD are fabricated by removal of material completely or partially through thickness direction of sheet metal along the bend line using laser cutting process or progressive stamping. MD can also be created by stamping where no material removal is present, rather stamping creates deformed pattern along the bend line to guide the folding. MD controls the material deformation during bending and results in reduced bending force, minimal tooling and machinery requirements. Despite the promising potential of OSM, there is little understating of the effect of the selected MD shape and geometry on the final workpiece, specifically this is of interest when comparing the energy and cost allocations for OSM with a well-establish process for sheet metal such as stamping.

In this work, the effect of several types of MD on sheet metal folding process is investigated using Finite Element Analysis (FEA). In particular, wiping die bending of aluminum sheet with different MD shapes and geometries along the bend line is compared to the traditional sheet bending of final part in terms of stress distribution along the bending line and required bending force. FE simulations are carried out using structural and thermo-mechanical FE solver Code_Aster. Aluminum 2036-T4 is chosen as sheet metal material. Constitutive model in the simulation is J2 flow theory plasticity with isotropic hardening. The FEA results are validated by comparing it to the available empirical models in terms of bending forces.

This study finds that the OSM technique reduced the required bending force significantly, which has important significance in energy and cost reduction. It also ranked the MD in terms of the required force to bend the same sheet metal type and thickness for further future investigation. However, the MD leads to localized high stress regions along the bending line, which may affect load-bearing capability of the final part. In addition, it may lead to cracks or fractures of sheet metal part in the high stress region, especially if MD are densely arranged along the bend line.

Commentary by Dr. Valentin Fuster

Advanced Manufacturing: Symposium on Additive Manufacturing

2016;():V002T02A059. doi:10.1115/IMECE2016-65067.

3D printing known as additive manufacturing has been widely used in academics and industries to make various 3D objects for various applications. The strength of the 3D printing parts is different from its original material strength due to this additive manufacturing technique. The 3D printing parts should be treated as anisotropic materials. However, the information of mechanical property such as the ultimate strength of 3D printing parts is very limited. There is little information about the mechanical property of 3D printing parts at different print angles. This research was focused on exploring the mechanical properties of 3D printing objects. The tensile test specimen of two different materials: acrylonitrile butadiene styrene-electrostatic dissipative (ABS-ESD) and Nylon 12 were printed at the 5 different print angles through the Fortus 450mc 3D printer. Tensile test results, data analysis, detailed discussion and the empirical formula of the tensile strength of 3D printing objects vs different print angles will be presented.

Commentary by Dr. Valentin Fuster
2016;():V002T02A060. doi:10.1115/IMECE2016-65330.

Fused Deposition Modeling (FDM) is a popular style of additive manufacturing (AM) where a 3D object is fabricated by a molten material deposited into successive 2D layers. Multi-material 3D printing is particularly challenging due to poor adhesion between dissimilar plastics. The majority of currently available multi-material printers use separate nozzles for each material. Therefore, they are incapable of producing devices made of functionally gradient materials (FGM). FGM is a special class of engineering material exhibiting spatially inhomogeneous content, which tailors the material for specific functional and performance requirements. In this work, we present the design and characterization of a bi-material co-extruder system. This specialized extruder is capable of printing two thermoplastic materials through a single nozzle and is also capable of altering the composition of the deposited material while printing. It is also exceptional in that the internal structure of the hot end can be easily accessed and is a more adaptable design than previously reported co-extruders. The extruder was installed on a Geeetech PI3 Pro C printer. Then, some simple structures were printed using pairs of materials including polylactic acid (PLA), acrylonitrile butadiene styrene (ABS) and high impact polystyrene (HIPS). Without any internal mixing features, the composition of the output (for instance, different colored PLA) was determined from microscopic images of cross-section of the extrudates.

Topics: Design , Modeling
Commentary by Dr. Valentin Fuster
2016;():V002T02A061. doi:10.1115/IMECE2016-65907.

In the rapidly growing field of additive manufacturing (AM), the focus in recent years has shifted from prototyping to manufacturing fully functional, ultralight, ultrastiff end-use parts. This research investigates the mechanical behavior of octahedral, octet, vertex centroid, dode, diamond, rhombi octahedron, rhombic dodecahedron and solid lattice structured polyacrylate fabricated using Continuous Liquid Interface Production (CLIP) technology based on 3D printing and additive manufacturing processes. The compressive stress-strain behavior of the lattice structures observed is typical of cellular structures which include a region of nominally elastic response, yielding, plastic strain hardening to a peak in strength, followed by a drop in flow stress to a plateau region and finally rapid hardening associated with contact of the deformed struts with each other as part of densification. It was found that the elastic modulus and strength of the various lattice structured materials are proportional to each other. In addition, it was found that the octahedral, octet and diamond lattice structures are amongst the most efficient based on the measured specific stiffness and specific strength.

Commentary by Dr. Valentin Fuster
2016;():V002T02A062. doi:10.1115/IMECE2016-65910.

