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IN THIS VOLUME


ASME Conference Presenter Attendance Policy and Archival Proceedings

2012;():i. doi:10.1115/IMECE2012-NS3.
FREE TO VIEW

This online compilation of papers from the ASME 2012 International Mechanical Engineering Congress and Exposition (IMECE2012) 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to ASME’s conference presenter attendance policy, if a paper is not presented at the Conference, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.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

Design, Materials, and Manufacturing: Advances in Material Forming, Applications, Tooling and Rapid Prototyping

2012;():1-7. doi:10.1115/IMECE2012-85689.

AA7075 has many good mechanical properties; however, its bonding strength is poor and is difficult to produce extruded hollow products. Although some researchers proposed different method to study welding strength of Aluminum alloy, related study for high strength Aluminum alloy in hollow extrusion process is not enough. This study use DEFORM 3D finite element analysis software to simulate two different types of hollow extruding die configurations for square tube extrusion process, namely: type I welding position at the corners of the square tube and type II on the side faces. The welding strengths of these two kinds of extruded tube are studied by expanding test and tensile test. The service lives of these two extrusion die components are studied based on the die stress and die wear information. Some information about the study are as follows: ingot material is AA7075, ingot diameter is 127mm, the extruded tube outside dimension is 54mm × 54mm, thickness is 5mm, extrusion temperature is 480°C, and ramp speed is 0.5mm/s, die material is SKD61 with HRC48. Research results show that the maximum extrusion force for type II is greater than type I. The maximum equivalent die stress occurs in upper die rather than in lower die both for type I and II. However, the predicted die life for type II is greater than type I due to extrusion die design. The welding strength for type II square tube is about 300 MPa on each welding seam.

Commentary by Dr. Valentin Fuster
2012;():9-16. doi:10.1115/IMECE2012-86279.

The fabrication of complex ceramic components requires new processing methods that are able to produce components with intricate geometries and accurate dimensions. The accuracy of the finished ceramic component depends upon precise control of the green ceramic body dimensions and uniformity prior to sintering. The authors are investigating the application of the fugitive phase approach, where a sacrificial material is used to form cavities or channels in the finished ceramic component. This paper, a continuation of a previous work, examines the lamination step of the fugitive phase approach for ceramic fabrication. The lamination step is where the fugitive phase pieces are combined with the tape cast green ceramic pieces. The multilayer green body is pressed to laminate the ceramic tape and fugitive phase layers together. Topological complexity is greatly increased when the tape cast ceramic pieces are interspersed with fugitive phase pieces to build up a consolidated multilayer green body. This paper examines the movement of the fugitive phase pieces, viscoelastic deformation of the ceramic phase, the filling of voids, pressure gradients, and the rebounding that occurs when the green ceramic body is removed from the press. This information will be used to complement parallel experimental investigations of the fugitive phase approach to ceramic fabrication.

Topics: Ceramics , Modeling
Commentary by Dr. Valentin Fuster
2012;():17-21. doi:10.1115/IMECE2012-86413.

This work is a case study of applying Bayesian analysis, a statistical data method, in the design optimization of permanent test-bar mold. The permanent test-bar mold is used in casting foundry to examine the metal quality. Since the current standard test-bar mold suffers from shrinkage porosity which detracts from best properties, a modified design is recently proposed to improve the mechanical properties. In order to validate the new design, Bayesian data analysis method is utilized to analyze the experimental data from the two designs. The effects of the mold designs and casting process operational parameters on the mechanical properties of castings are compared. Main effect to the mechanical properties is identified based on the Bayesian analysis.

Commentary by Dr. Valentin Fuster
2012;():23-30. doi:10.1115/IMECE2012-86427.

The metal pressing process which is widely used in many industries has advantages over casting process for producing large and thick blades of Francis turbine. For the design of pressing process, blank design should be firstly performed to determine the dimension of the flat blank. In fact, the traditional trial and error approach is not applicable for the blade design for Francis turbines that is not standard because of the different hydraulic characteristics of a hydropower plant from site to site. The powerful computing technology makes it possible to desgn optimum blanks by numerical modeling and simulation. In this paper, the multi-step inverse finite element approach is investigated for blank design and an elasto-plastic model has been built by using the well-known software ANSYS. Unfolding tests with cylindrical sections have been carried out and the numerical results agree well with the analytical results. Thereafter, a large and thick blade of Francis turbine for hydropower plants has been successfully unfolded by the FE model. Finally, for ensuring the machining of the blade after the pressing process, a new contour is obtained by extending the boundary of the flat blank provided by the FE model.

Commentary by Dr. Valentin Fuster
2012;():31-38. doi:10.1115/IMECE2012-87297.

In Car Body Assembly Shops, Body in White (BIW), non-rigid sheet metal panels are assembled into car bodies. Depending upon the achieved degree of robustness in part and tool design, the produced items tend to deviate more or less from their nominal specifications. Catching eventual non-robust solutions early on in the development phases is important to minimize time-consuming, expensive testing and trimming activities late in the development- and industrialization phases. To meet these demands, there is today an increased use of virtual forming and assembly tools within the automotive industry. Significant amounts of research have been performed in the area of forming and assembly simulations, but there is still a need to find efficient working methods.

This study has focused upon how forming simulation results can be used in virtual assembly analysis. The predicted springback shapes (offset and variation) of the stamped panels are used in the assembly simulation to study the effects of the part variation when assembled, producing a sub-assembly. The method used is described, and the simulation results are reported. The case shows the potential of using forming simulation results in virtual assembly analysis. Furthermore, the strength of using the Principal Component Analysis technique to describe the part variation in assembly simulations is shown.

Commentary by Dr. Valentin Fuster
2012;():39-48. doi:10.1115/IMECE2012-87401.

One of the utmost challenges of hot aluminum extrusion is to design the die cavities, used to extrude thin-walled profiles, by considering the effective nitriding surface treatment of the die bearing surface in terms of nitride layer uniformity. In the present study, various AISI H13 steel samples (having commonly-used profile geometric features) are manufactured using wire EDM and subsequently nitrided using two-stage controlled nitriding treatment. The uniformity and depth of nitride layers formation on these are investigated in terms of compound layer and total nitride case depth using optical and scanning electron microscopes. Finite element code ABAQUS is used to simulate the nitrding process using sequentially coupled thermo-diffusive analysis in line with experimental set up. Both experimental and numerical results are found in close agreement in terms of nitrogen concentration and corresponding micro-hardness profiles. Some design modifications are implemented in FE code for critical die profile features for uniform nitride layer development. In view of the current results, some design guidelines are suggested for effective and uniform nitride layer formation in order to secure high quality extruded product and extended die life.

