bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrated Methodology for Investigation of Wagon Design Concepts by Simulations
Authors: Ahmad S. S. N. , Cole C. , Spiryagin M. , Sun Y. Q.
Published: January 2015

Use of simulation in the initial assessment and testing of a rail vehicle has gained popularity in recent years with the advancement of computational power and software. However, there is a lack of guidance and approved methodologies for simulation in standards around the world. Though simulation is considered a vital tool, the use of physical tests for the acceptance/certification of a vehicle design still plays the most significant part. A better understanding of simulation methodology can reduce the requirement for costly, time consuming and potentially risky physical tests. In this paper, a new three stage methodology for investigating a wagon concept has been proposed to achieve the most suitable design in line with any mandatory requirements. The three stages are the development of the multibody model of the concept wagon, a train operation simulation to obtain the critical external forces acting on the wagon and a wagon dynamics simulation. A case study has been added to demonstrate the implementation of the proposed methodology. The simulated case study shows that simulation of wagon dynamic behaviour in multibody software, combined with data obtained from longitudinal train simulation, is not only possible, but it can identify issues with a wagon design that can otherwise be overlooked.
A Novel and Simple Electrochemical Glucose Biosensor Based on a Silicon Nanowire Array Electrode
Authors: Hsu Che-Wei , Feng Wen-Chao , Chang Kang J. , Wang Gou-Jen
Published: January 2015

In this study, a novel and simple electrochemical glucose biosensor based on a silicon nanowire array (SNA) electrode was proposed. Metal-assisted etching (MAE) method using an AgNO3 and HF mixing solution as the etchant was employed to grow the silicon nanowire array (SNA) electrode. A thin gold shell is then sputtered over each silicon nanowire. Potassium ferricyanide, glucose oxidase (GOx), and a Nafion thin film were then sequentially coated onto the fabricated SNA for glucose detection. The processing time of the MAE and sputtering as well as the GOx concentration were optimized in terms of the redox peak currents of the SNA electrode. Compared with the corresponding plane gold electrode, the effective sensing area of the synthesized SNA electrode was measured to be 6.12 folds. Actual glucose detections demonstrated that the proposed SNA array electrode could operate in a linear range of 0.55 mM-11.02 mM and a very high sensitivity of 346 μA mM−1 cm−2. The proposed SNA electrode based glucose biosensor possesses advantages of simple fabrication process, low cost, and high sensitivity. It is feasible for future clinical applications.
Scoping Usage Contexts and Scenarios in Eco-Design
Authors: Telenko Cassandra , Seepersad Carolyn
Published: January 2015

Descriptions of a product’s usage context are easily understood and often provide useful information for reducing energy consumption of products. Such descriptions help inspire concept generation, explore operational issues, and evaluate prototypes. Nevertheless, characterizing the usage context as a concise but comprehensive set of factors is not a trivial task. This paper presents a taxonomy and method for characterizing the usage context and its various scenarios as sets of factors relevant to energy consumption. The taxonomy defines a general usage context as a set of human, product and situational factors that can be specified individually to create unique scenarios. The method for identifying relevant factors is grounded by first assessing variables in the fundamental physical equations that govern product operation. Then, activity diagrams reveal the elements influencing user habits and procedures. The method is demonstrated through the example of an automobile and the results are compared with existing automobile studies.
PCR Free Detection of Hepatitis B Virus DNA Using a Nanostructured Impedance Biosensor
Authors: Chen Chun-Cheng , Wang Gou-Jen
Published: January 2015

In this study, a PCR free technique for effective detection of hepatitis B virus (HBV) DNA obtained directly from clinical samples was presented. The honeycomb-like barrier layer of an anodic aluminum oxide (AAO) film having a uniform nanohemisphere array was used as the substrate of the sensing electrode. A gold thin film about 30 nm thick was radio-frequency (RF) magnetron sputtered onto the AAO barrier-layer surface as the electrode for the successive deposition of gold nanoparticles (GNPs) on the hemisphere surface. A specially designed single-strand 96-mer gene fragment of the target genomic DNA of HBV based on the genome sequences of HBV from the National Center for Biotechnology Information (NCBI) was immobilized on the nanostructured electrode as the capture probe. Complementary target HBV DNA (3020–3320 mer) obtained from clinical samples were further hybridized to the sensing probes. Detection results through electrochemical impedance spectroscopy (EIS) illustrate that two dynamic linear ranges, 0–103 and 103–105 copies/mL, having R2 values of 0.973 and 0.998, respectively, could be obtained. A detection limit of 186 copies/mL could be achieved. The proposed simple and high performance HBV DNA detection technique in this study is highly feasible for future clinical applications.
Multi-Variant Simulation of Milling of 3-D Shaped Detail Considering Changing of Workpiece Rigidity While Cutting
Authors: Kiselev Igor , Voronov Sergey , Arshinov Sergey
Published: January 2015

