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ASME Conference Presenter Attendance Policy and Archival Proceedings

2014;():V001T00A001. doi:10.1115/ESDA2014-NS1.
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This online compilation of papers from the ASME 2014 12th Biennial Conference on Engineering Systems Design and Analysis (ESDA2014) 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to ASME’s conference presenter attendance policy, if a paper is not presented at the Conference, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.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

Applied Mechanics

2014;():V001T01A001. doi:10.1115/ESDA2014-20062.

In this study we discuss the effect of the loading rate on the distribution of stresses in heavy truck chassis. Stress values on the critical components have been compared with respect to the loading rate under same load magnitude. The results show that loading rate is an important parameter in engineering; using higher loading rates leads to higher fluctuations in the predicted stresses. Our investigation is purely numerical and is based on the commercial finite element software Abaqus / Explicit.

Commentary by Dr. Valentin Fuster
2014;():V001T01A002. doi:10.1115/ESDA2014-20091.

This study addresses in-plane thermal residual stresses in two-dimensional functionally graded plates under a constant in-plane heat flux. The plate material properties vary with a power law along two in-plane directions not through the plate thickness. The transient heat conduction and Elasticity’s Navier equations describing the two-dimensional thermo-elastic problem were discretized using the finite-difference method, and the set of linear equations was solved using the pseudo singular value method. The in-plane transient distributions of temperature, displacement, stress and strain components were determined, and the two-dimensional exponents and directions of compositional gradient were investigated in terms of their effects on the stress and strain distributions in both plates. The exponent and direction of the compositional gradient affected the peak in-plane strain and stress levels; therefore, the stress and strain distributions can be relieved by arranging the exponent and directions of the compositional gradient.

Commentary by Dr. Valentin Fuster
2014;():V001T01A003. doi:10.1115/ESDA2014-20123.

In Hypo-elastic constitutive models an objective rate of the Cauchy stress tensor is expressed in terms of the current state of the stress and the deformation rate tensor D in a way that the dependency on the latter is a homogeneously linear one. In this work, a type of grade-one hypo-elastic models (i.e. models with linear dependency of the hypo-elasticity tensor on the stress) is considered for isotropic materials based on the objective corotational rates of stress. A positive real parameter denoted by n is involved in the considered type. Different values can be selected for this parameter, each selection leads to a specific model within the class of grade-one hypo-elasticity. The spin of the associated corotational rate is also dependent on the parameter n. In the special case of n=0, the corresponding hypo-elastic model reduces to a grade-zero one with the logarithmic rate of stress; noting that this rate is a corotational rate associated with the logarithmic spin tensor. Moreover, by choosing n=2, the model reduces to a grade-one hypo-elastic model with the Jaumann rate, i.e. the corotational rate associated with the vorticity spin tensor. As case studies, the simple shear problem is investigated with utilizing the considered type of hypo-elastic models with various values for parameter n, and the curves for the stress-shear response are depicted.

Commentary by Dr. Valentin Fuster
2014;():V001T01A004. doi:10.1115/ESDA2014-20285.

Friction Stir Welding (FSW) is a welding technique which since its invention in 1991 is of great interest to the industry for its many advantages. Despite being widely used, its physical foundations and its relation to the technological parameters of the process are not known in detail. Numerical simulations are a powerful tool to achieve a greater understanding of the physics of the problem. Although several approaches can be found in the literature for FSW, all of them present different limitations that restrict their applicability to the industry. This paper presents a new solution strategy that combines a meshless method, the Natural Element Method (NEM), with a solution separated representation making use of the Proper Generalized Decomposition (PGD), for creating a new powerful updated-Lagrangian method for addressing the 3D model while maintaining a 2D computational complexity.

Commentary by Dr. Valentin Fuster
2014;():V001T01A005. doi:10.1115/ESDA2014-20347.

Finite element method modeling for flexible coupling of gas turbine compressor package installed in one of PT. Pertamina Hulu Energi Offshore North West Java (PHE ONWJ) facility has been completed. The model delivered result which is in acceptable level of accuracy as compared to manufacturer operating guideline as well as follows in general to guidance of API 671 widely used as industrial code and standard for coupling.

The scope of modeling is including the static and dynamic analysis for both perfectly aligned (used as base reference) and for misaligned condition. The scope covers as well the cyclic stresses which in turns determining the disc pack life time. The major challenge on the modeling is mainly to vary the degree of misalignment and how to distribute the additional load to the flexible part of the coupling causing deformation of disc pack.

The static analysis modeling reveals that the stresses are still below the yield point when aligned perfectly even in high vibration situation, but when it reaches up to 0.1 degree of misalignment with maximum torque the Von-Misses stress has exceeded the yield. The dynamic analysis shows that for similar 0.1 degree the fatigue factor of safety also has exceeded API 671 requirement.

Following the actual coupling failure events, the model has successfully indicated the location of highest stress correlated to crack initiation as compared to actual cracks found in existing discs specimen. The model has been validated as well with the result of material analysis of the damaged flexible discs showing that the failure occurred due to over misalignment.

In addition to manufacturer manual description, the model is capable to recommend maximum angular misalignment that need to be monitored during compressor operation and provide basis to calculate safety factor to comply API 671 guideline.

As oil and gas exploration and production company which focus on possible highest energy efficiency of its operating platforms — which all is located offshore, the work leads a way in integrity management of turbo-machinery equipment in order to maximize running time and minimize production shutdown.

Commentary by Dr. Valentin Fuster
2014;():V001T01A006. doi:10.1115/ESDA2014-20363.

This work presents a closed form investigation on the effect of temperature gradient on the buckling resistance of functionally graded material (FGM) shallow arches. The constituents are assumed to vary smoothly through the thickness of the arch according to the power law distribution and they are assumed to be temperature dependent. The arches subjected to the both uniform distributed radial load and central concentrated load and both boundary supports are supposed to be pinned. The temperature field is approximated by one-dimensional linear gradient through the thickness of the arch and the displacement field approximated by classical arches model. Also, Donnell type kinematics is utilized to extract the suitable strain-displacement relations for shallow arches. Adjacent equilibrium criterion is used to buckling analysis, and, critical bifurcation load is obtain in the complete presence of pre-buckling deformations. Results discloses the usefulness of using the FGM shallow arches in thermal environment because the temperature gradient enhances the buckling resistance of these structures when they are subjected to a lateral mechanical load.

Commentary by Dr. Valentin Fuster
2014;():V001T01A007. doi:10.1115/ESDA2014-20365.

The aim of this paper is to investigate the stress triaxiality effect on the yield stress for the high density polyethylene (hdpe). An experimental protocol has been established to get a wide range of stress triaxialities (negative and positive). Tensile tests, uniaxial compression and simple shear were performed on specimens with different geometries: notched round bar specimens with different curvature radii, cylindrical specimens and parallelepiped specimens respectively. Biaxial tests (combinations of tensile/compressive and shear loading) are also achieved on butterfly-shaped specimens using an Arcan apparatus in order to expand the stress triaxialities. The experimental results demonstrate that the yield stress depends on the stress triaxiality which is due to the hydrostatic stress influence.

Topics: Density , Stress
Commentary by Dr. Valentin Fuster
2014;():V001T01A008. doi:10.1115/ESDA2014-20372.

In this paper, we investigate the computational efficiency of explicit and implicit integration schemes for hyperelastic-plastic combined hardening plasticity and examine the influence on the simulated springback in sheet metal forming. Due to the deviatoric character of the evolution equations, the finite strain combined hardening model discussed here is integrated by means of the exponential map algorithm in order to fulfil plastic incompressibility. We focus here on different possibilities of evaluating the exponential tensor functions of the material model. One option is to use the spectral decomposition to evaluate the exponential tensor functions in closed form. Alternatively, the latter functions can be evaluated by Taylor series expansion. Furthermore, we examine the potential of an explicit formulation of elasto-plasticity with combined hardening regarding accuracy and efficiency. The material model equations have been implemented as user material subroutines UMAT and VUMAT for use in the commercial solvers ABAQUS/Standard and ABAQUS/Explicit, respectively. The numerical models are applied to the finite element simulation of draw bending, where the forming step is simulated both in implicit and explicit manner, whereas the ensuing springback step is carried out only implicitly.

Topics: Hardening
Commentary by Dr. Valentin Fuster
2014;():V001T01A009. doi:10.1115/ESDA2014-20406.

Vibration of a solid circular plate subjected to rapid surface heating is analyzed in this research. Properties of the plate are all temperature and position dependent. Plate is modeled using the first order shear deformation theory. To account for the large deformations, the von Kármán type of geometrical non-linearity is taken into account. Plate is subjected to surface heating at both top and bottom surfaces. Time dependent one-dimensional heat conduction equation is solved via an iterative finite difference scheme and thermal force and thermal moment resultants are evaluated at each time step. Non-linear motion equations of the plate are established with the aid of Hamilton’s principle and the generalized Ritz method. Solution of such equations is obtained employing a hybrid Newton-Raphson-Newmark method. It is shown that thermally induced vibrations exist for the sufficiently thin FGM plate.

Commentary by Dr. Valentin Fuster
2014;():V001T01A010. doi:10.1115/ESDA2014-20419.

In this paper an analysis of Friction Stir Spot Welds (FSSW), applied to lap joint aluminum alloy is presented. The analyses regards the structural behavior of FSSW joints in order to assess the failure mode and its dependence on mechanical properties distribution of the sheets material and, consequently, on process parameters.

FSSW joint is analyzed by means of a complex 3D FE model, which allows to evaluate, in a parametric manner, the multifaceted internal geometry of the joint and the actual distribution of material mechanical characteristics after welding. Experimental tests allowed to verify the results and to calibrate the material characteristics in the FE model.

Commentary by Dr. Valentin Fuster
2014;():V001T01A011. doi:10.1115/ESDA2014-20608.

The Schwarz alternating method, along with Muskhelishvili’s complex potential method, is used to calculate the stresses around non-intersecting circular holes in an infinite isotropic plate subjected to in-plane loads at infinity. The holes may have any size and may be disposed in any manner in the plate, and the loading may be in any direction.

Complex Fourier series, whose coefficients are calculated using numerical integration, are incorporated within a Mathematica program for the determination of the tangential stress around any of the holes. The stress values obtained are then compared to published results in the literature and to results obtained using the finite element method.

It is found that part of the results generated by the authors do not agree with some of the published ones, specifically, those pertaining to the locations and magnitudes of certain maximum stresses occurring around the contour of holes in a plate containing two holes at close proximity to each other. This is despite the fact that the results from the present authors’ procedure have been verified several times by finite element calculations.

The object of this paper is to present and discuss the results calculated using the authors’ method and to underline the discrepancy mentioned above.

Topics: Stress
Commentary by Dr. Valentin Fuster
2014;():V001T01A012. doi:10.1115/ESDA2014-20633.

The theoretical analysis of thrust-induced delamination in hemispherical drilling composite materials was investigated in this study. The theoretical analysis indicated that the thrust force of hemispherical drill at drill and delamination ratio (s) about 0.8 has a significant effect on prevention of delamination damage in drilling composite materials. The maximum thrust force of hemispherical drill at α = 2, however, was about 36% of that of twist drill. In other words, hemispherical drill has a correspondence with lower bearing stresses on drilling-induced delamination, which is liable to cause separation of plies at the exit as the interlaminar bonding yields.

Commentary by Dr. Valentin Fuster

Automotive Systems

2014;():V001T02A001. doi:10.1115/ESDA2014-20002.