Commentary by Dr. Valentin Fuster
2012;():49-58. doi:10.1115/IMECE2012-87654.

With the spread of endoscopic interventions the postoperative stress for patients has been reduced clearly. These interventions through natural orifices of the body (Natural orifice transluminal endoscopic surgery: NOTES) need miniaturized instruments with high precision, high range of motion and a high force load transmission.

Our aim is to develop a mechatronic, single-port robotic system to guide and move flexible endoscopic instruments and optics inside the body. The system should be adapted to a flexible endoscope and consists of two flexible and actuated end-effectors that carry and manipulate flexible instruments. Due to the flexible end of the structure, laparoscopic single-port surgery through one incision and endoscopic surgery through a natural orifice would be possible. The concepts and prototypes were realized by selective laser sintering (SLS). One way to create flexible structures for a single use robot is to use universal joints assembled together in series. Next, selective laser sintering can now print these parts with the joints already assembled, in one part. There is no need for assembling or adhesive bonding. The final step is to replace the real joints of the cardan shafts with elastic joints.

The proposed joints are made by the powder PA 2200 based on nylon. This basic powder is certificated as biocompatible according to ISO 10993-1. The challenge in this new field of printed medical robotics is to define a manufacturing process that enables you to design a part, create it by SLS and get it approved as a medical product.

Topics: Lasers , Robots , Sintering , Design
Commentary by Dr. Valentin Fuster
2012;():59-65. doi:10.1115/IMECE2012-88277.

Aerospace companies use high-strength metal alloys like Inconel or Titanium which could be very difficult to fabricate using conventional methods. The current manufacturing techniques result in significant waste. Additive Manufacturing (AM), in its current state is not sufficiently understood, nor characterized such that conventional design practices and process qualification methodologies can be used. In addition, AM cannot be considered for the manufacture of aircraft components unless the process is stable and controlled. The mechanical properties of fabricated parts require to be characterized to demonstrate their invariability. The laser deposition using complex geometries is a challenge. In addition, the structural performances of AM parts have to be proved. Inherent in these requirements is the need to develop a process specification which requires the monitoring and control of key raw materials, consumables, and process parameters; the development of a fixed practice for each of the AM process. Several procedures are required in order to understand how additive manufacturing works using advanced and complex design models. The ability to adopt AM to the production of components is not only predicated on the ability of AM to be competitive with conventional manufacturing methods in terms of cost, but also on its ability to deliver parts with repeatable mechanical performance. The objective of this paper is to define and characterize the limitation of various complex geometries using additive manufacturing. The experimental research involved the creation of a number of specimens using direct metal laser sintering process, examination of their form features, documenting DMLS geometry limits for the form features and finally the creation of calibration models that can be used in aerospace design manuals.

Commentary by Dr. Valentin Fuster
2012;():67-74. doi:10.1115/IMECE2012-88476.

In the direct digital metal manufacturing, Electron Beam Additive Manufacturing (EBAM) has been used to fabricate sophisticated metallic parts, in a layer by layer fashion, by sintering and/or melting metal powders. In principle, EBAM utilizes a high-energy electron beam to melt and fuse metal powders to build solid parts with various materials, such as Ti-6Al-4V which is very difficult to fabricate using conventional processes. EBAM is one of a few Additive Manufacturing (AM) technologies capable of making full-density metallic parts and has drastically extended AM applications.

The heat transfer analysis has been conducted in a simple case of a single-scan path with the effect of powder porosity investigated. In the actual EBAM process, the scan pattern is typically alternate raster. In this study, a coupled thermo-mechanical finite element model was developed to simulate the transient heat transfer, part residual stresses of alternate raster during the EBAM process subject to a moving heat source with a Gaussian volumetric distribution. The developed model was first examined against literature data. The coupled mechanical simulation is able to capture the evolution of the part residual stresses in EBAM.

Commentary by Dr. Valentin Fuster
2012;():75-76. doi:10.1115/IMECE2012-89107.

In this paper different cold forging processes of spiral bevel gear are studied based on the patent analysis. First of all, various design concepts are analyzed and classified according to the type of raw material and the motion of die during the forming process. Then, focused on the bulk billet, the parameters such as the mode of die motion, the size and shape of initial billet, the speed of punch and the coefficient of friction are selected to study their effects on the cold forging process. Finally, following the Taguchi method, numerical simulations are carried out to find out the suitable combination of process parameters. Material flow, stress and strain distributions as well as forging load are analyzed.

Commentary by Dr. Valentin Fuster
2012;():77-87. doi:10.1115/IMECE2012-89573.

The powder concentration distribution is a key factor which affects the powder catchment efficiency, laser attenuation and, consequently, the molten pool morphology in laser cladding. A cladding technique (via a hollow laser beam with a central powder delivery system), called inner powder feeding, is presented, which can greatly increase the powder utilization. According to the structure of laser head used for inner powder feeding, a three-dimensional numerical model is developed to simulate the gas-powder flow. The influences of the carrier gas flow rate, the shielding gas flow rate, and the geometry of the gas nozzle on powder concentration distribution are investigated. An observation system is developed to capture a particle distribution image. The gray values of the particle images show that their distributions coincide with the numerical results. The model also predicts the powder catchment efficiency. Single track deposition experiments are performed and the results are compared with a four-nozzle coaxial powder feeding system.

Commentary by Dr. Valentin Fuster

Design, Materials, and Manufacturing: CAD, CAM, and CAE Simulations

2012;():89-96. doi:10.1115/IMECE2012-85788.

Modern assembly lines for mass production need to fulfill several important criteria. One of them is to produce products with high geometrical quality (small geometric variation). For sheet metal assemblies, focused on in this paper, it is a very complex process to achieve good geometrical quality due to the large number of assembly steps and the geometrical variation (tolerances) of the incoming parts. One “golden rule” for sheet metal assembly lines is to always reuse fixturing points (locators) throughout the whole assembly line to minimize the geometrical variation and also the complexity of root cause analysis.

A new method to measure the complexity in an assembly line has been developed and also implemented in a commercial software for Computer Aided Tolerancing. This new tool not only demonstrates the “golden rule” but could also be used to ensure minimum geometrical complexity in assembly lines to ensure controlled production and high quality products.