Utilizing the advantages of additive manufacturing methods, redesigning, building and testing of an existing integral Savonius / Darrieus “Lenz2 Wing” style vertical axis wind turbine is predicted to improve power generation efficiency. The current wind turbine blades and supports made from aluminum plate and sheet are limiting the power generation due to the overall weight. The new design is predicted to increase power generation when compared to the current design due to the lightweight spiral Darrieus shaped hollow blade made possible by 3D printing, along with an internal Savonius blade made from aluminum sheet and traditional manufacturing techniques. The design constraints include 3D printing the turbine blades in a 0.4 × 0.4 × 0.3 m work envelope while using a Stratasys Fortus 400mc and thus the wind turbine blades are split into multiple parts with dovetail joint features, when bonded together result in a 1.2 m tall working prototype. Appropriate allowance in the mating dovetail joints are considered to facilitate the fit and bonding, as well as angle, size and placement of the dovetail to maximize strength. The spiral shape and Darrieus style cross section of the blade that provides the required lift enabling it to rotate from the static condition are oriented laterally for 3D printing to maximize strength. The bonding of the dovetail joints is carried out effectively using an acetone solution dip. The auxiliary components of the wind turbine which include the center support pole, top and bottom support, and center Savonius blades are manufactured using lightweight aluminum. Design features are included in the 3D printed blade parts so that they can be assembled with the aluminum parts in bolted connections. Analysis of the 3D CAD models show that the hybrid aluminum and hollow 3D printed blade construction provides a 50% cost savings over a 3D printed fully solid blade design while minimizing weight and maximizing the strength where necessary. Analysis of the redesign includes a detailed weight comparison, structural strength and the cost of production. Results include linear static finite element analysis for the strength in dovetail joint bonding and the aluminum to 3D printed connections. Additional data reported are the time frame for the design and manufacturing of the system, budget, and an operational analysis of the wind turbine with concern for safety. Results are analyzed to determine the advantages in utilizing a hybrid additive manufacturing and aluminum construction for producing a more efficient vertical axis wind turbine. Techniques used in the production of this type of wind turbine blade are planned to be utilized in similar applications such as a lightweight hovercraft propeller blade design to be tested in future research projects.

Commentary by Dr. Valentin Fuster
2016;():V002T02A063. doi:10.1115/IMECE2016-65927.

Due to the superior mechanical properties of metals and the inherent capability of additive manufacturing (AM) to fabricate complex structures, metal AM reveals a promising future in the industrial fields. Compared with other metal AM processes, Binder Jetting (BJ) process has potential of producing overhang structures without additional supports. This advantage of BJ process significantly enlarges the design freedom of complex metal parts with intricate overhang structures. However, it should be noted that there is still a certain manufacturing limitation of overhang structures for BJ process. Without the support of loose powder after the depowdering process, the green part is vulnerable to the inevitable external loads, such as self-weight. In this paper, a theoretical model has been proposed to evaluate the self-support capability of printed green parts after the depowdering process. A set of experiments has been designed to find the maximum normal stress that printed green parts can withstand. This proposed theoretical model can be used to predict manufacturability of overhang structure of any arbitrary shape. Based on this model, some design guidelines and future work are summarized at the end of this paper.

Commentary by Dr. Valentin Fuster
2016;():V002T02A064. doi:10.1115/IMECE2016-66186.

Currently additive manufacturing techniques offer great detail in small, difficult to produce parts. They are also relatively slow, limited in scale and very expensive (especially so in the additive manufacturing of metals realm). Wire and arc additive manufacturing enables manufacturers to build parts by depositing metal in layers using welding techniques. The extremely inexpensive Wire 3D (Wir3D) printing process, in development by the authors, uses an electric arc to melt metals at higher deposition rates than other additive techniques in metals. Large parts can be created quicker with less material waste or total machining time than subtractive manufacturing. Unique metal alloys can also be quickly and economically produced without worry of tool wear and the other drawbacks that are related to super alloy manufacturing as with subtractive techniques. A Wir3D additive machine was designed, constructed and evaluated at Auburn University. The wire deposition machine features a modular, open frame design allowing for easy access and continuous upgrades. The machine, which is based upon gas metal arc welding (GMAW) technology, is extremely rapid compared to other additive processes currently available at producing metal objects. Although it cannot currently compete with laser or electron beam additive methods in terms of resolution, these methods will never be able to compete with Wir3D in terms of speed for bulky print jobs, or especially material costs. During the literature review of this emerging technology, it became apparent that a standard reporting format would greatly increase future developments in the field by all researchers. A standard parametric data sheet was developed to establish a common data set for future researchers (included at end) during the experiments’ execution incorporating all of the parameters reported variously in the scattered literature. The printer described in this paper constructed for very little money by students working together. In the development, voltage and current requirements for different wire diameters were analyzed along with resulting wall widths and heights. The tensile strengths of deposited steel structures were measured in multiple orientations achieving up to 90% of standard material values in one orientation. Deposited steel structures were found to be heat treatable. With improved controls and in-process feedback, one-off castings can be easily replaced using this process in a wide array of metals. The wire 3D printing process is a viable option for low cost and rapid manufacturing of metallic objects [1].