Ventilation is part of the acceptable indoor air quality and thermal comfort problem. Carbon monoxide (CO) is a highly toxic gas that’s emitted from cars in vehicular spaces. A new strategy of ventilation called periodic supply exhaust strategy is used. The main advantage of PRESEV strategy is reducing air flow rate requirement and also achieve averaged CO ppm rise according to standards. With the PRESEV strategy a ventilation flow rate 27% of that required by conventional piston or mixed ventilation strategies could achieve the same maximum hourly averaged local CO ppm rise. This paper aims at applying the PRESEV strategy throughout different cases and check effectiveness on these cases.

Commentary by Dr. Valentin Fuster
2014;():V001T02A002. doi:10.1115/ESDA2014-20035.

In order to have an optimized NVH design concept, the design engineers must exchange during the development a lot of attributes that together defines the new engine NVH performance. Moreover, each engine NVH system performance is dependent of many variables. In this respect, 6-Sigma methodology (DMAIC and DCOV) is an excellent tool to support engineers to evaluate systems variables and achieve the required performance.

Engine mount brackets’ vibrations have high priority for the NVH performance of the powertrain. Effects of major components on the engine mount vibrations come up as a major topic whenever an error state takes place and improvement is required. This study aims to identify the effect of engine block, ladderframe, head and transmission stiffness and mass properties on 2EO acceleration levels of the 4 cylinder engine power train. Dynamic analysis will be performed under the kinematic engine loadings. There are 2 steps for identifying the objective. The first step is to eliminate the factors which has not significant main and cross effect on engine mount vibrations.

Full factorial DOE runs with two levels are performed for this purpose. Hyperstudy tool is used for the DOE design, simulation automation and post processing. After defining the effective factors, 256 Latin Hypercube DOE runs are performed to obtain response surfaces and meta–model. DOE runs are done in Hyperstudy, results are exported to enCORE and transfer functions are calculated by Kriging method.

According to the results, a proposed course of action for engine mounts’ accelerations DOE study is prepared and a methodology for this course is executed.

Commentary by Dr. Valentin Fuster
2014;():V001T02A003. doi:10.1115/ESDA2014-20037.

A complex system is composed of many interacting components, but the behavior of the system as a whole can be quite different from that of the individual components. An automobile is an example of a common mechanical system composed of a large number of individual components that are mechanically connected in some way and hence transmit vibrations to each other. This paper proposes a variety of inter-related analytical tools for the study of experimental data from such systems. In this work, experimental results of accelerometer data acquired at two locations in the automobile for two different kinds of tests are analyzed. One test is the response to impact on a stationary vehicle, and the other is the road-response to the vehicle being driven on a flat road at different speeds. Signals were processed via Fourier and wavelet transforms, cross-correlation coefficients were computed, and Hilbert transforms and Kuramoto order parameters were determined. A new parameter representing synchronization deficit is introduced. There is indeed some degree of synchronization that can be quantified between the accelerations measured at these two locations in the vehicle.

Commentary by Dr. Valentin Fuster
2014;():V001T02A004. doi:10.1115/ESDA2014-20067.

This study investigates the effect of combustion phase (premixed and diffusion phases) duration on the emissions emitted from a high speed direct injection (HSDI) diesel engine fueled with neat (100%) rapeseed methyl ester (RME) and run at a constant speed (1500 rpm) with single injection strategy at constant fuel injection pressure (800 bar) and varying fuel injection timings (−12,−9,−6,−3,0) ATDC, for two loads (2.5 and 5 bars) BMEP. The obtained results were compared with those obtained when the engine run at the same conditions but with ultra-low sulfur diesel fuel (ULSD). In-cylinder pressure was measured and analyzed using (LABVIWE) program. calculation program specially written in (MATLAB) software was used to extract the apparent heat release rate, the ignition delay, combustion duration and specify the amount of heat released during the premixed and diffusion combustion phases (premixed burn fraction PMBF) and (diffusion burn fraction DBF). Emission measurements included; NOx, CO, THC, CO2 and smoke number (SN). The results showed that at high load, RME generate higher NOx, CO and THC. Measurements and calculations indicated that ignition delay of RME was shorter than that of ULSD, which means less PMBF. This conflicting effect is probably due to the advanced start of combustion (SOC) leading to higher combustion temperature inside the combustion chamber and there will be less time available to complete the combustion. The emission results at low load showed that NOx and CO, generated by RME were less than those generated by USLD. USLD produced soot more than RME at high load and less at low load.

Commentary by Dr. Valentin Fuster
2014;():V001T02A005. doi:10.1115/ESDA2014-20120.

The work addresses the optimization of the steering and roll systems of an innovative four-wheeled tilting vehicle, which is currently being built at the University of Padova. The vehicle is a combination of traditional two and four-wheeled forms, with the driver operating a bike handlebar to steer, and throttle and brake inputs to control speed. Two pedals control the roll movement, while the gearshifts are made automatically. The steering system consists of a handlebar, column, pinion, rack and track-rods to the wheels. In the resulting spatial mechanism, roll and steer motions of the wheels are coupled. The kinematic optimization presented in this paper, aims at minimizing undesired roll to steer behaviour, and provides appropriate outer/inner wheel steer angles. The natural coordinate approach is employed to efficiently simulate and optimize the mechanism.

Commentary by Dr. Valentin Fuster
2014;():V001T02A006. doi:10.1115/ESDA2014-20157.

Suppressing or limiting the differential action of the differential mechanism is the mostly adopted technique to avoid the skidding of a driving wheel of a vehicle riding on a poorly adherent surface. The devices carrying out this function unbalance the traction force distribution in the differential, generating a yaw torque acting on the vehicle as a secondary effect. If the unbalancing action is electronically controlled, this yaw torque can be used to affect the attitude of car as a torque vectoring technique.

In this paper, a purpose built differential is presented and its technical features are highlighted, including the electrohydraulic actuation. Moreover, its torque vectoring capabilities are discussed, basing on the numerical simulation campaign performed deploying this device in a 7 DOFs model of a race car with low ground effect.

The results of these simulations are compared with the behavior of the same vehicle equipped with a common passive locking differential, to show that the proposed one and its control logic (which relies on only measurable inputs) are able of improving the handling of the vehicle, in terms of both vehicle stability and linearity with the driver’s inputs. Therefore, this system could be considered as a completion of the common ESC (“Electronic Stability Control) systems to control the vehicle attitude when using the brake system is an inefficient solution.

Commentary by Dr. Valentin Fuster
2014;():V001T02A007. doi:10.1115/ESDA2014-20159.

Passive safety systems such as airbags, seat belts, and interior structural design of the automobile play a significant role in injury prevention of the occupant during collisions. Important design and operation parameters of the passive safety systems such as airbag firing times and steering wheel position as an interior design attribute potentially affect the dynamics of the occupant during impact and determine the amount of mitigation of a possible injury. This research aims to contribute towards improving passive safety systems in automobile design for mitigation of injuries by optimising the features and parameters of various subsystems such as driver’s airbag and steering wheel. Two separate computational models, a 5th percentile female and a 50th percentile male, comprising of a typical automobile interior with passive safety systems are constructed in the specialised impact simulation software MADYMO. Two different crash pulses of 30 kph and 48 kph are applied to the computational human body models in full-frontal crashes. Passive safety system parameters; in particular, airbag firing times and steering wheel column angles, are varied to investigate their effects on the head, neck and upper torso through injury criteria. Injury criteria predictions are employed in optimisation algorithms to figure out the best combinations for passive safety system parameters in order to mitigate possible injuries for all drivers.

Commentary by Dr. Valentin Fuster
2014;():V001T02A008. doi:10.1115/ESDA2014-20217.

The environmental concerns officially aroused in 1970s made the control of the engine emissions a major issue for the automotive industry. The corresponding reduction in fuel consumption has become a challenge so as to meet the current and future emission legislations.

Given the increasing interest retained by the optimal use of a Variable Valve Actuation (VVA) technology, the present paper investigates into the potentials of combining the VVA solution to CNG fuelling. Experiments and simulations were carried out on a heavy duty 6-cylinders CNG engine equipped with a turbocharger displaying a twin-entry waste-gate-controlled turbine. The analysis aimed at exploring the potentials of the Early Intake Valve Closure (EIVC) mode and to identify advanced solutions for the combustion management as well as for the turbo-matching. The engine model was developed within the GT-Power environment and was finely tuned to reproduce the experimental readings under steady state operations. The 0D-1D model was hence run to reproduce the engine operating conditions at different speeds and loads and to highlight the effect of the VVA on the engine performance as well as on the fuel consumption and engine emissions. Pumping losses proved to reduce to a great extent, thus decreasing the brake specific fuel consumption (BSFC) with respect to the throttled engine. The exhaust temperature at the turbine inlet was kept to an almost constant value and minor variations were allowed. This was meant to avoid an excessive worsening in the TWC working conditions, as well as deterioration in the turbocharger performance during load transients. The numerical results also proved that full load torque increases can be achieved by reducing the spark advance so that a higher enthalpy is delivered to the turbocharger. Similar torque levels were also obtained by means of Early Intake Valve Closing strategy. For the latter case, negligible penalties in the fuel consumption were detected. Moreover, for a given combustion phasing, the IVC angle directly controls the mass-flow rate and thus the torque. On the other hand, a slight dependence on the combustion phasing can be detected at part load. Finally, the simulations assessed for almost constant fuel consumption for a wide range of IVC and SA values.

Specific attention was also paid to the turbocharger group functioning and to its correct matching to the engine working point. The simulations showed that the working point on the compressor map can be optimized by properly setting the spark advance (SA) as referred to the adopted intake-valve closing angle. It is anyhow worth observing that the engine high loads set a constraint deriving from the need to meet the limits on the peak firing pressure (PFP), thus limiting the possibility to optimize the working point once the turbo-matching is defined.

Topics: Engines , Valves
Commentary by Dr. Valentin Fuster
2014;():V001T02A009. doi:10.1115/ESDA2014-20240.

This paper presents a disc type of electromagnetic circuit for designing of an electromagnetic valve actuator (EVA). The static and the dynamic equations of the system are derived and their numerical solutions are obtained with MATLAB/Simulink programs. A prototype of the EVA was built and some preliminary tests were carried out on them for static and dynamic tests. The effect of holding current is obtained on the dynamic behavior and energy consumption of the system.

Commentary by Dr. Valentin Fuster
2014;():V001T02A010. doi:10.1115/ESDA2014-20341.

The development of compact and efficient hybrid electric vehicle powertrains for low initial and on-going costs requires consideration of numerous, often competing factors. Appropriately designing and sizing these powertrains requires the consideration of requirements for vehicle range and performance, considered directly through the sizing of motors and engines, and indirectly through minimization of vehicle mass whilst being constrained by total stored energy in the vehicle, against the impact on vehicle emissions and on purchase and ongoing operational costs. In addition to these considerations the actual driver use will strongly influence the energy consumed and vehicle emissions. It therefore becomes beneficial to provide flexibility in hybrid vehicle configuration design to enable the minimization of vehicle emissions and ongoing vehicle costs.

The purpose of this paper is to study the various alternative vehicle powertrain configurations for application to small scale hybridization demands, such as scooters or motorcycles. Powertrain configurations studied in this paper include plug-in hybrid electric (PHEV), battery hybrid electric (BHEV), and a pure electric vehicle (PEV). To design and size each of the configurations a statistical approach is taken, power and load demands are studied and utilized to size powertrain components. Results are extended to size vehicle energy storage for electric only range of 25, 50 and 100 km, and total vehicle range of 100 km for the BHEV and 200 km for the PHEV. Based on the results developed from the analysis mathematical models of each of the powertrain configurations are then developed in Matlab/Simulink and numerical studies of vehicle energy consumption in comparison to range are conducted. Outcomes of these simulations are compared to an operating cost based analysis of the suggested powertrains; the benefits and limitations of each design are considered in detail.