Topics: Assembly lines
Commentary by Dr. Valentin Fuster
2012;():97-104. doi:10.1115/IMECE2012-86267.

The objective of this study was to explore how assembly ergonomics issues were regarded by geometry engineers. Therefore, 21 geometry engineers in two manufacturing companies were interviewed. Their answers show good awareness of the implications of poor assembly ergonomics but appropriate working procedures and support in CAT (Computer Aided Tolerancing) tool are missing. 95% of the respondents would like to add consideration to assembly ergonomics in their CAT simulation. Based on this study a number of assembly factors that need to be included and considered in locating scheme definition and geometric stability analysis are identified and presented. Altogether, the results show a need for organizational change and CAT tool development.

Commentary by Dr. Valentin Fuster
2012;():105-112. doi:10.1115/IMECE2012-86296.

This paper presents a standing wave piezoelectric ultrasonic using a flexural vibration transducer. The motor consists of three main parts, stator, rotor and sliding element. The stator is a single piezoceramic flexural vibration bar. The rotor is made up of the motor driving wheel and the shaft. A computer simulation and modelling using finite element analysis for the proposed motor is discussed and used in the motor design development process. Finite element analysis has been used to evaluate the motor structure by performing an algebraic solution of a set of equations, describing an ideal model structure, with a finite number of variables. The established simulation and modelling for ultrasonic motor using finite element analysis enabled to select, the material of the flexural transducer, defining the operating parameters for the motor, determining the principles of motion and proposing an innovative technique to control the direction of motion, by controlling the phase between the two modes of vibrations. This enabled to create two directions of motion from a single vibration bar. A prototype of the proposed motor was fabricated and measured. This showed that operating parameters of the fabricated prototype are: frequency equal to 40.7 KHz, voltage: 50: 100 volt and current: 50: 100 m-amperes. This is showed a close agreement with FEA. Typical output of the prototype is no-load travelling speed of 28 mm/s, a resolution on the order of micrometers and a dynamic response <100 μsec. The motor is able to carry a load equal to 0.78 Newton. The developed motor has been used successfully in EDM industrial applications.

Commentary by Dr. Valentin Fuster
2012;():113-117. doi:10.1115/IMECE2012-86820.

In the field of aircraft manufacturing, the conventional six-point location principle and relevant process equipment and technology can hardly meet the requirements of high efficient and high precision machining of large-scale thin-walled workpieces. To solve positioning problems of aircraft large-scale thin-walled workpieces in its machining and assembly process, a flexible positioning tooling system is appeared and based on which the multi-point positioning method is developed to optimize the number, location and clamping force of the vacuum heads of flexible tooling system. By numerical simulation, an example is presented to verify the effectiveness of the positioning optimization method. Finally, numbers of experiments for thin-walled workpieces were carried out to validate the positioning optimization method and the numerical example. Test data show that the FEA method used in this paper can accurately reflect the deformation of the workpiece, and the deformation of the workpiece after positioning is minimized and the stiffness is maximized with the positioning optimization method when using flexible positioning tooling system.

Commentary by Dr. Valentin Fuster
2012;():119-124. doi:10.1115/IMECE2012-86964.

Selective Laser Melting process (SLM) is an important manufacturing method for producing complex geometries which allows for creation of full density parts with similar properties as the bulk material without extensive post processing. In SLM process, laser power, beam focus diameter, and scanning velocity must be precisely set based on the material properties in order to produce dense parts. In this study, Finite Element Analysis (FEA) method is employed in order to simulate and analyze a single layer of 904L Stainless Steel. A three-dimensional transient thermal model of the SLM process based on phase change enthalpy, irradiation scattering, and heat conductivity of powder is developed. The laser beam is modeled as a moving heat flux on the surface of the layer using a fine mesh which allows for a variation of the shape and distribution of the beam. In this manner, various Gaussian distributions are investigated and compared against single and multi-element heat flux sources. The melt pool and temperature distribution in the part are numerically investigated in order to determine the effects of varying laser intensity, scanning velocity as well as preheating temperature. The results of the simulation are verified by comparing the melt pool width as a function of power and velocity against the experimentally obtained results. Lastly, 3D objects are fabricated with a SLM 50 Desktop machine using the acquired optimized process parameters.

Commentary by Dr. Valentin Fuster
2012;():125-130. doi:10.1115/IMECE2012-87086.

The problem of nonlinear bending of beams has been of special interest to many engineering mechanics researchers through the years. In the presented paper, the development of an interactive Graphical User Interface (GUI) module for investigating large deflections of circular shaped flexible beams subjected to an end concentrated load is discussed. The numerical computations in the developed module are performed using various special tools available in MATLAB. The module employs the GUIDE (Graphical User Interface Development Environment) feature of this software package to allow the user to interactively prescribe various beam and loading parameters to generate the output in the desired form. Even though MATLAB is widely used in many educational institutions and corporations all across the world, the utility of the GUIDE feature of this powerful tool is relatively unrecognized or underutilized. The developed module can serve as an effective and invaluable tool for the design of flexible beams.

In an earlier paper of the author published in the proceedings of the 2009 ASME International Mechanical Engineering Congress and Exposition (IMECE), the development of a toolkit created using LabVIEW for determining multiple equilibriums configurations of straight cantilever beams subjected to inclined end loads were discussed. The present paper additionally compares and contrasts some of various important features of these two premier engineering software tools (MATLAB & LabVIEW) while presenting the solution for this new problem. The paper can be of special interest not only to the researchers specifically interested in the problem of large deformations of flexible structural components, but also to those searching to find a perfect tool to investigate other class of engineering problems.

Commentary by Dr. Valentin Fuster
2012;():131-139. doi:10.1115/IMECE2012-87291.

Structural design for crashworthiness is a challenging area of research due to large plastic deformations and complex interactions among diverse components of the vehicle. A notable idea in topology optimization is the hybrid cellular automaton (HCA) method capable of topology synthesis for crashworthiness design. The HCA algorithm was inspired by the structural adaptation of bones to their ever changing mechanical environment. This methodology has been shown to be an effective topology synthesis tool.