Topics: Wire , Printing
Commentary by Dr. Valentin Fuster
2016;():V002T02A065. doi:10.1115/IMECE2016-66245.

Selective Laser Melting (SLM) is one of the important Additive Manufacturing techniques for building functional products. Nevertheless, the absence of accurate models for predicting the SLM process behavior, delays development of cost effective and defects free process. This work presents a coupled thermo-mechanical numerical model to capture the two phase (solid-liquid) solidification melting phenomena that occur in the process. The proposed model will also predict the evolvement of process-induced properties and defects particularly residual stresses caused by temperature gradient and thermal stresses. CO2 or Nd:YAG laser beam can be used as a heat source with a Gaussian distribution for the laser beam energy.

Commentary by Dr. Valentin Fuster
2016;():V002T02A066. doi:10.1115/IMECE2016-66697.

Additively manufactured components enable complex structures to be rapidly fabricated and tested for use in the automotive and aerospace industries. Additive manufacturing capabilities have expanded to include a variety of plastics, metal alloys, and fiber-reinforced polymers. There is interest in quantifying the residual stresses in components that have been manufactured using 3D printing processes in order to refine fabrication parameters and improve the performance of component design. Luna Innovations has developed and demonstrated methods to embed high definition fiber optic sensing (HD-FOS) technology into components that have been additively manufactured using ABS plastic as well as a cobalt chrome alloy. This technology enables characterization of internal residual stresses and provides a method for lifetime health monitoring of these printed components using the strain and temperature sensors installed during printing. The sensing technology utilizes the Rayleigh backscatter pattern contained in an optical fiber to determine the strain or temperature, with a high spatial resolution of 1.28 mm, along a fiber that can be embedded inside a printed component. HD-FOS technology was used to measure internal residual strains within layers of varying depths of an ABS printed block, showing a parabolic strain profile with a peak at 9,600 microstrain. In addition to characterizing the printing process, a method has been demonstrated to embed a distributed temperature sensor into a metallic additively manufactured component. This enables the temperature of the part to be measured while it is in use, providing data on the heat transfer through the component. Additive manufacturing has enabled embedding fiber optic sensors in new configurations that were previously unobtainable.

Commentary by Dr. Valentin Fuster
2016;():V002T02A067. doi:10.1115/IMECE2016-66810.

This paper aims at creating a computational finite element model, which will be used for prediction of deformation and failure of specimen under static loads for specimens prepared using FDM based 3D printers with different raster fill patterns and density. The work is divided as follows: a) understanding heterogeneity in specimen printed using FDM; b) conducting strength testing experiments to estimate stiffness and failure corresponding to particular infill configuration; c) creating and validating computational finite element model of FDM printed specimen with various raster fill pattern and density. In this work, the computational model of FDM parts is created as a multi-layered composite model. The computational model generated in this work can be used to estimate the deformation of a specimen printed using FDM process under a specific load condition. This model can further be used within an optimization framework to maximize part strength for a part with any geometry by suitably selecting part orientation and slicing parameters for a given service load condition.

Commentary by Dr. Valentin Fuster
2016;():V002T02A068. doi:10.1115/IMECE2016-67220.

As Additive Manufacturing (AM) matures as a technology, modeling methods have become increasingly sought after as a means for improving process planning, monitoring and control. For many, modeling offers the potential to complement, and in some cases perhaps ultimately supplant, tedious part qualification processes. Models are tailored for specific applications, focusing on specific predictions of interest. Such predictions are obtained with different degrees of fidelity. Limited knowledge of model fidelity hinders the user’s ability to make informed decisions on the selection, use, and reuse of models. A detailed study of the assumptions and approximations adopted in the development of models could be used to identify their predictive capabilities. This could then be used to estimate the level of fidelity to be expected from the models. This paper conceptualizes the modeling process and proposes a method to characterize AM models and ease the identification and communication of their capabilities, as determined by assumptions and approximations. An ontology is leveraged to provide structure to the identified characteristics. The resulting ontological framework enables the sharing of knowledge about indicators of model fidelity, through semantic query and knowledge browsing capabilities.

Commentary by Dr. Valentin Fuster
2016;():V002T02A069. doi:10.1115/IMECE2016-67304.