Topics: Design
Commentary by Dr. Valentin Fuster
2014;():V001T02A011. doi:10.1115/ESDA2014-20364.

This paper presents an activity concerning a theoretical/experimental analysis of a new measurement system of the chain strength functional for the control of the electrically assisted bicycles. Such systems are characterized by a driving torque due to the contribution of an electric motor and of the rider. The electrical assistance is commonly regulated taking into account informations such as chain ring rotation, bicycle speed and/or the torque given by the rider. As a consequence, suitable measurements have to be made on board in order to handle the assistance performances and to improve drivability.

Commentary by Dr. Valentin Fuster
2014;():V001T02A012. doi:10.1115/ESDA2014-20369.

Engine simulation software has become synonymous with automotive design and component development. An integral part of any engine simulation is the correct modeling of the air flow at the intake. This air flow, which is highly compressible and unsteady, has a first order influence on the trapped air mass inside the cylinder and therefore on the behavior of the engine (torque response and emissions). The non-linear modeling of the air paths at the intake is done using a space-time meshing and by solving the 1D equations with a proper time scheme. Such methods are the bases of today’s engine simulation codes [1]. The main constraint with these methods is the time needed to model complex geometries, whether being the simulation time or the time spent on calibrating the said models with experimental measurements. These complicated geometries become problematic to accurately predict, particularly the charge air cooler (CAC) which is responsible for cooling the air flow on a turbocharged engine.

Another approach is to use frequency domain models to describe the fluctuating pressure and mass flow [2]. Although this approach is simpler, faster in terms of computing time and offers many experimental techniques to characterize complicated geometries; important limitations can appear when it is confronted to the effects of high pressure levels and pulsating mass flow. Furthermore, the models behind such methods are designed to be used in the frequency domain, contrary to an engine simulation that works solely with time domain variables.

In this article, a linear frequency domain model known as a transfer matrix is used. This concept is nothing new in acoustics; however here it was developed by experimentally measuring the transfer matrix [3] for a simple tube on a dedicated bench under conditions similar to those encountered on an engine [4]. The approach is then extended to measure the transfer matrix of a charge air cooler (CAC) on a real engine test bench. The measured discrete transfer matrix, defined in terms of fluctuating pressure and mass flow, is then transformed to a continuous frequency model and coded in Simulink®. The latter is coupled to the non-linear engine simulation software GT-Power®.

The objective is to accurately model the pressure and mass flow of a complicated geometry using experimental measurements and a linear frequency model then to couple the transfer matrix to an engine simulation code, thus replacing the need for a meshed model.

Commentary by Dr. Valentin Fuster
2014;():V001T02A013. doi:10.1115/ESDA2014-20371.

This paper deals with the design and testing of a miniature CVT prototype. The CVT under study is a special toroidal-type, which is able to maintain a quasi-constant power at the output element by automatically changing the transmission ratio function of the torque applied to the output element. The power-transmitting elements of the device have been built by modifying rolling element bearings.

Topics: Modeling , Testing
Commentary by Dr. Valentin Fuster
2014;():V001T02A014. doi:10.1115/ESDA2014-20392.

Although it is well known that the flow entering a turbine of a turbocharger engine is highly unsteady, engine manufacturers prefer to use turbine performance predictions that are based on steady-state performance maps, which inherently lead to inaccuracies in the turbine’s behavior and mismatches between turbocharger turbines and engines. The reason for this preference is due to the turbocharger turbine design software that are generally available to engine manufacturers being based on and compatible with steady-state performance maps and this fact led researchers to investigate how the inaccuracies of this steady-state treatment of the turbine can be alleviated.

To this effect, this paper investigates how modelling techniques on Ricardo Wave, a 1D gas dynamics engine simulation software, gives rise to more accurate turbine swallowing curve predictions using steady-state maps. In particular, the turbine being investigated is that of Szymko [1], which is a twin nozzleless mixed-flow turbine that is being powered by a 10 litre, 6 cylinder 4 stroke diesel engine with an operating range from 800–2000 RPM for which 800, 1200 and 1600 engine RPM relate to 40, 60 and 80Hz exhaust gas pulse frequencies at the turbine.

The main investigation in this paper is to demonstrate the capability of the engine simulation software to deal with unsteady flows and specifically to show the significant effect of accounting for the volute design in the single turbine wheel entry model. The data obtained in this investigation were compared with those of Szymko [1], which offered a validated set of data to compare against.

Commentary by Dr. Valentin Fuster
2014;():V001T02A015. doi:10.1115/ESDA2014-20413.

For dynamic car simulators, it is obvious that the longitudinal motion cannot be fully reproduced, the possibility to simulate longitudinal motions being generally reduced to less than 1m. In our case, a four post shaker is intended to be built as dynamic car simulator. Each post shaker, one under each car wheel, is aimed to generate mainly vertical vibrations and lateral motion. Since the displacements/motion in the longitudinal direction can only be partially reproduced, our problem was how to compensate the impossibility of fully reproducing the longitudinal motion by at least taking into account the influence of the longitudinal motion on the vertical vibrations.

In this paper a simplified 4 DOF “bicycle” model is used for vertical dynamics, instead of a 7 DOF full car vertical dynamics model, which will be considered in a further study.

On the other hand, the vertical vibrations are different for the same car riding on the same road, but for different acceleration regimes: 1) null acceleration (e.g., 60km/h constant speed); 2) uniform acceleration from 10 to 110 km/h (during 8 seconds), followed by uniform deceleration from 110 to 10 km/h (during another 8 sec), then uniform acceleration from 10 to 60 km/h (during the last 4 sec of the simulation).

In order to reproduce in the dynamic car simulator the vertical vibrations of the above-mentioned longitudinal motion regimes (involving displacements of tens of meters), the following steps are proposed: a) direct dynamics CARSIM computer simulations of the car motion and its interaction with the road; b) inverse dynamics of car vertical model (4 degrees of freedom), using as input the following parameters computed in step a): the vertical displacements and velocities of the sprung mass and of the front and rear wheel centers as well as the pitch angle of the sprung mass and its rate. These inverse dynamics computer simulations are performed using an in-house Matlab software programming only the 4-DOF vertical car/road interaction (2D “bicycle” model in the pitch plane, no roll motion considered), without considering any longitudinal motion.

The output of these inverse dynamics computer simulations, using the in-house Matlab software, is the “modified/distorted road profile”. Thus, the modifications brought to the real road profile are aimed to compensate the lack of the longitudinal degree of freedom in the dynamic car simulator, in order to reproduce the vertical vibrations of the above-mentioned longitudinal motion regimes (so that to encounter the same car vertical displacements and accelerations for the in-house Matlab simulation, as for the CARSIM simulation).

Results are presented in order to show how the real road profile is modified/distorted in order to cope with this impossibility to simulate the road profile in dynamic car simulators, without huge costs.

Topics: Vibration
Commentary by Dr. Valentin Fuster
2014;():V001T02A016. doi:10.1115/ESDA2014-20438.

This paper describes the on-road test program that was used for a performance study and environmental analysis of an electrically assisted bicycle in the urban area of Naples. For this purpose, the vehicle was tested on different test tracks, cycling over 2000 km, and then making a general assessment about the driving behavior under real conditions.

Based on the findings obtained during the different test samples, an appraisal of the electric traction offered by this bicycle on the driving comfort was evaluated for different conditions: electrical assistance at start, on a flat road and when riding uphill. The power requirements in different typical riding situations were also calculated: these results were estimated by experimental kinematic parameters that describe the driving dynamics collected during the real-life applications. An environmental analysis was made and also put against the environmental impact of a thermal moped.

Commentary by Dr. Valentin Fuster
2014;():V001T02A017. doi:10.1115/ESDA2014-20477.

Present work is aimed at studying into detail mixture formation and combustion in a gasoline direct injection (GDI) engine working under stoichiometric mixture conditions. The study is performed both numerically and experimentally. From the experimental side, the engine, optically accessible, is characterized by collecting, for various injection strategies, in-cylinder pressure cycles and digital images. From the numerical side, a 3D engine model is developed, that includes proper sub-models for the spray dynamics and the spray-wall interaction. This last phenomenon is studied into detail by resorting to a preliminary 3D simulation of the spray impingement realized in a proper experiment, where the engine injector is mounted at a certain distance from a cold or hot wall.

An interesting comparison between numerical and experimental images of the in-cylinder spray dynamics is presented, that also allows individuating the difference in the wallfilm deposition under various injection strategies. This opens the way to understand the difference in the combustion development arising as injection is anticipated or retarded in the engine working cycle.

Commentary by Dr. Valentin Fuster
2014;():V001T02A018. doi:10.1115/ESDA2014-20480.

The purpose of this study is to design brushless permanent magnet DC motors for electric vehicles based on a pole-changing method. By generating a pulse when changing the number of poles, magnetization of magnets can be changed appropriately and the principle of pole-changing motors can be applied to permanent magnet machines. This kind of machine not only retains the feature of permanent magnet machines in efficiency, but also acquires wide speed range. In this study, a pole-changing method using common windings is proposed and performance of brushless permanent magnet DC pole-changing motors is investigated. According to T-N curves, the proposed brushless permanent magnet pole-changing motor yields larger starting torque and wider speed range than motors with a fixed number of poles.

Commentary by Dr. Valentin Fuster
2014;():V001T02A019. doi:10.1115/ESDA2014-20513.

Computational occupant modelling has an effective role to play in investigating road safety. Realistic representation of occupants is very important to make investigations in virtual environment. Pregnant occupant modelling can help investigating safety for unborn occupants (fetuses) however, existing pregnant occupant models are not very realistic. Most do not anthropometrically represent pregnant women and do not include a fetus model.

‘Expecting’, a computational pregnant occupant model, developed with a view to simulate the dynamic response to crash impacts is briefly explained in this paper. The model is validated through rigid bar impacts and belt loading tests and used to simulate a wide range of impacts. ‘Expecting’, possess the anthropometric properties of a 5th percentile female at around the 38th week of pregnancy. The model is complete with a finite element uterus and a realistic multibody fetus which is a novel feature in models of this kind.

In this paper, the effect of further developments to ‘Expecting’, by incorporating a finite element fetus head model is investigated. Further detailed anatomic geometry is used to generate deformable fetus head model. The model is used to simulate a range of frontal impacts with seatbelt and airbag, as well as no restraint cases. The strains developed in the utero-placental interface are used as the main criteria for fetus safety. The effect of incorporating a finite element fetus head in the pregnant occupant model is discussed.

Topics: Safety , Vehicles
Commentary by Dr. Valentin Fuster
2014;():V001T02A020. doi:10.1115/ESDA2014-20545.

Very often processes associated with rotating machinery entail two general types of random processes: (i) quasi-periodic processes linked directly to the machine rotational frequency (including harmonics and sub-harmonics), and (ii) regular processes such as those associated with random vibration of machinery elements. Variability of the rotational frequency and slow-time variability can both be induced by factors such as time-varying external loading and changing thermodynamics (e.g. the influence of road grade and engine temperature on automobiles using cruise control). In this work we incorporate and extended Kalman filter (EKF) model guided by estimates of the family of AR and MV spectral estimates to arrive at a method of decomposing and tracking these two types of processes, along with related parameters (e.g. frequency jitter bandwidth/intensity and the strength, damping and natural frequency of randomly excited narrowband resonances). This work may be viewed in some ways as an extension of the work presented in [1]. Our findings include (i) for the case of constant nominal speed, the EKF estimates of the time-varying frequency, sine and colored noise processes are quite good; whereas the estimate of the time-varying amplitude is not as good, and (ii) in the case of linearly increasing speed (where the colored noise resonance behavior is only excited in that portion of the observation time where the sine frequency is in close proximity), the estimated root mean-squared errors related to both the frequency and the noise increase linearly with the nominal frequency rate of change.