The objective of this investigation is to examine the convergence and algorithm factors analysis of topology optimization for crashworthiness based on hybrid cellular automata paradigm. The orthogonal test is also proposed to study the effects of the algorithm factors on the dependent variables of the structure with new optimized topology. To demonstrate the convergence properties influenced by factors of the HCA algorithm in dynamic problems, the HCA framework is developed to a methodology for crashworthiness, which combines transient, non-linear finite-element analysis and local control rules acting on cells, and some simple cantilevered beam examples are utilized.

Commentary by Dr. Valentin Fuster
2012;():141-148. doi:10.1115/IMECE2012-87489.

At the aim of alleviating the computational burden of complicated engineering optimization problems, metamodels have been widely employed to approximate the expensive blackbox functions. Among the popular metamodeling methods RBF metamodel well balances the global approximation accuracy, computational cost and implementation difficulty. However, the approximation accuracy of RBF metamodel is heavily influenced by the width factors of kernel functions, which are hard to determine and actually depend on the numerical behavior of expensive functions and distribution of samples. The main contribution of this paper is to propose an optimized RBF (ORBF) metamodel for the purpose of improving the global approximation capability with an affordable extra computational cost. Several numerical problems are used to compare the global approximation performance of the proposed ORBF metamodeling methods to determine the promising optimization approach. And the proposed ORBF is also adopted in adaptive metamodel-based optimization method. Two numerical benchmark examples and an I-beam optimization design are used to validate the adaptive metamodel-based optimization method using ORBF metamodel. It is demonstrated that ORBF metamodeling is beneficial to improving the optimization efficiency and global convergence capability for expensive engineering optimization problems.

Commentary by Dr. Valentin Fuster
2012;():149-158. doi:10.1115/IMECE2012-87537.

Welding is widely used in industry for products made of joined sheet metal parts and beams. The virtual prototyping process of welds in standard CAD systems relies on functionalities to manually add weld beads to the assembly models. Weld beads can be in the form of symbolic annotations or 3D solid representations. The size of products in terms of number of parts and required weld beads makes this process cumbersome and time consuming.

This paper presents a method to analyze CAD models of product assemblies in order to automatically identify possible welds among the parts using geometric recognition rules. Adjacent faces are detected and Boolean operators on planar loops are used to identify bead paths. Beads are then split in homogeneous portions based on the topology of the connected parts. The geometrical analysis of the connected parts also allows a bead to be characterized in terms of thickness, type, length and accessibility. Finally, the user is provided with functionalities to edit manufacturing properties or exclude unwanted welds.

The approach is applied at the design stage to rapidly come to the definition of the welds. If integrated with a CAD tool, this can be used as input for an efficient detailing phase. Moreover, the paper presents an application for the cost estimation of the designed welded product. Weld beads are given a realization time, and hence a cost, based on their geometric size and employed welding technology. Some examples from the industry are presented to show benefits in terms of time savings and accuracy of the cost estimation process.

Topics: Welding
Commentary by Dr. Valentin Fuster
2012;():159-168. doi:10.1115/IMECE2012-87703.

Double submerged spiral-welded pipe (SWP) is used extensively throughout the world for large-diameter pipelines. Fabrication-induced residual stresses in spiral welded pipe have received increasing attention in gas, oil and petrochemical industry. Several studies reported in the literature verify the critical role of residual stresses in the failure of these pipes. Therefore, it is important that such stresses are accounted for in safety assessment procedures such as the British R6 and BS7910. This can be done only when detailed information on the residual stress distribution in the component is known. In industry, residual stresses in spiral welded pipe are measured experimentally by means of destructive techniques known as Ring Splitting Test. In this study, statistical analysis and linear-regression modeling were used to study the effect of several structural, material and welding parameters on ring splitting test opening for spiral welded pipes. The experimental results were employed to develop an appropriate regression equation, and to predict the residual stress on the spiral welded pipes. It was found that the developed regression equation explains 36.48% of the variability in the ring opening. In the second part, a 3-D finite element model is presented to perform coupled-field analysis of the welding of spiral pipe. Using this model, temperature as well as stress fields in the region of the weld edges is predicted.

Commentary by Dr. Valentin Fuster
2012;():169-179. doi:10.1115/IMECE2012-88067.

This paper presents the development as well as the architecture of a computer-aided dedicated fixture design system intended to support the design of lightweight (carbon fiber composite) grippers for a major truck company. Lightweight grippers were required due to the increasing production rates in the automotive industry. The current robotic equipment was facing diverse problems during transportation and aligning of the parts, problems related to mass inertia, accuracy and stability. Moreover, the increased demands for truck customization and fast release of new product versions required a computer-based support for the design of the appropriate fixtures.

This application is believed to be of interest for fixture research because the design of such complex fixtures is likely to appear more and more often. Specifically, such fixtures are subject to specific requirements that necessitate a systematic requirement elicitation method; they also require extensive conceptual design work as well as careful analysis activity planning.

The main steps requisite for the development of the design system are reported: setup planning, fixture planning, conceptual design of the gripper. The architecture, the process and the constituent elements of the design system are also described and illustrated.

Commentary by Dr. Valentin Fuster
2012;():181-186. doi:10.1115/IMECE2012-88263.

Computer algebra systems (CAS) have been advantageously employed to generate closed form expressions for finite elements. The advantages relate to the time improvements or savings realized by employing closed form generated expressions as compared to numerical integration. However as the element order increases, the size of the closed form generated expressions become unmanageable causing the source code files to possibly become unusable due to their size. One approach to reducing the size of the source files is to take advantage of the utilities found in CAS to identify common expressions or sub-expressions. In this manuscript we present on-going research by comparing two widely used CAS, Mathematica and Maple, as they relate to identifying common expressions in low order tetrahedral finite element stiffness matrices generated in symbolic form, associated time savings and possible issues. The results indicate that the use of CAS could be advantageously employed to identify common subexpressions through pattern matching to further reduce the size of the generated source files and realize time improvements during execution of the source codes. In addition, the developed procedures could be easily applied to higher order elements with much larger number of entries of closed form expressions where even more savings could be realized.

Commentary by Dr. Valentin Fuster
2012;():187-198. doi:10.1115/IMECE2012-88505.