Graphene nanoplatelets (GNPs) have many outstanding properties, such as high mechanical strengths, light weight, and high electric conductivity. These unique properties make it an ideal filler material for various composites. On the other hand, the development MMNCs (metal matrix nanocomposites) through additive manufacturing (AM) processes has become a major innovation in the field of advanced structural materials, owing to shorter production lead time, less material waste, high production flexibility. It is of great innovativeness to have the attractive features combined to produce GNPs reinforced MMNCs using AM techniques. In addition, metal components produced by laser assisted additive manufacturing (LAAM) methods usually have inferior mechanical properties, as compared to the counterparts by the traditional metal forming processes. To achieve optimized mechanical properties, the obtained MMNCs are subjected to various post treatment routines and the effect of post heat treatment on material properties is investigated. In this study, pure Inconel 718 and GNPs reinforced IN718 with 1.1 vol.% and 4.4 vol.% filler material are fabricated by selective laser melting (SLM). Room temperature tensile tests are conducted to evaluate the tensile properties. Scanning electron microscopy (SEM) observations are conducted to analyze the microstructure of materials and to understand the reinforcing mechanism. It is found that fabrication of GNPs reinforced MMC using SLM is a viable approach. The obtained composites possess dense microstructure and enhanced tensile strength. The strengthening effect and mechanisms involved in the composites are discussed. Solution treatments at three levels of temperature (940, 980, and 1020°C) for 1 hour period are carried out to evaluate the effect of the heat treatment on the material microstructure and therefore the resulted mechanical properties of the composite material. The results of samples with and without heat treatment are also compared. The experiments results indicate that that addition of GNPs into Inconel 718 results in significant strength improvement. Moreover, at any volume content of reinforcement, higher solution treatment leads to lower strength, mainly due to coarsened microstructure. The addition of GNPs effectively inhibits the grain growth during the post heat process and the average grain size is significantly refined compared to unreinforced samples. Moreover, through the investigation of various strengthening mechanisms, it is found that Orowan strengthening effect is small and can be neglected for both as-built and heat treated conditions. Load transfer effect is the dominating strengthening effect among all contributors and solution treatment significantly reduces thermal mismatch strengthening.

Commentary by Dr. Valentin Fuster
2016;():V002T02A070. doi:10.1115/IMECE2016-67708.

Additive Manufacturing (AM) is the process of joining materials ‘layer by layer’ to make products from Computer Aided Design (CAD) model data. AM processes support faster product realization for a wide selection in industries. The Material Extrusion (ME) process is an AM process that builds a product from thin layers of extruded filaments from a semi-melted material such as a thermoplastic. In commercial systems, the software automatically generates the tool paths for both the model and any necessary supports, based on the curve geometry and the specified build parameters. The interior fill rotates 90° between each layer. Automatically generating the tool path can be the biggest weakness for this process planning strategy. Voids and discontinuities have been observed after evaluating test specimens developed to explore mechanical characteristics. Choosing an optimal raster orientation and bead width will help minimize voids and discontinuities in each layer. A mathematical model is introduced in this paper to find optimal raster orientation and bead widths based on the geometry of the slice for selected 2D extruded parts. As well, preliminary quality assessment metrics are introduced. Void analysis is performed to evaluate solution approaches, and the results compared. The future work will investigate utilizing multiple bead widths for a layer to minimize voids, and developing more comprehensive quality metrics to highlight problematic regions.

Topics: Extruding
Commentary by Dr. Valentin Fuster

Advanced Manufacturing: Symposium on Advances in Joining Technologies for Engineering Materials and Structures

2016;():V002T02A071. doi:10.1115/IMECE2016-65156.

Friction stir welding (FSW) is a solid state welding process in which a non-consumable rotating tool with a specially designed pin and shoulder is inserted into the abutting edges of sheets or plates to be joined and subsequently traversed along the joint line. In FSW, a pin tool with different shapes spins against the edges of two metal pieces of same or different thickness positioned next to each other. As the pin travels along, it creates friction that generates heat, mixes, and joins the alloys without melting them. To optimize the process, several researchers created pins of different shape, and geometry, and used them in FSW but varied the depth, rotational speed, and tilt angle of the pins. Statistical analysis has been used to identify the most optimum combination of tool and weld parameters that could support high-speed production. Many studies support that the faster FSW is carried out, the stronger (better weld quality) the resulting welds will be.

The objective of this paper is to predict the effects of some of the process parameters on the performance of the aluminum alloy components joined using ANSYS simulation tool. Although not reported in this paper, the mechanical and metallurgical properties of the welded members have been measured in the laboratory. The goal is to gain an understanding of how FSW can be used to successfully join aluminum alloys and to study the effect of the various process parameters on the process. The material used is AA6061 as it is one of the popular choices for automotive applications. Experiments have been conducted to validate some of the simulation results from ANSYS software.

Commentary by Dr. Valentin Fuster
2016;():V002T02A072. doi:10.1115/IMECE2016-65530.

The present paper deals with the failure analysis of a pinion shaft belonging to a differential gear for offroad machinery applications, namely wheel loaders. The motivations of the study arise from some in-field failures, which resulted in the fracture of the pinion shaft, originated at an external groove located at the end of its threaded portion. The issue has been tackled by means of analytical, numerical and experimental tools. The observed failures have been demonstrated to be due to the in-service loosening of a ring nut, whose function is to preload the tapered rolling bearings, which support the shaft.