Topics: Machinery , Filtration
Commentary by Dr. Valentin Fuster
2014;():V001T02A021. doi:10.1115/ESDA2014-20599.

Power management systems are one of the most important components in modern hybrid vehicles. They are needed to optimize the operation of the hybrid system components. In this paper, a model for a fuel cell/battery vehicle is developed using PSAT and then tested with four power management control strategies utilizing the driving cycle of Amman city, the capital of Jordan. The main components of the hybrid vehicle are a PEM fuel cell, battery, and a brushless dc motor. PEM fuel cells are popular due to their good start up, high power density, and low operating temperature. The role of the battery in a hybrid system is to boost the system power during start-up and transient events in addition to storing the energy recovered from the braking process. The developed hybrid vehicle model is designed and configured so that it matches the power, acceleration, and maximum speed of a midsized vehicle powered by an internal combustion engine. The proposed control strategies are the thermostat strategy, fuel cell optimized strategy, load following strategy and fuzzy logic strategy. All four control strategies are implemented in simulation utilizing PSAT. The simulation results indicate that the best performance in terms of fuel economy is achieved by the load following control strategy.

Commentary by Dr. Valentin Fuster
2014;():V001T02A022. doi:10.1115/ESDA2014-20600.

A good driving cycle is needed for accurate evaluation of a vehicle’s performance in terms of emission and fuel consumption. Driving cycles obtained for certain cities or countries are not usually applicable to other cities or countries. Therefore, considerable research has been conducted on developing driving cycles for certain cities and regions. In this paper, a driving cycle for a taxi in Amman city, the capital of Jordan, is developed. Significant differences are noted when comparing the Amman driving cycle with other driving cycles. A model of a gasoline powered vehicle is used to conduct a performance comparison in terms of fuel economy and emissions utilizing the developed Amman driving cycle and six other worldwide driving cycles. The developed Amman driving cycle is very useful in obtaining accurate estimation of fuel economy and emissions for vehicles running on Amman roads and will be used in future work to study the performance of hybrid fuel cell/ battery vehicles.

Commentary by Dr. Valentin Fuster

Biomedical Biotechnology Engineering

2014;():V001T03A001. doi:10.1115/ESDA2014-20081.

A new device for hand rehabilitation of stroke patient is presented. Its main innovative features are: lightness, real safety guaranteed by its structural elasticity, smoothness and easiness of movements. The kinematic behavior of the system hand-plus-rehabilitation-device is analyzed. The device applicability is confirmed by positive testing.

Cerebrovascular diseases are the third cause of mortality and the second cause of long term disability in Western countries. The 60% of survived individuals shows a sensitive/motor deficit of one or both hands and must be subjected to a rehabilitative treatment to recover the use of the upper limb.

Recent technologies have facilitated the use of robots as assistive tools to patients, providing safe and highly personalized rehabilitation sessions, thus making therapist contribution to recovery much more intensive and effective.

We propose in this work a wearable glove with an incorporated compliant mechanical transmission over the hand.

The glove is composed by two main modules with well-defined mechanical characteristics. One is the actuator on the upper side of the forearm, close to the wrist (and to the impaired hand) and still separated from it; the other (the transmission) is composed by several elastic transmissions which, moved by the actuator, properly transmit displacements, speed and forces to one or more impaired fingers during a rehabilitation session. While the actuator module has a rigid and defined structure and is fixed to the forearm section of the glove, the “transmission” module has in fact a labile and extended structure as it has to reach all five fingers (one, some, or all might be impaired and in need of rehabilitation) up to their tips and move them in an effective and reliable way.

A kinematical characterization of the compliant transmission is proposed to dimension the actuators and to define the correct commanded motion profile at actuator level.

Commentary by Dr. Valentin Fuster
2014;():V001T03A002. doi:10.1115/ESDA2014-20199.

The present paper deals with the development of a bench for testing different types of lower limb prostheses. Aim of the bench is to test the prosthetic devices considering working conditions as much as possible similar to the real ones with respect to methodologies provided by International Standards. These standards merely identify structural tests whose purpose is just to verify that the prosthesis, or their individual components, are able to ensure adequate strength properties during their use. The only functional test concern just the ankle-foot units. Test methods for the assessment of the functional performances of the whole prostheses are missing. There are no criterions for such tests and no benches. From this the need to build new test machines that, simulating both the stance and the swing phase according to sought gait standards, allow to assess the functional properties of different lower limb prostheses and to make comparison between them. According to this, the purpose of the present work is to assess the feasibility of such a bench, evaluating, by mean of a co-simulation executed considering a Multi-Body model of the bench developed using MSC ADAMS and a model of the control system developed using MATLAB/Simulink, its capability in guaranteeing the sequential replication of movements and loads that distinguish a leg during the execution of the stride. The obtained results demonstrate the feasibility of the machine, encouraging therefore the development of more refined models, considering technological solutions closer to reality.

Topics: Design , Prostheses , Testing
Commentary by Dr. Valentin Fuster
2014;():V001T03A003. doi:10.1115/ESDA2014-20213.

Eggshell (ES) is one of the most common biomaterials in nature. For instance, the ES represents 11% of the total weight of a hen’s egg and it is composed of calcium carbonate, magnesium carbonate, tricalcium phosphate and organic matter. Hen ES are also a major waste product of the food industry worldwide. Recently, ES have been used for many applications such as coating pigments for inkjet printing paper, catalyst for biodiesel synthesis, bio-fillers for polymer composites and matrix lipase immobilization. It is also considered a natural biomaterial with high potential for the synthesis of calcium enriched implants that may be applied in tissue engineering applications, such as bone regeneration. The aim of this research regards the production of poly(ε-caprolactone) (PCL) scaffolds enriched with hen ES powder for bone regeneration applications, using an extrusion-based process called Dual-Bioextruder. The main objective is to investigate the influence of the addition of ES powder on the PCL matrix. For this purpose the structures were characterised regarding morphological and chemical properties. Morphological images of the PCL scaffolds enriched with hen ES, demonstrated the interconnectivity of the pores within the scaffold and revealed that the addition of the ES powder combined with the screw rotation velocity has a large influence on the resulting filament diameter and consequently on the porosity of the scaffolds.

Topics: Bone
Commentary by Dr. Valentin Fuster
2014;():V001T03A004. doi:10.1115/ESDA2014-20223.

Investigating the mechanical behavior of a healthy human ankle shows that it can be simulated by a mechanism composed of simple elements such as spring, and actuator. Hence, appropriate design of this mechanism can be resulted to an artificial ankle that can help amputees properly. Researches show that whatever the biomechanical behavior of artificial ankle is similar to that of natural ankle, it can be used by consuming less energy. Considering biomechanical behavior of normal ankle in a walking gait, required parameters for designing of an artificial ankle composed of springs and electromechanical actuator will be determined. Finally, to verify the suggested model, a prototype will be materialized and tested.

Topics: Design
Commentary by Dr. Valentin Fuster
2014;():V001T03A005. doi:10.1115/ESDA2014-20234.

The presented study is focused on the hemodynamics aspects of thoracic aortic aneurysm and approaches for restoring hemodynamics in the aortic arch. The study includes numerical investigation of the aortic arch hemodynamics of a healthy aorta, aorta with aneurysm, and of two endovascular repairing procedures. The first endovascular repair approach is the total aortic arch hybrid debranching. The second implantation uses chimney graft technique.

The analysis includes the fluid dynamics in the aorta and branching arteries under time-dependent physiological conditions. The results show the effect of aneurysm on blood flow in the descending aorta and in aortic arch side branches. In the aneurysmatic case, the aneurysm provokes a highly disturbed flow and large recirculation regions, especially during diastole. Out of the two endovascular techniques, the hybrid procedure was found preferred from hemodynamics point of view, with less disturbed and recirculating regions.

Although the chimney procedure requires less manufacturing times and cost, it is associated with higher risks rate, and therefore, it is recommended only for emergency cases. This study may shade light on the hemodynamic factors for these complications, and provide insights on ways to improve the procedure.

Commentary by Dr. Valentin Fuster
2014;():V001T03A006. doi:10.1115/ESDA2014-20300.

It is well known that the stent design plays an important role in the outcome of the stenting interventional procedure. Thus, analyzing and comparing the behavior of different types of stent is essential to select the most appropriate stent design to use. Furthermore, assessing the behavior of stent is one of the components of the process in which new biomedical stent devices are designed and approved. Indeed, new stent designs have to be proved to be equivalent to an approved stent to be confirmed from the regulatory agencies. This sets the stage for a series of “stent versus stent” randomized trials designed to show that each newer stent design was not inferior to the prior approved stent. In this paper, finite element method is used to assess the behavior of stents. The objective of this work is to present a numerical alternative for “stent versus stent” complicated clinical studies. Three commercially available stents (the Palmaz–Schatz, Multi–Link and NIR stents) are modeled and their behaviors are compared. According to the findings, the possibility of restenosis is lower for Multi–Link and NIR stents in comparison with Palmaz–Schatz stent which is in good agreement with clinical results.

Commentary by Dr. Valentin Fuster
2014;():V001T03A007. doi:10.1115/ESDA2014-20375.

A new personal device to assist the upper limb capable to be mounted on a wheelchair is being tested. The robot is equipped with three brushless motors powered by four electronic boards appositely designed and communicating via I2C protocol; one board works as master for the other three, which have simpler tasks. Most of the driving software has been developed with Matlab and mainly translated into C++ for memory space and boards’ efficiency matters. The system’s end-effector is connected to the subject’s forearm and can cooperate to the arm motion in several different ways. In order to avoid the overstress of the natural joints no further connections are made to the upper limb. The working volume of the limb connected to the device allows the execution of the trajectories required for most of daily living activities. It is addressed to post stroke rehabilitation and to the self-treatment of other patients with serious deficiency of arm forces, like individuals affected by muscular dystrophy. Some working modes exploit the mechanical impedance control to gently interfere with the residual natural motion capability of the subjects. The very preliminary tests of the prototype fitted on a power wheelchair are encouraging: it is light, not too noisy and easy to move for the subject. The first working mode, with full arm gravity compensation, and the second working mode, with partial compensation, have been implemented and are currently being tested with patients, as well as the mode in which the subject is helped to repeat a stereotyped exercise for self-physiotherapy. Beside the fact the control system must be calibrated on patient characteristics, for these initial tasks the system reveals to be user-friendly. Other working modes require to interpret the patient intention to move the upper limb. For a natural approach it is sufficient to decode the movement intention of the patient and the final position he wants the hand to reach, whilst the rest of the limb can be automatically positioned by the system. Different approaches to solve the problem have been experimentally tested, including the use of a headgear with a brain interface. To present knowledge the best results have been obtained by monitoring the movement of another body segment such as the head. The device designed for the functional recovery of upper limb can furthermore be used to monitor and easily certify the evolution of the patient conditions.

Commentary by Dr. Valentin Fuster
2014;():V001T03A008. doi:10.1115/ESDA2014-20428.

The neck portion of the human femur is the most vulnerable region to attract stress-induced fractures. The loads of the human body act on the hip joint and on the greater trochanter region through abductor muscles. The bone is a natural composite and a good example of functionally graded material (FGM). This study considers a probabilistic finite element approach to assess the critical stresses in the femur under static loads. Material properties assigned to the bone model are linearly elastic, isotropic and orthotropic. Material characterization in terms of bone density is established by Computed Tomography (CT) data. The strength reliability and safety margin are obtained using relevant limit state function. Sensitivity analysis with respect to random parameters provides basis for a possible implant material characterization.