This work presents the development of a toolkit for the analysis and design of composite pressure vessels. The toolkit is developed in APDL (ANSYS parametric design language) to work inside ANSYS. In addition to the macros in APDL, a graphical user interface is developed in Tk/Tcl to access the toolkit. The toolkit includes a tool for composite material analysis with the method of cells, developed and implemented to get laminae properties from fiber and matrix properties. A shell elements tool and a hexahedral elements tool were implemented to generate 3D type 3 (metal lined) or type 4 (plastic lined) fiber reinforced pressure vessel models. A mixed Tsai-Wu and maximum stress tool was also implemented in the toolkit to predict composite failure. In addition to these tools, there are two scripts to model honeycomb as well as an algorithm to perform a netting analysis.

Commentary by Dr. Valentin Fuster
2012;():199-203. doi:10.1115/IMECE2012-88552.

Micro-drilling with spacing intervals in the hundred micrometer range is an essential process, however suitable methods are lacking despite efforts to develop useful strategies for precision micro-drilling. For efficiency, printed circuit boards are stacked in several layers and drilled through simultaneously but the process results in misalignment of holes as observed between consecutive layers from top to bottom. The work herein proposes a new tool path strategy in comparison with conventional methods. Hole positioning, drilling thrust force, and duration time were measured and evaluated. This strategy can be utilized in micro-manufacturing process for improving machining stability and productivity.

Topics: Stability , Drilling
Commentary by Dr. Valentin Fuster
2012;():205-210. doi:10.1115/IMECE2012-88553.

An experimental study and a numerical simulation of friction stir welding (FSW) process on aluminum 6064 plates is presented. The numerical analysis is performed using finite element technique with LsDyna software and the Aleatory Lagrangian Eulerian (ALE) formulation. Input parameters on the FEM are the mechanical properties of the aluminum 6064 as workpiece and H13 steel properties as the tool. The finite element analysis results shown Von Mises stresses and plastic strain developed during the process. An experimental analysis was conducted with the variation of process parameters and the specimens obtained were evaluated by x-ray inspection, tensile tests, and hardness measurements.

Commentary by Dr. Valentin Fuster
2012;():211-216. doi:10.1115/IMECE2012-88592.

Pipe flanges are usually welded or screwed to the pipe end and are connected with bolts. This approach is very simple and widely used for a long time, however, it results in high development cost and low productivity and some safety problems at the welding area. In this research, a new approach of forming pipe flange based on cold forging and floating die concept is presented. This innovative approach increases the effectiveness of the material usage and save the time cost compared with conventional welding method.

To ensure the dimensional accuracy of the final product, finite element analysis are carried out to simulate the process of cold forging, and orthogonal experiments method are used to investigate the influence of four manufacturing factors and predict the best combination of them. In addition, a real product is manufactured in terms of the best factors predicted by FEA and optimization method to validate the proposed approach. The experimental results show that the approach is effective for the forming of pipe flange, and can be widely used later.

Commentary by Dr. Valentin Fuster
2012;():217-222. doi:10.1115/IMECE2012-89101.

The necessity of a demonstration test to evaluate the structural integrity of a basket for accident conditions arose during the license approval procedure for the WSPP’s dry storage facility, called MACSTOR/KN-400. A drop test facility for a demonstration was constructed at the KAERI (Korea Atomic Energy Research Institute) site, and demonstration tests for a basket drop were conducted. As the upper welding region of the loaded basket collided with the dropping basket during the drop test, the welding in this region was fractured and a leakage occurred after the drop test. An enhancement of the basket design is needed since the existing basket design was not able to satisfy the performance requirement. The directions for the design modification were determined and six enhanced designs were derived based on these directions. Structural analyses and specimen tests for each enhanced design were conducted. By evaluating the structural analysis and test results, one among six enhanced designs was decided as a final design for revision. The final design was the one that reduced the height of the central post of the basket and decreased the impact velocity with the dropping basket. Test basket models were fabricated in accordance with the final enhanced design. An additional demonstration test was performed for this test model and all the performance requirements were satisfied.

Commentary by Dr. Valentin Fuster
2012;():223-232. doi:10.1115/IMECE2012-89247.

This paper considers the design of a high speed mechanism as a multi objective optimization problem wherein the kinematic and dynamic criteria are optimized simultaneously. The kinematic criteria include minimization of the structural error and a minimization of deviation of the transmission angle from its ideal value. The dynamic criteria include minimization of input driving torque and shaking forces transmitted to the ground link. A Stackelberg (leader-follower) game theoretic approach is proposed to solve the multiobjective problem. Two variants, wherein both the kinematic and the dynamic criteria are treated as the leader, are considered. The design variables include mechanism dimensions and counterweight parameters. A partitioning of the design variables amongst the leader and follower objective functions is discussed. A computational procedure using sensitivity information is used for approximating rational reaction sets needed for capturing exchange of information between the leader and the follower problems. A numerical example dealing with the design of a path generating 4-bar mechanism is presented.

Commentary by Dr. Valentin Fuster
2012;():233-240. doi:10.1115/IMECE2012-89452.

This paper presents the research work on developing a virtual sculpting system with haptic interface integrated with PowerWall system for complex product design. The PowerWall is a large scale (10 ft by 7.5 ft) immersive Virtual Environment (VE). The approach is to apply virtual sculpting method by interactively carving a workpiece using a virtual tool. With the implementation of stereoscopic visual feedback and haptic force feedback in the PowerWall, the designer would appreciate a much better understanding of the 3D shape geometry and can explore through the 3D scene like he/she can do in the real world. The “hybrid interaction technique” is presented as solution to solve the mismatch between the small workspace of the haptic device and the large size of PowerWall system.

Commentary by Dr. Valentin Fuster
2012;():241-249. doi:10.1115/IMECE2012-89475.

In the current globalized and competitive business world it has become increasingly more important that companies adapt their knowledge bases, in order to establish more dynamic business partnerships. However, one of the main problems found in the establishment of such partnerships has to do with the lack of interoperability between technologic systems, especially those related to the semantic of shared knowledge. The integration and sharing of the knowledge representation elements of companies, performs a key role in the research challenges in the business interoperability area.

The paper presents a methodology to analyse the economic viability of companies in the needed effort to the conception of a common knowledge base in their operational domain area, in order to stimulate interoperability in the business cooperation. These studies also have as objective to support the development of the thesis that argues that in the future, the capability to adapt the semantics of business information systems will promote collaboration between companies, providing them new business opportunities.

Commentary by Dr. Valentin Fuster
2012;():251-260. doi:10.1115/IMECE2012-89522.