Commentary by Dr. Valentin Fuster
2016;():V002T02A073. doi:10.1115/IMECE2016-65654.

Laser cladding is a rapid physical metallurgy process with a fast heating-cooling cycle in which different compositions and properties of the alloy are melted on the surface of the substrate by the high-energy laser beams. This fabrication process method is accompanied with complex metallurgy and transformation processes. Numerical simulation tools can simulate the process of laser cladding, and optimize the parameters and predict the potential cladding defects of the cladding. In the present study, a three-dimensional finite element model was built for a powder-feed laser cladding model process. A transient temperature field was built, where the conical Gaussian distribution of moving heat source, conduction, convection, and radiation heat transfer are simulated. In the analysis, the temperature dependent material properties as well as the phase transformation behavior of the materials was taken into account. The addition of material is numerically carried out in a thermal-metallurgical-mechanical coupled manner. As a benchmark to validate the simulated model, experimental Vickers microhardness data was used and the observed bead shape of the specimen was compared to the simulation results. The finite element simulation was conducted by SYSWELD software. This paper will present the results of a study where P420 steel cladding powder (a steel commonly used in injection molding) which is deposited on low/medium carbon structural steel plates (AISI 1018) using the coaxial powder flow laser cladding method. The results reveal how the process parameters affect the distribution of the temperature, bead geometry, and strength.

Commentary by Dr. Valentin Fuster
2016;():V002T02A074. doi:10.1115/IMECE2016-65786.

Over the last few decades, lightweight material joints including plastics, aluminum, magnesium and various composites have been widely used in many mechanical and structural applications such as automotive, aircraft and so on, for their high strength-to-weight ratio and the significant improvement for the fuel economy and energy efficiency. Self-tapping screws are one of major technologies to connect the various joints and provide system integrity in ease of system assembly, low cost, etc. In this study, tightening performance of thread cutting screw in aluminum joints is evaluated. Effect of repeated tightening and loosening on the screw performance is investigated for the screw residual torque after environmental thermal cycling. Cyclic temperature fluctuates between 130°C and −20°C in a computer-controlled environmental chamber. Joint coupon materials are steel and aluminum material. Analysis of experimental data provides a useful insight into the self-tapping process into aluminum joints.

Topics: Aluminum , Steel , Screws
Commentary by Dr. Valentin Fuster
2016;():V002T02A075. doi:10.1115/IMECE2016-65797.

Friction stir welding (FSW) invented by TWI is a solid-state joining process, which is used to weld high-strength aluminum alloys and other metallic alloys which are non weldable by conventional fusion welding process. In this work, AA6063-O alloy of 150 mm in length, 75 mm in width and 6mm thickness is taken and friction stir welded in submerged condition in order to improve the joint properties. The chosen process parameters are tool pin profiles (cylindrical, threaded and tapered), rotational speed and welding speed. The process parameters are optimized with multi response characteristics including hardness and average grain size at the nugget zone. The traditional Taguchi approach is insufficient to solve a multi response optimization problem. Therefore, Grey Relational Analysis (GRA) is used in this current work. The optimal result indicates that the multi response characteristics of the AA6063-O during the submerged friction stir welding process can be enhanced through Grey Relational Analysis. In order to investigate the significance of process parameters, Analysis of Variance (ANOVA) is carried out. The mechanical properties and microstructure variation of both the normal FSW and submerged FSW joints are compared.

Commentary by Dr. Valentin Fuster
2016;():V002T02A076. doi:10.1115/IMECE2016-66005.

This contribution investigates the tightening behavior and preload loss of bolted joints with painted coating systems for corrosion protection of components. Friction coefficients are measured with test stand, preload loss is measured by strain gauges. Further evaluation is done with optical roughness measurement to see damage of the painted surfaces in contact areas. Resulting from this hints for applications get obvious. Research progress focuses the quantification of preload loss in different applications. Mechanical loads are neglected at that stage because of minor influence as the temperature.

To sum up, it can be formulated that the tested, robust coating systems can endure yield-point-tightening of high-strength screws and also exist as a complete and coherent layer after the loosening. Therefore corrosion protection could be guaranteed also after a yield-point-tightening, especially underneath the screw head. This is in particular relevant for applications which require repeated tightening of the same screw.

Corrosion protection layers within the flow of force usually change the friction coefficients compared with bare material. This effect influences the assembly of bolted connections dominantly. Controlling the assembly process is getting more difficult because of the increasing scattering from steering parameters, like torque or angle. There might be huge deviations, up to a factor of 6.2, between torque values of a similar assembly process. Therefore process safety cannot be guaranteed, especially if their values miss originally defined tolerances.

To overcome these difficulties it is necessary to use the right assembly method as well as the right coating system. After our opinion the yield-point controlled tightening is the only method which leads to a safe assembly preload, even with coated parts. If the preload loss will be acceptable depends on the coating system and the external conditions.