Topics: Reliability , Bone
Commentary by Dr. Valentin Fuster
2014;():V001T03A009. doi:10.1115/ESDA2014-20547.

The implantation of intravascular stent is a kind of coronary angioplasty to restore the blood flow perfusion to the downstream of the heart muscle tissue. Stent implantation is a mechanical procedure, the success of which depends to a good understanding of its mechanical behavior during the deployment. Computational studies may be used to investigate the mechanical behavior of stents and to determine the biomechanical interaction between the stent and the artery in a stenting procedure. The aim of this paper is to investigate the expansion characteristics of a certain stent as it is deployed and implanted in an artery containing a plaque, and try to reach to a model close to a real condition of stent implantation. Unlike most of the models proposed in the literature, all the steps of the deployment of a stent in the stenotic vessel (i.e. pressure increasing, constant load pressure and pressure decreasing) are simulated in this paper to show the behavior of stent in different stages of implantation. Results include stress distribution, radial gain, outer diameter changes, dogboning and foreshortening. According to the findings, the first step of deployment, i.e. pressure increasing, play a main role in the success of stent implantation.

Commentary by Dr. Valentin Fuster
2014;():V001T03A010. doi:10.1115/ESDA2014-20597.

This paper presents a possibility to use Resonant Ultrasound Spectroscopy as nondestructive evaluation method for ceramic elements of prosthesis such as ceramic femoral heads. With this method can be emphasized the incorrect sintering of these elements as well as eventually cracks. If the number of resonance peaks is big enough, the elements of elasticity matrix can be determined, demonstrated by effective measurements on zirconia with different stabilizers cylindrical samples taken into study.

Commentary by Dr. Valentin Fuster

Computational Mechanics

2014;():V001T04A001. doi:10.1115/ESDA2014-20011.

Functionally graded materials (FGMs) are multi-phase inhomogeneous composites, possessing smooth spatial variations in certain physical properties of the constituents. Depending on the types of the constituent materials used in the processing of orthotropic FGMs, the influences of thermal and hygroscopic loadings could be rather significant. This study is directed towards developing a new computational fracture analysis technique for orthotropic FGMs that are under mixed-mode hygrothermal loading. The method is based on the use of the J-integral in conjunction with the asymptotic crack tip displacement fields. Developed computational technique is integrated into a finite element analysis software. Parametric analyses are carried out by considering an inclined edge crack in an orthotropic FGM layer that is subjected to the influence of hygrothermal loading. In order to be able to verify the proposed method, obtained results are compared to those computed via displacement correlation technique (DCT). Comparisons demonstrate that proposed technique leads to numerical results of high accuracy. Further results are provided to illustrate the influences of crack inclination angle and geometry on the temperature and the specific moisture concentration fields; and the modes I and II stress intensity factors.

Commentary by Dr. Valentin Fuster
2014;():V001T04A002. doi:10.1115/ESDA2014-20156.

Carbon nanotubes (CNTs) are considered to be one of the contemporary materials exhibiting superior mechanical, thermal and electrical properties. A new generation state-of-the-art composite material, carbon nanotube reinforced polymer (CNTRP), utilizes carbon nanotubes as the reinforcing fibre element. CNTRPs are highly promising composite materials possessing the potential to be used in various areas such as automotive, aerospace, defence, and energy sectors.

The CNTRP composite owes its frontline mechanical material properties mainly to the improvement provided by the CNT filler. There are challenging issues regarding CNTRPs such as determination of material properties, and effect of chirality and size on the mechanical material properties of carbon nanotube fibres, which warrant development of computational models. Along with the difficulties associated with experimentation on CNTs, there is paucity in the literature on the effects of chirality and size on the mechanical properties of CNTs. Insight into the aforementioned issues may be brought through computational modelling time- and cost-effectively when compared to experimentation.

This study aims to investigate the effect of chirality and size of single-walled carbon nanotubes (SWNTs) on its mechanical material properties so that their contribution to the mechanical properties of CNTRP composite may be understood more clearly. Nonlinear finite element models based on molecular mechanics using various element types substituting C-C bond are generated to develop zigzag, armchair and chiral SWNTs over a range of diameters. The predictions collected from simulations are compared to the experimental and computational studies available in the literature.

Commentary by Dr. Valentin Fuster
2014;():V001T04A003. doi:10.1115/ESDA2014-20402.

In this study non-linear thermal buckling of circular shallow arches made of functionally graded materials subjected to a linear temperature gradient is investigated. For this purpose, a functionally graded circular shallow arch is considered that its strain-displacement relation follows the Donnells nonlinear shallow shell theory. The material properties are varied smoothly through the arch thickness according to the power law distribution of the volume fraction of constituent materials. Also, material properties are considered temperature-dependent. The classical single layer theory assumptions that are reasonable for slender arches are implemented. To investigate the large deformations of such arch, the von-Karman type geometrical nonlinearity is utilized that is suitable for moderately large class of rotations. The virtual displacement principle and calculus of variation are employed to derive the governing equilibrium equations and complete set of boundary conditions of the FGM arch. The adjacent equilibrium criterion is employed for the stability analysis of the FGM arch. An analytical approach is accomplished and a closed-forms solution for thermal bifurcation points of the FGM shallow arches is presented. Also critical bifurcation loads corresponding to the critical temperatures with the presence of non-linear pre-buckling deformations is obtained. Illustrative results examine the effect of various involved parameters such as power law index, opening angle, geometric parameter (or otherwise length to thickness ratio). Obtained numerical results represent that, in most cases, thermal bifurcation for the FGM arches occurs in the high temperatures and the critical buckling temperatures are approximately high even for slender FGM arches. Also effective of ceramic or metal rich area at the bottom surface of the FGM arch is investigated and results are presented for both cases and are compared together. Varieties between this two cases due to contrast between material and structural stretching-bending coupling effect. Results presented illustrative the ceramic rich area at the bottom surface cause the higher critical buckling temperatures for the FGM arches.

Commentary by Dr. Valentin Fuster
2014;():V001T04A004. doi:10.1115/ESDA2014-20458.

A brief description of the main guidelines of the most common literature damage models is reported; in particular two uniaxial and five multi-axial damage models have been individuated from literature, which can be all used determining five parameters only, with a decisive advantage in terms of experimental effort. A Matlab®-based fatigue code has been purposely developed with the aim to receive in input the stress-strain data obtained by finite element analysis or experimentation and the constitutive parameters of the damage models, providing as output directly the residual fatigue life of the component under investigation. The paper presents the pivotal features of a numerical code, named FAST-Life, purposely developed to make the usage of these literature damage models easy and fast, and summarizes the predictions achieved with respect the estimation of the residual life of a commercial exhaust manifold made by ductile Si-Mo-Cr cast iron.

Topics: Fatigue , Cycles
Commentary by Dr. Valentin Fuster
2014;():V001T04A005. doi:10.1115/ESDA2014-20541.

Welding is used in fabrication of structures ranging from small components to large and important structures. One of the important problems associated with welded structures is development of residual stresses and deformations due to welding temperature. In fact when structures are manufactured by welding, a non-uniform temperature distribution is produced. This distribution initially causes a rapid thermal expansion followed by a thermal contraction in the weld and surrounding areas, thus generating inhomogeneous plastic deformation and residual stresses in the weldment when it is cooled. High residual stresses in regions close to the weld may promote brittle fracture, fatigue, or stress corrosion cracking. Meanwhile, distortion in base plate may reduce the buckling strength of structural members. Therefore estimating the magnitude and distribution of welding residual stresses and distortion are necessary for achieving the safest design.

In the present work an elastic-plastic finite element model considering temperature dependent mechanical properties is used to evaluate residual stresses. In this study a parametric model is adopted and the elements birth and death are used in single-pass butt welded joint to simulate the weld filler variation with time. Then numerical results are compared with experimental data.

Commentary by Dr. Valentin Fuster
2014;():V001T04A006. doi:10.1115/ESDA2014-20574.

The numerical analysis of heat transfer by finite element method (FEM) has been used widely. It is usually assumed that the parameters relevant to the heat transfer process are accurately known. However, many of these parameters may vary in a random way in reality. The reliability of the heat transfer performance is needed to be evaluated. The paper introduces an accurate, efficient sensitivity analysis method to compute the FEM response with respect to input parameters. Combining this sensitivity analysis, first order reliability method (FORM) algorithm based stochastic finite element method (SFEM) method is used to evaluate the reliability of the limit state for heat conduction of a benchmark plate with input uncertainties.

Commentary by Dr. Valentin Fuster
2014;():V001T04A007. doi:10.1115/ESDA2014-20575.

Due to the rapid development of electric and hybrid motorisations, gear manufacturers have encountered an increasing need to create high level quality gear flanks. While the main goals are to increase the load-carrying capacity and the wear resistance, reducing gear noise has become more and more important. To answer this, macro- and micro-geometry defects have long been studied as well as their effect in amplifying the vibrations of gears. However, the impact of tooth flanks micro-scale roughness on gear noise has not well been studied and understood, even though the teeth surface contacts are essential in the gear mechanics.

This paper aimed to discriminate the influence of the tooth finishing process (grinding, powerhoning) on single stage spur gear noise. A two-dimensional finite-element simulation model of a one-stage gear system was hence developed. The transmission system was composed of two identical loaded gears with one degree of freedom. Topological features of teeth surfaces finished by grinding and powerhoning were measured with a three-dimensional white light interferometer. These real topographic profiles of the tooth surfaces were integrated in the model. The meshing stiffness was determined as an output of this dynamic model. It is a parameter directly linked to the acoustic behaviour of the gear. Results show that gear noise could be reduced by the right choice of the finishing process kinematic.

Commentary by Dr. Valentin Fuster

Design

2014;():V001T05A001. doi:10.1115/ESDA2014-20082.

In the present study, we propose an innovative force gauge to replace the traditional spring sensors. The proposed force gauge is characterized numerically using commercial software Infolytica MagNet simulation analysis and then verified experimentally using a laboratory-built prototype. The results presented in this study show compared to traditional force gauge, the proposed force gauge has good measuring accuracy to replace the traditional spring sensors. As a result, the proposed method provides a promising solution for industrial applications of force measurement.

Topics: Gages
Commentary by Dr. Valentin Fuster
2014;():V001T05A002. doi:10.1115/ESDA2014-20154.

In this paper the application of biomimetic principles in design for micro manufacturing is investigated. A micro direct methanol fuel cell (μDMFC) for power generation in hearing aid devices is considered as the case study in which the bio-inspired functions are replicated. The focus in design of μDMFC is mainly on solving the problem of fuel delivery to the anode in the fuel chamber. Two different biological phenomena are suggested, and based on them different bio-inspired solutions are proposed and modeled in CAD software. Considering the manufacturing constraints and design specifications, the advantages and drawbacks of each proposed solution is discussed. Finally, the most feasible idea, in terms of manufacturing and function, is selected and an initial experimental verification is carried out.

Commentary by Dr. Valentin Fuster
2014;():V001T05A003. doi:10.1115/ESDA2014-20211.

Based on examples from research and innovation within nanotechnology, housing, bioenergy, and clothing the complexity of environmental innovation is discussed. A model for a more holistic approach to environmental innovation, which can be used both as part of innovation processes and for analyses of previous innovation processes, is developed. The approach is based on: 1) A scenario perspective on environmental aspects and impacts which implies a focus on the future roles of a product, its users and the surrounding society as imagined by the designers in their considerations about the problems addressed by the product and the solution it is offering. 2) A system’s perspective which implies a focus on the system, which a product is part of, including the need for supporting infrastructures like stakeholder training, waste management etc. 3) A lifecycle perspective to environmental aspects and impacts in order not only to capture environmental aspects from cradle to grave, e.g. related to material extraction and refining, chemical exposure during manufacturing, use and waste handling. 4) A governance perspective on management of environmental aspects and impacts, both in relation to the legitimacy of the environmental problems addressed and the solutions ‘offered’ by the product.