Structural analysis is a critical aspect in the successful design of tube launched projectiles, such as mortar rounds. Ongoing research conducted at West Virginia University has focused on a Hybrid Projectile (HP), folding-wing UAV design inspired by mortars. This has driven the necessity of a structural analysis of the prototype design to provide vital feedback to designers to ensure that the HP is likely to survive the act of launching. Due to the extreme accelerations during the launching phase, a typical mortar round experiences dramatic impulse loads for an extremely brief duration of time. Such loads are the result of the propellant combustion process. Thermodynamic-based interior ballistic computations have been formulated and were used to solve the dynamic equations of motion that govern the system. Modern ballistic programs solve these equations by modeling the combustion of the propellant. However, mathematical procedures for such analyses require complex models to attain accurate results. Consequently, the objective of this research was to create a ballistic program that could evaluate interior ballistics by using archived pressure-time data without having to simulate the propellant combustion. A program routine created for this purpose reduces the complexity of calculations to be performed and minimizes computational effort, while maintaining a reasonable degree of accuracy for the motion dynamics results (temporal position, velocity, acceleration of the projectile). Additionally, the program routine was used to produce a mathematical model describing the pressure as a function of time, which could be used as loading conditions for more advanced explicit-dynamic finite element simulations to evaluate the transient response and stress wave propagation of the prototype and individual payload components. Such simulations remove uncertainties related to the transient loads needed to assess the structural integrity of the projectile and its components.

Commentary by Dr. Valentin Fuster
2012;():261-264. doi:10.1115/IMECE2012-89759.

There is an industrial demand for the increased performance of mechanical power transmission devices. This need in high performance is driven by high load capacity, high endurance, low cost, long life, and high speed. New designs and modifications in gears have been investigated to obtain high load carrying capacity and increased life with less volume and weight. Tooth wear is one of the major failure modes in gears. Although there are different classifications of wear mechanisms, wear on gears can be simply classified as mild wear, pitting, and severe wear, depending on the wear rate. These types of wear may lead to power transmission losses, decreased efficiency, increased vibration and noise, and gear tooth failure. This paper deals with the simulation of wear for standard and non-standard gears using an analytical approach. A numerical model for wear prediction of gear pair is developed. A wear model based on Archard’s equation is employed to predict wear depth. A MATLAB-based virtual tool is developed to analyze wear behavior of standard and non-standard spur gears with various gear parameters. In this paper, this virtual tool is introduced by using many numerical examples.

Topics: Wear , Simulation , Spur gears
Commentary by Dr. Valentin Fuster

Design, Materials, and Manufacturing: Design and Manufacturing of Aerospace, Transportation and Food Industry Applications

2012;():265-273. doi:10.1115/IMECE2012-85269.

Optimizing the design of the mechanical transmission elements in a servo-drive system has a profound effect on its dynamic performance; the acceleration capability. Servo-drive systems can be classified, according to the type of its inertial load, into rotary and translatory systems. Accordingly, the components of the transmission system mainly include a gear set and/or a ball-screw. In this paper the effect of the mechanical transmission characteristics (moments of inertia, gear set reduction ratio and ball-screw pitch) on the acceleration capability of the servo-drive system is investigated. Three gear schemes are presented in order to describe the variation of the gear set moment of inertia as function of its reduction ratio. In the first gear scheme, the driving pinion dimensions and moment of inertia remain constant, while the driven gear wheel pitch circle diameter increases as the gear set reduction ratio increases. The second gear scheme assumes a fixed center distance between the pinion and gear wheel for any gear set reduction ratio. Finally, the third gear scheme expresses the mass moment of inertia of the pinion and the gear wheel as a function of the gear set reduction ratio and the mass moment of inertia of the pinion at unity gear ratio. A generalized relation, applicable to any gear scheme, between the pinion moment of inertia at unity reduction ratio and the applied torque is presented. The effect of the choice of the gear scheme on the acceleration capability of the rotary and translatory servo-drive systems is investigated and compared. The paper provides the servo-system designer with means for integrating the “variable” reduction gear characteristics into the mechanical model in an adaptive manner.

Commentary by Dr. Valentin Fuster
2012;():275-288. doi:10.1115/IMECE2012-85471.

This paper articulates the potentials and limitations of the existing techniques for adapting product information contents for transmission among heterogeneous terminal devices and networks. The principal aim of the work was to understand, through a literature survey and empirical investigations, the affordances of the existing content adaptation techniques with a view to using handheld devices in performing product development tasks. Specifically, we reviewed and analyzed a wide range of the existing and emerging content adaptation techniques. The review has both revealed the potentials and shortcomings of the prevailing content adaptation strategies, and also has raised several questions for further research. Among the main shortcomings include lack of suitable mechanisms for adapting some specific contents used in product development such as for adapting 3D product models in context; and the inability of the existing mechanisms to guarantee the synchronization of both the meaning and the context of the content among heterogeneous terminal devices whilst meeting both resource constraints and task requirements. We have also identified the characteristic features we expect an ideal content adaptation mechanism to encompass, and used them as the basis for assessing the extents to which the existing techniques meet the adaptation requirements in product development. A concept and a generic architecture for content adaptation in a product development environment have subsequently been proposed. Overall, the existing content adaptation solutions provide only a subset of the desirable functional features. What is needed is a comprehensive adaptation mechanism, which among other things, handles 3D models and other types of product data; guarantees the synchronization of both the context and the meaning of the information content; considers the constraints posed by the heterogeneity of terminal devices and networks, and which at the same time also takes into account the task requirements and the specific needs and preferences of the users (who in the context of the work reported in this paper are the designers and engineers).

Commentary by Dr. Valentin Fuster
2012;():289-296. doi:10.1115/IMECE2012-85906.

Increasingly electric vehicle design is looking forward the application of multiple ratio transmissions in place of traditional single ratio gearboxes. The choice of gear ratio has significant influence on vehicle performance, including range, acceleration, and gradeability. To study the impact of different transmissions on EV’s dynamic and economic performance, mathematical models of an EV is presented which is applicable to both single and multiple ratio transmissions. These transmission variants are then studied under different operating conditions to investigate how operating conditions in the motor work efficiency change with different transmissions. Here comparisons are made between 2-speed and single speed transmission. Then the reasons for the results are analysed.

Commentary by Dr. Valentin Fuster
2012;():297-304. doi:10.1115/IMECE2012-86507.