Commentary by Dr. Valentin Fuster
2016;():V002T02A077. doi:10.1115/IMECE2016-66083.

In this study, a coupled shear stress-diffusion model is developed for the analysis of adhesively bonded single lap joints by applying Fickian diffusion model to the adhesive layer. Differential equations of equilibrium are formulated in terms of adhesive material properties that are time and location-dependent. By invoking a Volkersen approach on the equilibrium equations, a shear stress differential equation is formulated, and numerically solved. Several scenarios are considered for investigating the effect of diffusion on shear stress distribution in adhesively bonded single lap joints. Detailed discussion of the results is presented.

Commentary by Dr. Valentin Fuster
2016;():V002T02A078. doi:10.1115/IMECE2016-66266.

A principal stress-based high cycle fatigue (HCF) model is proposed for cyclic multiaxial stresses in threaded fasteners under tensile-shear loading. The proposed model uses the fastener principle stress amplitude in order to construct mean-stress adjusted S-N curves for multi-axial stresses. Experimental validation is provided using an MTS fatigue testing system, with a special fixture that would allow combined cyclic tensile-shear loading of the fastener at various angles relative to the axis of the MTS grip axis. Experimentally validated multiaxial fatigue model is compared to classical uniaxial S-N curves. Detailed discussion of the model results is provided.

Topics: Fatigue , Stress , Fasteners
Commentary by Dr. Valentin Fuster
2016;():V002T02A079. doi:10.1115/IMECE2016-66336.

The calibrated wrench method is often used for tightening. When tightening bolted joints, it is important to apply high axial tension. However, since the axial tension is indirectly applied in this method, it varies and has a distribution in the case of tightening carried out in the production line of a factory, for example. However, the calibrated wrench method is still widely used because of the simple tool and easy standardization. In our previous papers, we analyzed and discussed the main points of this research by a theoretical approach as discussed below. Conventionally, this type of distribution has been considered to lie within a rhombus (more precisely, within a rectangular area). However, when considering the tightening torque and axial tension as independent random variables, the distribution becomes elliptical. The same idea applies to the relation between the tightening torque and the equivalent stress for a bolt axis based on shear strain energy theory. On the other hand, regarding the variation in the tightening torque (tightening work coefficient a) actually applied to a bolt, it was reported by Bickford, Kawasaki, and others that it can vary by 15% or more from the target (indicated) tightening torque. However, the torques for wrenches used at actual assembly sites or under lubricated conditions were not reported. Therefore, it is necessary to experimentally verify that the relation between the tightening torque and the axial tension (axial stress) and equivalent stress of a bolt axis is distributed in an ellipse. Furthermore, the screw-thread characteristics (torque coefficient, equivalent stress coefficient, coefficient of friction, etc.) during the tightening process should be clarified by an experimental approach and observation. Thus, in this study, in experiments under dry (as-obtained) and lubricated (Loctite 263) conditions, the tool (preset-type and dial-type torque wrenches) and bolt strength classification (8.8 and 10.9) were changed, and the screw-thread characteristics were observed during actual bolt tightening and the characteristics under different conditions were analyzed. It was clearly shown that the tightening torque and the axial tension (axial stress) of a bolt axis and the equivalent stress vary with an elliptical distribution rather than a rhombic distribution. Finally, the validity of the tightening theory based on the elliptical confidence limit method was also verified experimentally.

Topics: Bolted joints
Commentary by Dr. Valentin Fuster
2016;():V002T02A080. doi:10.1115/IMECE2016-66562.

The characteristics of bolted circular flange joints tightened with bolt number N are analyzed using FEM such as the interface stress distributions in initial clamping state, those in operation and the load factor under tensile loadings. Then the effects of the bolt pitch circle diameter D and the bolt number N on the load factor and the interface stress distributions are examined. The FEM results of the load factor and a load when the interfaces starts to separate are fairly coincided with the experimental results. The value of the load factor is the smaller and it is less than 0.1. In addition, it decreases as the value of D increases. Another objective is to demonstrate a new design method and two typical cases are described. One is a problem how to determine the bolt nominal diameter when the bolt strength grade, bolt number N, the interface stress for keeping the joint function and external load are provided and the other is how to determine the bolt strength when the bolt nominal diameter, interface stress and external load are provided. The measured tightening coefficient Q is introduced in the design and the bolt strength is evaluated using the newly introduced equivalent stress taking account the shear stress due to torque in bolt initial tightening. Using the obtained nominal diameter, the bolt maximum stress, the bolt stress amplitude and the critical stress at the bearing surfaces are checked. The availability of the method is shown with the flowchart for design.

Commentary by Dr. Valentin Fuster
2016;():V002T02A081. doi:10.1115/IMECE2016-66984.