Commentary by Dr. Valentin Fuster
2014;():V001T05A004. doi:10.1115/ESDA2014-20224.

Design knowledge is distributed unevenly across organizational boundaries within large enterprises. Within this context, there are two main barriers to quick and reliable knowledge flow. The first is the organizational boundaries which will influence the efficiency of new design knowledge flow from when and where it is located to when and where it is need for application. The second is that one organization or sub-company of the same large enterprise often knows little about what kind of design knowledge or capability another one has. These barriers will prevent the flow of knowledge. Therefore, there is a need to develop methods and tools to improve the performance of knowledge flow within large enterprises. This paper first presents a brief introduction to the context and background information of our knowledge flow management practice in a large enterprise. Then the definition of key elements of design knowledge flow are introduced and analyzed. After that, we propose a service-based framework for the management of design knowledge flow; this framework focuses on organizing knowledge providers and developing a knowledge service platform. The proposed approach was primarily validated and verified in a large construction machinery enterprise. In addition, future work on improving the approach to knowledge flow management is also briefly discussed.

Commentary by Dr. Valentin Fuster
2014;():V001T05A005. doi:10.1115/ESDA2014-20232.

This paper summarizes a research project in the field of design and manufacturing of a water brake dynamometer for power testing facilities. In the current study, the design process of a water brake with drilled rotor disks is presented. This process is examined against the development of a water brake for a 4MW gas turbine power measurement at 15,000 RPM speed. The proposed algorithm is based on vital assumptions such as; applying product designing issues and limited modular analysis that urges the disciplinary attitude and leads to the possibility of rapid development, easy maintenance and ease of access. The final scheme is divided into six disciplines with functional classification. These disciplines are rotor, housing, cabs, pedestals, skid and accessories. Accessories, itself, consist of cooling system, lubricating system and control unit. Every discipline has its special function and could be optimized separately. It is possible to change any discipline specification without affecting other disciplines modularity. Using FEM software makes it easy to analyze the mechanical component for static and dynamic load condition regarding complex initial and boundary condition. But it is not wise to analyze whole system for designing a product due to numerical calculation errors. Besides, it is not necessary to use calculation to select machine elements. Rotor dynamics is investigated with modal analysis and related Campbell diagram. Also, transient analysis on housing, rotor and load cell arm is presented. The modal analysis on pedestals and skid is performed to predict the structural behavior under periodic loads caused by rotating unbalance. The process presented in this paper is a method for design of water brake dynamometer. Modularity presented by a product tree and a trend for design cycles associated with computer simulation are the basis of this method. The final product that is designed with this algorithm is successfully manufactured and tested.

Commentary by Dr. Valentin Fuster
2014;():V001T05A006. doi:10.1115/ESDA2014-20290.

The process of conceptualizing innovative designs is multifaceted and inherently difficult to perform successfully. It is largely characterized by the designer’s capability to find solutions to design problems beyond existing norms. General agreement suggests this process should entail a holistic approach for conceiving new ideas, which are expanded, assessed, developed, refined, and implemented as part of an iterative problem solving cycle. Suitable design procedures and skills are therefore vital as most of the final cost of a product or system is committed within the early conceptualization stage.

This paper builds on engineering design techniques previously developed by the author, namely the Design Process Framework in conjunction with the Concept Assessment Taxonomy (CAT) at the heart of concept development [1]. The main emphasis of the work presented herein is the application of said framework to a new design challenge in order to further test and demonstrate its practicality in a real world context: the conceptual development of an innovative, modular, hybrid-electric powertrain for two-wheelers.

Commentary by Dr. Valentin Fuster
2014;():V001T05A007. doi:10.1115/ESDA2014-20352.

Product design is a process of knowledge flowing and integrating. From the perspective, product design in distributed resource environment could be defined as the constructing process of a product knowledge model to satisfy specific needs of customers. This paper studies and builds structured models of product design knowledge, i.e. a customer need knowledge model, a DE knowledge model and a RU knowledge model. A product design knowledge model is the structured specification of a desired artifact including customer Need, Function with Environment (constraints), Physical principle with its Structure and Implement method and Technology detail (FEPSAT). A customer need knowledge model is constructed by customer Group feature, need Content and product Meaning (GCM). The DE knowledge model is constructed by Value, Profession, Culture and Experience background (VPCE). The RU knowledge model is built by knowledge service Content, service Input and service Output (CIO). The evolution of the product design knowledge models and the interaction with each other were analyzed.

Topics: Product design
Commentary by Dr. Valentin Fuster
2014;():V001T05A008. doi:10.1115/ESDA2014-20565.

The research project presented in this paper investigates the architectonic and constructive potential of computational design and digital fabrication in steel construction. The original contribution of this project is the development of a digital design system that solves reciprocal interlinked structures through algorithmic design and iterative processes. The system is implemented with parametric definitions that optimize the mass-customization process for laser tube technology. In order to validate the assumptions, a mock-up has been realized out of stainless steel elements. The tubes are cut by a laser-tube robotic system, then manually assembled.

Topics: Lasers , Optimization
Commentary by Dr. Valentin Fuster
2014;():V001T05A009. doi:10.1115/ESDA2014-20576.

The Design of flanges can be approached through different routes some of which [1] involve use of plate and shell theory and some [2] use concepts like “Equivalent Pressure”. A rigorous finite element analysis is a solution, but it is not always practical to do so considering the complexity of the problem and the man-hour requirement for the same. Particularly for piping systems where the number of flanges are many, an engineer always looks for a robust and easy to apply method and the method outlined in the American Boiler and Pressure Vessel Code ASME SEC III (for nuclear plants) [2], paragraph NC3658.3 provides one such method. It simply involves checking if the applied bending moment is within an allowable limit. Theoretically this method addresses the design from the standpoint of checking the bolt stress and also if the applied loading will overstress the flange. This method can easily be developed in simple spreadsheet form and is an integral part of almost every commercially available pipe stress program. The difficulty of using this method is that its applicability has been recommended in [2] as for ASME B16.5 flanges only i.e. for a maximum pipe size of 24″. Frequently an engineer encounters a pipe size which is greater than 24″ and the applicability of this method for such flanges becomes a question mark. In this paper, applicability of the NC3658.3 method for flanges >24″ has been investigated based on the standpoint of computing operating stress in bolts which is the basis of this method and also the results have been checked against finite element analysis.

Commentary by Dr. Valentin Fuster

Digital Manufacturing

2014;():V001T06A001. doi:10.1115/ESDA2014-20119.

Large Scale Dimensional Metrology (LSDM) is a branch of metrology that deals with the measurement of objects with dimensions in the order of several meters. Optical systems, relying on the use of multiple cameras and photogrammetric techniques, are among the most used instruments in this field. These systems require a preliminary calibration procedure to determine some essential parameters, such as camera positions and orientations, focal length, distortion parameters, etc. A structured comparison between two different approaches to camera calibration is herein discussed.

Topics: Calibration
Commentary by Dr. Valentin Fuster
2014;():V001T06A002. doi:10.1115/ESDA2014-20210.

Five axis machining and CAM software play key role to new manufacturing trends. Towards this direction, a series of 5 axis machining experiments were conducted in CAM environment to simulate operations and collect results for quality objectives. The experiments were designed using an L27 orthogonal array addressing four machining parameters namely tool type, stepover, lead angle and tilt angle (tool inclination angles). Resulting outputs from the experiments were used for the training and testing of a feed-forward, back-propagation neural network (FFBP-NN) towards the effort of optimizing surface deviation and machining time as quality objectives. The selected ANN inputs were the aforementioned machining parameters. The outputs were the surface deviation (SD) and machining time (tm). Experimental results were utilized to train, validate and test the ANN. Major goal is to provide results robust enough to predict optimal values for quality objectives, thus; support decision making and accurate machining modelling.

Commentary by Dr. Valentin Fuster
2014;():V001T06A003. doi:10.1115/ESDA2014-20304.

Photogrammetry has been in use for over one hundred and fifty years. This research considers how digital image capture using a medium range Nikon Digital SLR camera, can be transformed into 3D virtual spatial images, and together with additive manufacturing (AM) technology, geometric representations of the original artefact can be fabricated. The research has focused on the use of photogrammetry as opposed to laser scanning (LS), investigating the shift from LS use to a Digital Single Lens Reflex (DSLR) camera exclusively.

The basic photogrammetry equipment required is discussed, with the main objective being simplicity of execution for eventual realisation of physical products. As the processing power of computers has increased and become widely available, at affordable prices, software programs have improved, so it is now possible to digitally combine multi-view photographs, taken from 360°, into 3D virtual representational images. This has now led to the possibility of 3D images being created without LS intervention.

Two methods of digital data capture are employed and discussed, in acquiring up to 130 digital data images, taken from different angles using the DSLR camera together with the specific operating conditions in which to photograph the objects. Three case studies are documented, the first, a modern clay sculpture, whilst the other two are 3000 year old Egyptian clay artefacts and the objects were recreated using AM technology. It has been shown that with the use of a standard DSLR camera and computer software, 2D images can be converted into 3D virtual video replicas as well as solid, geometric representation of the originals.

Commentary by Dr. Valentin Fuster
2014;():V001T06A004. doi:10.1115/ESDA2014-20373.

In this study, the mold filling analyses of a thin-walled LED heat sink combined with the vacuum valve runner are simulated by FLOW-3D software. Two topics are analyzed and discussed. First, numerical simulations for variety of molding conditions, including effects of thermal conductivity, vacuum pumping pressure, mold temperature, filling velocity, respectively, are conducted for the computational model of the thin-walled LED heat sink connected with the vacuum shut-off valve. Second, effects of several geometrical parameters, including fin thicknesses of the LED heat sink and dimensions of the vacuum shut-off valve are explored. In these two topics, melts are set to liquid metal of Al 384.0 materials. The first topic of analysis mainly to investigate the effects of molding parameters based upon the same computational model of the thin-walled LED heat sink connected with a vacuum valve runner. The simulated results show if molding conditions are changed, different sizes of defects are appeared in castings; if vacuum pumping pressure is higher, the casting is also firmness, density prone to increase; if vacuum pumping pressure is too low, then pumping efficiency of mold cavity is low and it will be easy to form the casting porosity defects. For the second topic of analysis, molding conditions are hold constantly, and effects of different geometrical dimensions to castings qualifications are simulated. Characteristic dimension of trigger mechanism can effectively operate the vacuum shut-off function; but too thin or too thick of channel, it will affect the pumping time if different degrees of vacuum is imposed. Decreasing of gas residuals in castings for the vacuum pumping pressures of 760Torr, 200Torr, 100Torr compared with 10Torr, were 0.311%, 0.174%, 0.008%, respectively. It shows the appropriate and effective vacuum level for vacuum die-casting of the thin-walled LED heat sink is in the range of 100Torr.

Commentary by Dr. Valentin Fuster
2014;():V001T06A005. doi:10.1115/ESDA2014-20380.

Selective Laser Melting (SLM) is one of the Additive Manufacturing (AM) technologies applicable for producing complex geometries which are typically expensive or difficult to fabricate using conventional methods. This process has been extensively investigated experimentally for various metals and the fabrication process parameters have been established for different applications; however, fabricating 3D glass objects using SLM technology has remained a challenge so far although it could have many applications. This paper presents a summery on various experimental evaluations of a material database incorporating the build parameters of glass powder using the SLM process for jewelry applications.

Commentary by Dr. Valentin Fuster
2014;():V001T06A006. doi:10.1115/ESDA2014-20381.