This paper demonstrates the investigation carried out into the influence of ultrasonic servo feed drive technology, in electro discharge processing systems, industrial applications. The drive was mainly designed to replace the existing servo control drive using electromagnetic servo technology. This was aimed to improve the electro discharge servo control system stability, quality of the machined products surface profiles, and system dynamic time response. Evaluation has been undertaken to examine the developed servo control feed drive, in two industrial applications, electro discharge machining and electro discharge texturing. Two arrangements were used, in this investigation. The existing servo control feed drive system, which uses electromagnetic servo drive, and the developed system, which uses piezoelectric ultrasonic feed drive. The electro discharge processing parameters, including current level, the on-off time and the duty cycle of the machining pulse were the main processing parameters of this investigation. The electron microscopic micro examination into the machined and textured samples showed that: piezoelectric ultrasonic feed drive showed a clear improvement in the quality of surface finish of the machined samples, due to the fast dynamic time response of the developed drive. This was accompanied with a notable reduction in the arcing and short-circuiting teething phenomena. This was verified by assessing the electrode movements, the variations in the inter electrode gap voltage, current and feedback control signals.

Commentary by Dr. Valentin Fuster
2012;():305-308. doi:10.1115/IMECE2012-87414.

Mobile Harbor (MH) recently proposed by KAIST is a novel maritime cargo transfer system that can go out to a container ship anchored in the deep sea and handle containers directly at sea with the aid of the MH crane. Since this system operates under the open sea condition, the MH crane should be newly designed to support inertia load and wind force as well as its self-weight. Wave-induced motions of MH such as rolling, pitching, and heaving generates a significant amount of inertia load, which is ignored in the design of conventional cargo cranes installed on the stable ground. Wind force is also critical to consider a higher level of wind velocity in the open sea. In addition to structural rigidity, mass minimization is important in the design because it generally reduces overturning moment and therefore enhances ship stability. In this paper, we applied topology optimization to the stage of conceptual design for the MH crane, considering all the aforementioned features. We systematically obtained a design candidate through computational framework.

Commentary by Dr. Valentin Fuster
2012;():309-318. doi:10.1115/IMECE2012-87941.

In today’s manufacturing world, system integration often necessitates composing systems of technology that are not designed to interoperate with each other. This inherent incompatibility results in redundant, non–value added work that is required for information to be properly transferred and processed in order for the total system to function properly. As a result, current approaches to systems integration tend to be complicated, costly, time–consuming, and error–prone. In the automotive industry, this integration predicament is found most dramatically in vehicle assembly systems, which are built from a collection of different, incompatible, and multi–vendor “silo” subsystems. This paper will investigate the problems associated with integration of vehicle assembly systems and propose a standard information and communication model to address the integration problems due to incompatible data models. Benefits to the standard information and communication model, including better integration, improvements to the efficiency of the existing vehicle assembly operations, and additional capabilities to increase productivity, is discussed.

Commentary by Dr. Valentin Fuster

Design, Materials, and Manufacturing: Design Innovations, Methodologies and Philosophies

2012;():319-324. doi:10.1115/IMECE2012-85623.

This paper presents a new multi-directional blending technique for heterogeneous object modeling. Contrary to earlier studies, this paper introduces material blending through multiple features with different material composition. Firstly, the Voronoi diagram of multiple-target curves is constructed to generate bisector of the geometric domain. Then, metamorphosis from the generator feature to target features is performed in two steps. First, optimum curve matching between target features and enclosing Voronoi cells is obtained. Then, an optimum ruling line alignment and insertion technique between the Voronoi diagram and generator features is developed. Next, multi-directional material composition is mapped based on a set of relations. The proposed methodologies are implemented and illustrative examples are given in this paper.

Topics: Modeling
Commentary by Dr. Valentin Fuster
2012;():325-333. doi:10.1115/IMECE2012-85938.

Numerous virtual and physical prototyping techniques have been developed in the past decades. These techniques are typically used for prototyping of products in the embodiment and detail design phases of the product development process, without taking into consideration the processes associated with products. These processes include sub-processes related to the operation of the products, interactivity of the product developer or the user with the product, and thinking and manipulative control of humans. The main challenge addressed in this paper is how to conceptualize and communicate ideas about products together with all accompanying processes. We have developed a new concept of abstract prototyping (AP), with the intent to enable the ideation and representation of products or systems as real life processes. In this paper, we present application case studies to demonstrate the applicability of this new concept of abstract prototyping. The preliminary results show that this is indeed the case and prove that process-focused abstract prototyping can be a useful new enabler for design communication. One of the major benefits of the proposed method over the competing approaches such as the application of VR solutions is that it provides a low-cost, but yet effective solution for the challenge of taking into consideration how the product will be used in user’s context or scenario at the very early design stage.

Topics: Design
Commentary by Dr. Valentin Fuster
2012;():335-339. doi:10.1115/IMECE2012-86268.

This paper proposes a design strategy for task-based customized manipulators in modular form. The motivation of work lies in the fact that with change in tasks or working environment, the configuration of robot in use may need significant changes. New set of robotic parameters can be designed from scratch or from the existing specifications. The work is an attempt to systematize this requirement of re-designing and development of customized robotic arms.

Topics: Design , Manipulators
Commentary by Dr. Valentin Fuster
2012;():341-346. doi:10.1115/IMECE2012-86410.

Concurrent Engineering (CE) realized faster time to market with great reduction of time, cost and energy. This old version of CE, however, focused its attention to production within an individual industry. It is process-focused.

It is pointed out that if we expand CE from individual industry to a group of industries, greater increase of productivity and reduction of cost can be achieved.

In this new version of industry-focused CE, overlaps will be eliminated and common functions across industries are pursued.

Such seamless engineering will bring us a great reduction of energy consumption and it will contribute a great deal toward the establishment of the green society.

Commentary by Dr. Valentin Fuster
2012;():347-355. doi:10.1115/IMECE2012-87374.

Automated assembly using robots is being gainfully used to enhance the process capabilities in the manufacturing world because of the fact that it is faster, more efficient, precise and cost effective process than any conventional mechanized process. However in assembly operations it is essential to determine the assembly sequence that is feasible, stable and faster so that an economical process can be evolved. Since robotic system is a cost intensive one it is necessary to find out the correct and optimal sequence with the constraints of the process in mind while dealing with assembled products with large number of parts. One of the most critical situations is to detect the best assembly sequence for products having large number of different alternative solutions. In this paper, a new methodology has been developed to find out the best robotic assembly sequence among the feasible robotic sequences. The feasible robotic assembly sequences have been generated based on the assembly constraints and later, the Artificial Immune System (AIS) has been implemented to find out the best assembly sequence.