Adhesive use in fastening is increasing in many industries. Modeling the behavior of adhesives allows joints to be optimized, decreasing costs from over-design and validation testing. Unfortunately, available adhesive material properties provided by manufactures are often insufficient to accurately model and predict behavior under real-world conditions. An adhesive joint in service is often subjected to a combination of mode I (tensile) and mode II (shear) loading. Also, when used in outdoor environments, ambient temperatures can vary from below freezing to over 40°C. This paper describes a project to measure the relevant adhesive material properties at the environmental conditions of interest for two specific adhesives and to use them in subsequent modeling. The needed material properties have been found to be mode I cohesive strength, mode I cohesive toughness, mode II cohesive strength, and mode II cohesive toughness. These properties are measured individually using four tests that isolate each of the material properties by using specimens with distinct geometries and loading conditions. These geometries allow the process zone of the adhesives to be controlled. A large process zone will relate to the cohesive strength, and a small process zone will relate to the cohesive toughness, in either mode I or mode II loading. Since the values of cohesive strength and toughness of the adhesives included in this study are unknown before testing, iterations of each specimen are varied by changing the process zone size to ensure valid properties are measured. Testing is conducted at −30°C, 20°C, and 45°C. In order to conduct this testing a temperature chamber was designed, fabricated, and validated. Commercially available temperature chambers were either too small or prohibitively expensive. The temperature chamber this project created was constructed of laser cut and bent stainless steel sheets with an insulated double-wall construction. Two seals were used at every entry point to maintain an air-tight chamber. A heating and cooling circulator and heat exchanger were used for temperature control. The chamber can heat to 45°C in approximately 15 minutes, and cool to −30°C in approximately 30 minutes.

Commentary by Dr. Valentin Fuster
2016;():V002T02A082. doi:10.1115/IMECE2016-67178.

Cold spray is a solid-state material deposition method that can create thick (>10mm) metal layers that adhere metallurgically to a base part or a substrate. Numerous potential applications exist, such as returning worn mechanical parts to their original dimension, extending their service life.

For fatigue applications the fracture properties of cold spray deposited material must be known but little to no literature has been found on the fracture behavior of cold spray deposited material alone, which prompted the study presented here.

Fracture toughness specimens were manufactured by depositing thick cold-sprayed layers of powdered aluminum 6061 onto an aluminum 6061 substrate using N2 as the carrier gas. The substrate was then machined away, and monolithic miniature compact tension fracture toughness specimens were machined from the cold spray deposit itself, following ASTM E-1820.

The fracture behavior of the cold sprayed material was then experimentally determined using the elastic-plastic J-resistance method for compact test specimens described in ASTM E-1820. Two specimen conditions were successfully tested, “as-sprayed” and “partially annealed”.

The results are that the Mode-I elastic-plastic stress intensity factor JI has been successfully measured for cold-spray deposited material alone, and that partially annealing a cold-spray deposit can dramatically increase its fracture toughness.

Commentary by Dr. Valentin Fuster
2016;():V002T02A083. doi:10.1115/IMECE2016-67359.

This study investigates the effect of key variable combinations on the loosening performance of a preloaded threaded fastener system under harmonic transverse vibrations, using a software for bolt loosening analysis. The software is based on a mathematical model of the standard Junker test for vibration loosening. Studied variable combinations include the fastener initial tension, thread pitch, bearing and thread friction coefficients, bolt stiffness, and joint stiffness. Generated data on bolt loosening performance is analyzed for trends and relative significance of variables, and variable combinations.

Topics: Fasteners , Vibration
Commentary by Dr. Valentin Fuster
2016;():V002T02A084. doi:10.1115/IMECE2016-67381.

In this study, the creep deformation in the threaded joint are discussed using a finite element method, and evaluated the influence of the dimensions of bolt and clamped parts. The stress and creep strain distributions are calculated using the Finite Element Analysis. The occurrence and the propagation of the creep deformation and influence of the creep deformation on the axial bolt force were discussed. It was found that the creep deformation occurred at the bearing surfaces and the engagement screw thread mainly at the elevated temperature. The creep deformation was a cause of the reduction in axial bolt force.

Commentary by Dr. Valentin Fuster
2016;():V002T02A085. doi:10.1115/IMECE2016-67427.

This study investigates the effect of cure temperature and pressure on the mechanical performance of autoclave-bonded single lap joints (SLJ). Joint load transfer capacity (LTC) and failure mode analysis are provided. Test joints are made of two polycarbonate lexan adherends that are autoclave-bonded together using aliphatic polyether (Polyurethane) film adhesive (Huntsman PE399). Two levels of cure pressure and cure temperature are investigated, for their effect on joint load transfer capacity and failure. Data analysis and discussion are provided.

Topics: Pressure , Temperature
Commentary by Dr. Valentin Fuster
2016;():V002T02A086. doi:10.1115/IMECE2016-67665.