Additive manufacturing (AM) technologies has brought unprecedented freedom to the fabrication of functional parts with high complex, multi-material and gradient density structure. However, currently only traditional design methods are available for AM design process, which do not take full advantage of AM capabilities. Therefore, a new design method with the consideration of all aspects of AM advantages is urgently in need. A detailed literature review on traditional design methods is presented with focused attention on the potential of using these methods to design functional parts for additive manufacturing processes. Based on thorough understanding and comparison of current structure design methods, a new design approach that integrates topological and functional optimizations for AM products is presented. With this method, an essential link is established between topological optimization result and various functional parameters of complex structure. Parts can be designed in multi levels for multi functions simultaneously. This design method provides an important foundation for future research on designing AM products with improved multiple functions and optimized topology.

Commentary by Dr. Valentin Fuster
2014;():V001T06A007. doi:10.1115/ESDA2014-20431.

Since the 3D printing technology was applied to metallic materials, the conformal cooling channel has been widely utilized for injection mold with a higher cooling efficiency. The conformal cooling channel provides higher degree of freedom in shape and size. It is more effective to apply it to convex core accumulating more heat than the concave side. However, there has not been a standard design method for the conformal cooling channel. Depending upon channel design, the cooling efficiency would not be improved. Sometimes dead flow zones could be made in the channel. Currently every engineer makes the cooling channel design of his own. In this work, we proposed an automated optimum design method for the conformal cooling channel. In the proposed design method, whole product surface is divided into smaller domains with equal thermal energy by Voronoi diagram algorithm. Then cooling channels are installed along the centers of the domains by a binary branching algorithm. The objective of the optimization was the minimization of the product surface temperature deviation. The cooling channels are branching out over the product surface through the evolutionary steps until the objective was satisfied. The injection molding CAE analysis was done by Moldflow, and the optimization by PIAnO. The sample product was an eye-glass lens product.

Topics: Cooling
Commentary by Dr. Valentin Fuster
2014;():V001T06A008. doi:10.1115/ESDA2014-20433.

Additive manufacturing technologies are being used to fabricate scaffolds with controlled architecture for tissue engineering applications. These technologies combined with computer-aided design systems enable to produce three-dimensional structures layer-by-layer in a multitude of materials. Actual prediction of the effective mechanical properties of scaffolds produced by Additive manufacturing systems, is very important for tissue engineering applications. One of the existing computer based techniques for scaffold design is topological optimisation. The goal of topological optimisation is to find the best use of material for a body that is subjected to either a single load or a multiple load distribution. This paper proposes a topological optimisation scheme based on existing micro-CT data in order to obtain the ideal topological architectures of scaffolds, maximising its mechanical behaviour under shear stress solicitations. This approach is based on micro-CT data of real biological tissues to create the loading (shear stress) and constraint surfaces of the scaffold during the topological optimisation process. This particular topological optimisation scheme uses the surface boundaries to produce novel models with different characteristics, which are different from the initial micro-CT models. This approach enables to produce valid biomimetic scaffold topologies for tissue engineering applications.

Commentary by Dr. Valentin Fuster
2014;():V001T06A009. doi:10.1115/ESDA2014-20439.

The quality assessment of manufacturing processes has been traditionally based on sample measures performed on the process output. This leads to the common “product-based Statistical Process Control (SPC)” framework. However, there are applications of actual industrial interest where post-process quality measurement procedures involve time-consuming inspections strongly related to the operator’s experience and/or based on expensive equipment. Cylindrical grinding of large rolls may be one of them. The assessment of the final acceptability of a ground cylinder, in terms of surface finish, is a challenging task with traditional measuring tools, and it often depends on operator’s visual inspections and on his subjective evaluations. In this frame, a paradigm shift is required to substitute troublesome post-process monitoring procedures with in-process and signal-based ones. The paper reviews the quality control issues in surface quality monitoring of big ground rolls where process vibrations (i.e. chatter) are one of major concerns. A multi-sensor approach for vibration onset detection, based on the use of a multi-channel implementation of the Principal Component Analysis, is proposed. The potential benefits, the implementation issues, and the main criticalities are discussed by analysing data of a real industrial application.

Topics: Sensors , Grinding
Commentary by Dr. Valentin Fuster
2014;():V001T06A010. doi:10.1115/ESDA2014-20464.

The study concerns the coating process of metal substrates in an electrostatic fluidized bed (EFB).

This eco-friendly process is profitably used to coat components of particularly complex shapes. Although this technology is widely spread in several industrial domains, the implementation of appropriate process control procedures is still object of investigation.

A model was generated from experimental data with the aim of predicting, for any set of process parameters, the resulting coating thickness of the sample. With a design of experiment (DOE) approach, the experimental investigation, that is the base for the model, quantifies the coating thickness as a function of the main process parameters namely coating time, applied voltage, and gas flow rate fed into the fluidized bed.

This study addresses the effect of the inherent uncertainties on the predicted coating thickness caused by the approximation in the model parameters. In particular, a fuzzy-logic based approach is used to describe the model uncertainties and the transformation method is used to propagate their effect on the thickness. The fuzzy results are then compared with the data produced by the experimentation leading to the evaluation of the membership level of the dataset to the uncertain model.

Commentary by Dr. Valentin Fuster
2014;():V001T06A011. doi:10.1115/ESDA2014-20484.

This paper presents a simulation study aimed at evaluating the performances of a typical Flexible manufacturing system (FMS) problems in terms of make span, average flow time, average delay time at local buffers and average machine utilization, subject to different control strategies which include routing flexibilities and dispatching rules. The routing strategies under evaluation are ‘No Alternative Routings (NAR)’; ‘Alternative Routings Dynamic (ARD)’; and ‘Alternative Routings Planned (ARP)’. The ARP rule was introduced into the FMS and coded with C++ program. The above routing strategies are combined with five dispatching rules and studied in different production volumes. Since an FMS usually deals with a variety of products, effects of changing the part mix ratio are also discussed. Simulation study was performed by using ARENA software. Finally results indicate that the ‘alternative routings planned’ strategy outperforms other routing strategies in general.

Commentary by Dr. Valentin Fuster
2014;():V001T06A012. doi:10.1115/ESDA2014-20566.

Modern flour mills continuously mix up to 80 intermediate flour streams into 3–6 final streams, whereby each intermediate stream can be allocated to only one final stream. All streams are characterized by several intensive properties and a yield. The decision for mixing allocation involves maximizing the total sale value of all final streams, such that each of them corresponds, with respect to its property ranges, to a flour that can be sold on the trade market. The decision must thereby respect any constraints on the allocation variable and on the yields of the final streams. In this work, a tool is developed that automatically performs the discrete optimization for the allocation problem and outputs the best mixing decision for the given situation. Using heuristics-based optimization, the tool respects all constraints, selects the most lucrative combination from all possible traded flours, and determines the allocation of each intermediate stream to one of the selected traded flours. The optimization method can accommodate nonlinear mixing rules. The tool can trivially be extended to other mixing allocation problems, e.g., to select input streams with minimal total cost to mix to a single output stream with specified property and yield ranges.

Topics: Optimization , Sales
Commentary by Dr. Valentin Fuster

Education

2014;():V001T08A001. doi:10.1115/ESDA2014-20060.

There has been increased interest in using problem-based pedagogies to enable design engineering undergraduates obtain a more relevant learning experience. Furthermore organizations, such as Engineers Ireland, are calling for graduate engineers to have more rounded skills in the areas of presentation, communication and team-work. However some scholars argue that design “is hard to learn and harder still to teach”. This paper provides an example of using student-industry collaboration in the teaching of product design to Mechanical Engineering final year students at the Galway-Mayo Institute of Technology (GMIT) based in Ireland. The work proposes to make an original contribution by directly interfacing with industry in order to simulate a real-life client-designer interaction for students. Finally we argue that this work contributes new insights to the debate on “pedagogies of engagement”.

Commentary by Dr. Valentin Fuster
2014;():V001T08A002. doi:10.1115/ESDA2014-20103.

Since the entrance of the graduates of technical high schools to engineering programs is hindered, in application, the graduates of general or science high schools only are accepted to engineering education. For these students, four years are not sufficient to teach the basic and the related application courses of the profession. Looking at the existing curriculum of mechanical engineering, it can be seen that in the 1st Year, the physics and chemistry courses repeat the content of the ones given in high school education. The current approach considers the students as they come to university with inadequate and incomplete knowledge and therefore not ready to follow the engineering science courses. This approach underestimates and denies the high school education contrary to the main objective of its curriculum. The main objective of high schools (secondary schools) is expressed in the Laws and Regulations with such a statement: “General high schools do not prepare students for a specific profession but rather for higher education”. Today, the existing curriculum of Mechanical Engineering is to be renewed by some new science and application courses to satisfy the demands of labor market. However, the total course credit limit prevents such a renewal. In the face of this dilemma, the answer to this question becomes important: Should the university really repeat high school physics and chemistry? In science high schools and in science branch of general high schools the science and mathematics courses have the major importance. The students are well educated on physics, chemistry, biology and mathematics. They are provided with the necessary science and mathematics background that is required in engineering education. Although only the well-educated graduates of science and general high schools are admitted to engineering programs and the students are already ready to follow the engineering science courses thanks to their high school background, unfortunately in some universities (in Turkey in all) science courses part of engineering curricula is filled by physics and chemistry courses with the same content of the ones taught in high school.

Commentary by Dr. Valentin Fuster
2014;():V001T08A003. doi:10.1115/ESDA2014-20149.

In this contribution a web-based assessment framework for CAD data is proposed which has been developed based on the experience the authors made giving undergraduate courses at a German university. The framework is the backbone of a hybrid teaching concept combining conventional classroom lessons with e-learning elements. In-between the classroom lessons the students receive instructions on a particular modeling task via a web-interface. The same interface is used to hand in solutions in form of CAD files. Teachers who need to assess these solutions are supported by a semi-automated analysis of the CAD geometry. An algorithm compares each solution with a reference solution in order to reveal typical modeling mistakes. After the assessment is completed the students receive a feedback on their work. A case study on the application of the teaching concept in a course with 691 participants held during summer term 2013 reveals the positive experience the authors made using the system and points to some issues that need to be improved in the future.

Commentary by Dr. Valentin Fuster
2014;():V001T08A004. doi:10.1115/ESDA2014-20251.

The skills of Marine Engineering graduates should be strongly oriented to problem solving for situations without external direct assistance. Marine professionals should also be able to take the right decisions under difficult situations like emergencies.

Work-group and job planning is an every day requirement, especially when doing maintenance and reparation tasks. Besides, marine technology has advanced quickly and knowledge recycling is a must on every shipping company, but operation and maintenance procedures have usually to be learnt on the go. During last decades, marine engineering students had not got immersed into a real challenge work environment until going onboard for the first time when finishing their studies. The adoption of a problem-based learning is intended to solve this situation, so students will have a closer contact with real decision-taking and auto-learning situations on earlier stages. We pretend to create more engaging experiences and introduce our students into real collaborative environments using technologies; especially those based on mobile devices and Internet tools.

Grounded in motivation theory, this research evaluates how the context of problem-based learning (PBL) affects aspects of motivation in students of marine engineering. Our research aims to answer: 1) How does the context of service in project-based learning affect student motivation? 2) What factors are most influential on student motivation to persist in project-based learning experiences?

The results show different behavior in freshmen and senior students.

Commentary by Dr. Valentin Fuster
2014;():V001T08A005. doi:10.1115/ESDA2014-20446.