Commentary by Dr. Valentin Fuster
2012;():357-366. doi:10.1115/IMECE2012-87376.

This paper introduces a framework for enhancing creative thinking in engineering design. As a flexible methodology, the proposed Creative Engineering Design (CED) framework integrates a new concept development tool, the Concept Assessment Taxonomy (CAT), which constitutes the core of the proposed methodology. By combining the procedures of concept generation, evaluation and selection in a single matrix, the CAT aims to systematize and simplify the overall conceptualization process, while delivering design process transparency.

Early trials have shown the effectiveness of the CED framework in offering procedural guidance and a better comprehension of the multifaceted nature of engineering design. It complements well-established textbook-methods in an effort to reduce ad-hoc and trial-and-error approaches, while minimizing decision-making based on intuition and guesswork.

In order to demonstrate its usefulness within a real world context, the proposed methodology is applied to a case study in the field of mechanical design: a new mechanical fuel injection system capable of curbing small engine emissions.

Commentary by Dr. Valentin Fuster
2012;():367-375. doi:10.1115/IMECE2012-87391.

In a scenario of a small and customized production of Electric Vehicles, it is important to have methodologies and tools able to guarantee high flexibility, good quality, and reduced time to market. The optimisation of electric motors and battery design stages is a key factor to achieve the expected results. Specific activities such as design automation, virtual prototyping and simulation are fundamental to obtain high-performance customised solutions. In this context the study of cooling systems for Li-Ion battery packs is one of the most important problems regarding EV and PHEV powertrain design.

The proposed research presents a Knowledge Based methodology to support the cooling design of a battery pack and an analytical tool to evaluate the temperature and heat generation due to electrochemical reactions. All the research project is finalized to a definition of a Knowledge Based System to define a battery layout including engineering knowledge. The current strategies of battery pack design depend on the market size. In particular, the research activity is focalized on customized production of a SME (Small Medium Enterprise).

The main question concerns the estimation of heat generated from electrochemical reactions in a single battery cell. In order to achieve these objectives, a preliminary phase for knowledge acquisition is necessary and a process of formalization has been carried out using the Knowledge Management methods. A first prototype of the Knowledge Based Engineering tool has been developed to determine the optimal cooling condition of a battery pack. The main module is based on an analytical approach which has been formulated to evaluate the average thermal flow generated by a standard LiFePO4 polymeric cell at different values of current and state of charge (SOC). This method can be used for different types of geometry and different chemical compositions. Finally, the proposed approach has been validated by experimental measures and numerical simulations in collaboration with a medium enterprise of electric energy storage systems and light ecological vehicles.

Commentary by Dr. Valentin Fuster
2012;():377-387. doi:10.1115/IMECE2012-87466.

New customer demands and increased legislation drive business-oriented companies into new business models focusing on the entire life cycle of the product. This forces the manufacturing companies into service-oriented solutions as a compliment to the original business areas. Takata [1] postulates that “the goal is no longer to produce products in an efficient way, but rather to provide the functions needed by society while minimizing material and energy consumption”. This new situation affects the product requirements as well as product development process (PD). When focusing on the entire product life cycle, product aspects such as maintenance and repair will receive more attention since the companies will be responsible for them. In the product development process of today, especially in the automotive industry, maintenance and repair aspects (repair and maintenance methods and manuals, for example) are currently taken care of when the product is more or less fully developed. Maintenance and repair requirements are difficult to quantify in terms of core product properties (for vehicles, cost, CO2 emissions, weight, and so on). This leads to difficulties in equally considering maintenance and repair requirements while balancing vast amounts of product requirements. This paper focuses on a comparison and discussion of existing design guidelines affecting the structure and organization of parts in an assembled consumer product, such as Design for Assembly (DFA), Design for Maintenance (DFMa), Design for Service (DFS) and Design for Disassembly (DFD) methods. A tool for evaluation and analyzing product architecture as well as assemblability and maintainability is proposed.

Commentary by Dr. Valentin Fuster
2012;():389-396. doi:10.1115/IMECE2012-87912.

A methodology for designing polymeric service components for resistance to creep rupture is presented. One of the major difficulties encountered when designing service components that must carry loads for extended periods of time, particularly at elevated temperatures, is the prevention of failures caused by creep rupture. Creep rupture typically occurs at stresses well below the static or quasi static failure stresses commonly used to evaluate the safety of the design. A predictive method is therefore required to guard against such failures.

A Delrin 100 polymer is studied and its creep and creep rupture characteristics at temperatures ranging from 23°C to 85°C are determined. These properties are then used to formulate viscous creep and creep rupture models for use in the commercially available ABAQUS finite element program. The creep material model uses standardized creep test data, and the creep rupture model utilizes an element failure criteria used to predict the time to failure under various stress and temperature conditions. These material models are verified experimentally by performing creep and creep rupture tests at elevated temperatures, and reasonable agreement is seen. An axisymmetric finite element model of a typical service component used in a construction hand tool is then developed using the creep and creep rupture models developed for use in ABAQUS. Creep rupture is predicted over a range of loads and temperatures which are expected in service. Two creep rupture test fixtures are then designed for testing of the service component studied using ABAQUS. These fixtures are used to perform testing of two components simultaneously, and are capable of being loaded into an oven together to allow testing at elevated temperatures to be performed. The prediction of the time to creep rupture under actual service conditions computed by ABAQUS shows reasonable agreement with the component testing.

A methodology for designing components for resistance to creep rupture failures is then developed which focuses on the determination of maximum allowable stresses for a given set of life and loading conditions. The methodology described in this report is validated experimentally by modifying the geometry of the service component to increase the maximum stress to a level which results in a creep rupture failure as predicted by ABAQUS. The component is tested at an elevated temperature and failure at a time near that predicted in the finite element analysis is seen. It is concluded that the utilization of this design methodology can increase service life at the temperatures and load levels seen in service.

Commentary by Dr. Valentin Fuster
2012;():397-404. doi:10.1115/IMECE2012-88012.

Flexible hoses and cables are vital components used in a variety of artifacts, including complex products such as automobiles. When designing a vehicle, it is important to know the shape that a flexible component will take between its two endpoints. Incorrect information regarding