Duplex stainless steel are excellent corrosion resistance two-phase alloy as compared to stainless steel. The corrosion resistance of duplex stainless steel depends upon the balance phase of ferrite and austenite. During non-equilibrium processes such as welding, the fast cooling rate (as compared to the controlled environment where it is produced) suppresses the austenite to ferrite transformation. A low frequency vibration assisted hot-wire Gas-Tungsten Arc Welding (GTAW) has been used to weld commercial duplex stainless steel alloy 2205. The results are compared with cold-wire GTAW weldments. The micro-hardness and microstructure of the weldments and heat-affected zones are characterized. A pitting corrosion test was performed on the weldments to measure the weight loss. A lower weight loss was achieved by using the low frequency vibration assisted hot-wire GTAW, however small pit was observed on the weld cap.

Commentary by Dr. Valentin Fuster
2016;():V002T02A087. doi:10.1115/IMECE2016-67890.

Generations of warfighters have benefited from field manuals to provide instructional knowledge for creating improvised devices and capabilities from readily available resources. These devices range from simple fundamentals to classified advances in materials and technologies. A collaborative effort between the United States Military Academy and the U.S. Army Armament Research, Development and Engineering Center is creating the latest repertoire of capabilities for soldiers in theater. An improvised electric arc welder was developed to provide field expedient capabilities to them. Both AC wall power and DC power from car batteries were utilized to demonstrate various options. This paper provides the electrical models, experimental results and lessons learned. Welds were tested in a tension tester to determine their viability.

Topics: Electric arcs
Commentary by Dr. Valentin Fuster
2016;():V002T02A088. doi:10.1115/IMECE2016-68156.

Friction Stir processing, a novel welding process which weld similar and dissimilar metals and alloys in solid state for joining metallic alloys and it has replaced conventional welding processes and have become an alternative welding technique. The commonly used aluminum alloys AA6061 and AA5086 were joined together using FSW. In this study, two parameters such as weld speed and tool rotation speed are taken into account. By varying these parameters the dissimilar alloys were welded together. The welded joints were analyzed for its chemical composition and phases formed due to heat produced by friction. The composition is characterized by Electron Back Scattered Diffraction technique (EBSD) and X-ray Diffraction technique (XRD). The influence of tool rotation speed and weld speed on texture has been studied.

Commentary by Dr. Valentin Fuster

Advanced Manufacturing: Visualization, Informatics, and Digital Manufacturing

2016;():V002T02A089. doi:10.1115/IMECE2016-65029.

The emergence of cyber physical frameworks has been catalyzed by various smart technologies including Next Generation Networks and 3D based Virtual Prototyping. Such frameworks hold the potential to support complex distributed collaborative practices in various engineering fields especially advanced manufacturing. This paper discusses the design and implementation of such a cyber physical framework based on Internet-of-Things (IoT) technologies while addressing semantic interoperability issues. The components of this framework is outlined along with an overview of the role of the emerging GENI based Next Internet technologies. The semantic framework is designed based on a Virtual Enterprise (VE) context where multiple organizations with similar as well as different capabilities can form temporary partnerships.

Commentary by Dr. Valentin Fuster
2016;():V002T02A090. doi:10.1115/IMECE2016-65926.

The effect of tool geometry on the quality of the machined part has been an important consideration. Here the effect of tool geometry from energy minimization angle has been studied for sustainable manufacturing. The greenhouse gas (GHG) emission has been analyzed in terms of rake angle (α) and shear plane angle (φ). A numerical study of tool geometry and its effect on eco-indicators has been presented. The shear force (Fs) decreases as rake angle increases. The reduction in horse power requirement will affect the GHG emissions. It has been quantified how much CO2 is emitted in air during machining. The other toxic gases like NOx, SO2, CH4, and mercury (Hg) emissions have also been quantified. The friction force (F) declines very rapidly as rake angle (α) increases and reduce the lubricant requirement. The total specific energy (TSE) is summation of specific process energy (SPE) and specific constant energy (SCE).

Topics: Geometry
Commentary by Dr. Valentin Fuster
2016;():V002T02A091. doi:10.1115/IMECE2016-68206.

We report our work-in-progress on a new method to train an industrial robot that can learn from the demonstrations of manufacturing tasks by a skilled worker (trainer). A parametrized learning engine is trained based on identifiable features of the trainer’s body and objects. To achieve this, we collected a large number of depth data. Different objects in the scene are clustered using Gaussian mixture model and are manually labelled. Features are engineered to train random decision forest. Feature engineering is required since the number of dimensions (number of depth points) of samples vary because of variations in depth capture. Depth samples are transformed to a lower dimension space of 96 dimensions defined by means and covariance of data distribution. This method has a classification accuracy of 80.72%. Using these features, the robot can identify parts in real-time, tag as well as track them as the trainer moves them during the demonstration. Our ongoing work is on semantic classification of the tracked data into high level actions which will be combined using a set of rules called action-grammar.

Topics: Robots , Manufacturing
Commentary by Dr. Valentin Fuster

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