Recent advances in web technology have transformed the World-Wide-Web from delivering static text to providing an easily accessible multimedia channel for dynamic, interactive communication. By using such technologies, academic teaching may evolve toward the next-generation way to transfer knowledge. At present time, there are two approaches that can be found: the Massive Open Online Courses (MOOC) approach that delivers video interactive classes to the vast audience with an open-access philosophy and Restrict-Access Courses (RAC) that deliver classes and, more important, standard degrees to limited audience [1]. While the two approaches are comparable when dealing with most academic disciplines, teaching engineering has some peculiarities that let the restricted–access course a more viable solution.

First of all, engineering schools must prepare the student for the profession. In most countries, after the degree there is a professional practice period, thus a closer relation between teacher and students allows bringing the professional knowledge embedded in the academy.

Being also a scientific discipline, engineering takes advantage from a close contact between teaching and research, especially for cutting-edge technologies. Finally, student projects are one of the most important steps of the educational path of the young engineers. Good student projects need one to one supervision, an adequate environment in particular for lab practice, and campuses that only restricted-access academies may provide.

Topics: Engineers , Teaching
Commentary by Dr. Valentin Fuster
2014;():V001T08A006. doi:10.1115/ESDA2014-20472.

Todays’ product development process is characterized by an increasing use of embedded software solutions integrated into mechatronic products. The development is more and more translocated into a virtual environment. New software methods and tools have to be developed.

Industry 4.0 is an approach to highlight the tendency of modern development. Communication between smart products, communication via internet technologies, cyber-physical systems and the Internet of Things are the basis of Industry 4.0. Owing this development, used project management methodologies have to be adjusted. In special the well-known V-Model is now extended to the W-Model to cope with the new requirements like communications between different disciplines. New approaches in virtual development have to be adapted to modern teaching techniques. Therefore a course for first semester mechanical engineering students is conducted by the department of Computer Integrated Design at the Technische Universität Darmstadt. Industry 4.0 fundamentals are taught as well as the development process underlying the so called W-Model. The students will apply this knowledge while they participate in exercises. A web-based tutorial is provided every week with different learning packages. With these learning packages, the students learn to use the project management techniques as well as software development techniques to solve different tasks. Later complex data structures and algorithms can be coded and are applied. The software development techniques, established in development of information technologies, gets more important in mechanical engineering. Therefore the students learn these aspects. Over three months length the students work in groups and use all their skills to realize a bigger software-project — a digital factory. They use a virtual testing environment (ViTMeS 3.0) to develop their solution. The presented ViTMeS 3.0 is a further development of a virtual testing environment used in last year’s team work. Later they can test their code with a real life example. This example, the digital factory, built with LEGO Mindstorms, is an important part of teaching students the foundations of communication and information techniques as well as software development and programming skills. The last step of the team work is the coding of a graphical user interface for appropriate visualization.

Commentary by Dr. Valentin Fuster
2014;():V001T08A007. doi:10.1115/ESDA2014-20549.

Student Team Challenges on specific topics are growing in popularity as efficient ways to stimulate students’ independent work, technical and management learning as well as socialization and internationalization. Many competitions are focused on ground vehicles (SAE Formula, Motostudent, Shell Eco Marathon, Solar Challenge), with different focuses on performance, fuel consumption or other depending on the aim of the event. An interesting approach is proposed in the United States by the ASME HPV Challenge, which is focused on Human Powered Vehicles. This class of vehicles allows not only to set-up a classical competition in terms of design, innovation, presentation, manufacturing and racing, but also to grow the student awareness about speed-energy relation. An HPV gives to the rider a direct feedback on a “human-scale” about energy quantities involved in personal mobility. The main returns by the use of this specific topic for a student challenge are: better understanding of the sustainable mobility problem, awareness about the potential and the limits of human muscular power, development of technical skills about design and engineering of lightweight and efficient vehicles, stimulation of the HPVs market development (the students are both potential future designers/manufacturers and/or customers), promotion of healthy and engaging physical activities. In this context, while Europe is rich of HPVs amateurs and manufacturers and is the usual location of the WHPVA World Championship, there is a lack of an educational framework involving students and teachers. Starting from the end of ZEV-HPV Erasmus Intensive Program 2011–2013, the proposal of creating a specific HPV challenge for the European students was developed by the authors. In particular, it was evaluated that by integrating the Student Challenge in the WHPVA World Championship as a special “Educational” category, many reciprocal advantages could be obtained: logistic and organizational support from the WHPVA and its national representatives, in particular for racing and timing, reciprocal technical and cultural exchange between students, academics and the hundred of amateur rider/designer/builder that were attending the event in the last decade, growth and renewal of the European HPVs community by aggregating young people around the subject and by stimulating the research of innovative solutions. After an in-depth analysis of the arguments reported above, an overview of the rules for the 1st edition of EU HPV Student Challenge will be presented and compared to analogous international competitions from an educational perspective.

Commentary by Dr. Valentin Fuster

Marine and Aerospace Applications

2014;():V001T13A001. doi:10.1115/ESDA2014-20001.

This article presents the development and design of a laser cladding machine for in-situ marine diesel engine crankshaft repairs. The described technology and device is designed to perform crankpin journal renovation operations directly in the engine housing, without removing the crankshaft from the engine. This paper outlines the novel, in-situ concept of applying laser cladding to marine crankshaft repairs. Laser cladding technology is described along with the state of laser cladding implementation in modern production engineering. The principal design of the in-situ laser cladding machine is presented and accompanied by a detailed description of the in-situ laser cladding machine construction. Arguments for the selection of appropriate laser nozzles are provided based on state-of-the-art technology. Technological challenges deriving from the industrial use of the laser equipment are outlined. The proposed device and method satisfy ship-board crankshaft surface renovation needs and open up an entirely new dimension for the industrial application of laser cladding technologies. This technology provides clear economic benefits and many technological advantages.

Commentary by Dr. Valentin Fuster
2014;():V001T13A002. doi:10.1115/ESDA2014-20068.

The usage of modern thrusters allows to combine the functions of the drive and the ship rudder in one assembly, which are separated in conventional ship propulsions. The horizontally oriented propeller is supported in a vertically rotatable nacelle, which is mounted underneath the ship hull. The propeller can directly or indirectly driven by an electric motor or combustion engine. The direct drive requires the installation of a low speed electric motor in the nacelle. The present paper concentrates on indirect drives where the driving torque is transferred by bevel gear stages and shafts from the ship to the propeller. Due to the closed and inaccessible construction high demands on the reliability have to be achieved. Especially for the design of the highly loaded bevel gear stages accurate information to the occurring loads are required. The available experience to the operation of thrusters show, that primarily rarely occurring special load cases must be considered in the design process. Such operational conditions can only be determined by expensive long-term measurements. By means of a detailed multibody system simulation model of the thruster it is already possible to develop a basic knowledge to the dynamic properties of the drive train and to determine design loads for drivetrain components.

Commentary by Dr. Valentin Fuster
2014;():V001T13A003. doi:10.1115/ESDA2014-20206.

In this research, a novel inverse design algorithm called, Elastic Surface Algorithm (ESA), is developed for viscose and inviscid external flow regimes. ESA is a physically based iterative inverse design method that uses flow analysis code to estimate the pressure distribution on the solid structure, i.e. airfoil, and a 2D solid beam finite element code to calculate the deflections due to the difference between the calculated and target pressure distribution. The proposed method is validated through the inverse design of three different airfoils. In addition, two design examples are presented to prove the robustness of the method in various flow regimes. Also, the convergence rate of this method is compared with flexible membrane method (MGM) and Ball-Spine Algorithm (BSA) methods in inviscid flow regime. The results of this study showed that not only the ESA method is an effective method for inverse design of airfoils, but also it can considerably increase the convergence rate in transonic flow regimes.

Commentary by Dr. Valentin Fuster
2014;():V001T13A004. doi:10.1115/ESDA2014-20212.

Despite the fast development and the continuous evolution of computer-aided systems for product design, analysis and manufacturing, an unlinked gap appears between the interfaces of computer-aided design (CAD) and computer-aided process planning (CAPP) modules. Various CAPP systems have been built to address this problem and forward a “passage” to link the design phase and the planning of manufacturing processes; hence, providing precise technical instructions in the shop-floor. To support the manufacturing trends and contribute to the research efforts for the realization of precise, reliable and efficient process plans, a set of programmable support functions are presented in the form of an object-oriented software application that enable process planners to produce accurate process plans for aircraft parts and components.

Commentary by Dr. Valentin Fuster
2014;():V001T13A005. doi:10.1115/ESDA2014-20254.

The paper presents the motion simulation of a Wing in Ground craft with a Lippisch configuration which is stable in terms of static stability. The influence of wind and wave perturbations on the dynamic stability of the flight are investigated.

The analysis of safety and stability used two different approaches. Based on frequency domain simulation, the first approach derived from the classical stability theory utilizes the aerodynamic coefficients and their linearized derivatives. The second approach based on time domain simulation uses the coefficients with full respect to the nonlinear character of aerodynamics in ground effect. The trajectory is used to evaluate the dynamic stability and flight safety of the craft. From the results for typical perturbations, the limitations of the classical stability theory for the flight safety of Wing in Ground craft are shown.

The results show the necessity of the automatic control system even for a satisfying stable craft predicted by the linear theory. The demand of high performance together with the hard constraints for states and control inputs are challenging for the controller design. A proportional-integral-derivative controller is studied to secure the flight safety of small craft under different perturbation and a methodology for designing a control system for operation under various weather conditions is illustrated.

Commentary by Dr. Valentin Fuster
2014;():V001T13A006. doi:10.1115/ESDA2014-20305.

The work represents a systematic numerical optimization methodology using artificial neural network and hybrid genetic algorithm for a bi-directional axial impulse turbine used in wave energy harvesting system. Reynolds-averaged Navier-Stokes equations with k-ε turbulence model were discretized and solved for unstructured tetrahedral grid elements for flow analyses. Efficiency enhancement of the turbine was chosen as an objective. The design variables chosen were numbers of stator and rotor blades. The responses obtained from CFD analysis were used to train the neural network. The optimal point search from the network by hybrid genetic algorithm produced 13% increase in turbine efficiency. Detailed description of the methodology and analysis of the results has been presented in this paper.

Commentary by Dr. Valentin Fuster
2014;():V001T13A007. doi:10.1115/ESDA2014-20450.

When flying at hypersonic speeds, it is a fundamental requirement to reduce the high drag resulting from a blunt nose cone in the ascent stage to increase the payload weight on the one hand and decrease the amount of energy needed to overcome the Earth’s gravity on the other. However, an aerospike can be attached on the front of the nose cone to obtain a high drag and heat load reduction. This study describes novel technique of an active flow control concepton nose cone with aerodisk that uses counterflowing jets to significantly modify external flowfields. In fact, this method strongly disperse the shock waves of supersonic and hypersonic vehicles to reduce aerothermal loads.Numerical simulations of a 2D axisymmetric aerodisked nose cone in hypersonic flow are conducted, and innovative techniques involving forward injection of gas from the stagnation point of the sphere are investigated; techniques include injection of various counterflowing jets (Helium and Carbon dioxide) as a coolant jet from the nose cone behind the aerodisk. In this study, the characteristics of the various jet conditions of a counterflowing jet on a cone surface were investigated numerically to improve performance of the jet on heat reduction at surface of a nose. Different Mach numbers at different altitudes have been chosen to investigate the effect of the aerospike on the nose cone’s surrounding flowfield. The drag and the heat load reduction is numerically evaluated at Mach numbers of 5.75. The results show that the lighter gas, Helium, is found to have a better cooling performance than Carbon Dioxide in low pressure ratios. The film cooling of Helium jet due to its lower specific heat capacity (Cp) character is efficient on heat load of the nose cone.

Topics: Hypersonic flow
Commentary by Dr. Valentin Fuster

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