The examples of multi-variant simulation of 5-axis milling dynamics while the machining of 3-D shaped detail in the paper are presented. The simulation model takes into account tool and detail vibrations. The regeneration mechanism is embedded into the model. The diagram of tool speed influence on the vibration amplitudes and cutting forces magnitudes for the different area of the tool path are determined. The system dynamic parameters and the vibrations behavior and their effect on the machined surface shape for favourable and unwanted regimes are analyzed. The effect of the dynamic characteristics alteration of the workpiece while stock removal on the process behavior is considered. Some recommendations for the efficient cutting conditions setting on the base of the model application and the obtained results in the conclusion are discussed.
Gear Train Optimization of a Hybrid Electric Off-Road Vehicle
Authors: Blanco Juan C. , Gobbi Massimiliano , Muñoz Luis E.
Published: January 2015

This work presents an optimal approach to the embodiment stage of the engineering design of a gear train of a hybrid electric off-road vehicle. The powertrain of the given vehicle has a series configuration and is designed for extreme operation conditions, including narrow paths, highly irregular surface roughness and high grade scenarios. The gear train of interest has a predetermined configuration with a fixed total reduction ratio. The gear train is composed by three stages: first, a spur gear pair; in the second stage a bevel gear pair; finally in the third stage a planetary gear transmitting motion to the wheel. In addition to the structural constraints, the design optimization is strongly constrained by space limitations (packaging). The objective function is to minimize the overall mass of the gear train.

Three optimization routines were applied for the solution of this optimization problem: a gradient based optimization (GBA), genetic algorithms (GA) and a branch and bound algorithm for mixed integer problems (B&B). For the initial guess of each routine, a Sobol low discrepancy sequence (LDS) was used. After the formal statement of the optimization problem, a comparison between the performances of the different optimization algorithms is presented. The numerical results are also compared with some analytical results previously obtained.

It was found that the branch and bound algorithm developed was the most effective to find the mixed integer solution. The genetic algorithm was quite inaccurate, due to the binding geometric constraints of the problem.
Evaluating Ride Comfort for Wheelchair Passengers Utilizing a Motionbase Simulator
Authors: Vingbäck Johan , Jeppsson Peter , van Deventer Jan
Published: January 2015

Ride comfort is an important aspect of any passenger vehicle. The challenge is to provide a comfortable, yet safe, ride for the driver and the passengers and there is often a trade-off between ride comfort and safety performance.

In the case of small wheelchair-accessible vehicles the challenge increases. The weight of a wheelchair with person may span from 50 kg to 500 kg, which means that the suspension must be tuned to have a broad working range. Also, a wheelchair-accessible vehicle has many restrictions on design space and tuning possibilities due to, e.g., the space needed for the wheelchair passenger to get in and out of the vehicle. Hence, there is an additional need to evalute ride comfort and performance before the vehicle is built in order to find the optimal design. Traditionally, this is done by computer simulations of vehicle handling complemented with testing followed by chassis tuning prior to production. However, some performance parameters regarding comfort, especially in the case of wheelchair passengers, are still not well investigated and documented, and there is a need to subjectively evaluate the ride comfort in early design phases.

In this paper we investigate the use of a motionbase simulator as a platform for evaluating ride comfort with different suspension setups. We are using a reversible sleeve air suspension bellow equipped with an adaptor cylinder giving the spring characteristics. The characteristics of four different adaptors have been measured in a universal test machine. The force-compression characteristics are imported into the simulation. The simulation model used is a half-car, two-degree of freedom producing bounce and pitch movement data for either the driver or the passenger positions. The data from the simulations are used as input to a motionbase simulator for subjective assessment of the ride comfort.

The primary results indicate that a motionbase simulator can be a useful tool when designing/developing suspension systems. Also, the results indicate that a motionbase simulator is useful for investigation of comfort parameters in order to determine objective assessment of subjective parameters.
Nonlinear Oscillations and Frequency Responses of Cantilevered Piezoelectric Vibration Energy Harvesters
Authors: Yao Ming Hui , Ma Cai Xia , Zhang Wei , Cao Dong Xing
Published: January 2015

In this paper, cantilevered beam with piezoelectric layers are considered as the mechanical model of vibration energy harvesters. This paper aims to investigate the complicated dynamics behavior of the nonlinear vibrations of the cantilevered piezoelectric beam. The base excitation on the harvester beam is assumed to be harmonic load. Based on the third-order shear deformation theory and the Hamilton’s principle, the nonlinear equations of motion for the cantilevered piezoelectric beam are derived. The Galerkin’s approach is employed to discretize the partial differential equations to the ordinary differential equations with one-degree-of-freedom. The method of multiple scales is used to obtain the averaged equations in the polar form. Based on the actual work situation of the cantilevered piezoelectric beam, it is known that the base excitation plays an important role in the nonlinear vibration of the cantilevered piezoelectric beam. From the averaged equations obtained, numerical simulations are presented to investigate the effects of parameters on the steady-state responses of the cantilevered piezoelectric beam. We analyze the influences of the excitation magnitude, the excitation frequency, the piezoelectric material parameter and the damping parameter on the steady-state responses of the cantilevered piezoelectric beam. In addition, it is observed that the base excitation has significant influence on the nonlinear dynamical behavior of the cantilevered piezoelectric beam.
Secure Collaboration in Engineering Systems Design
Authors: Wang Shumiao , Bhandari Siddharth , Atallah Mikhail , Panchal Jitesh H. , Ramani Karthik
Published: January 2015

The goal in this paper is to enable collaboration in the co-design of engineering artifacts when participants are reluctant to share their design-related confidential and proprietary information with other co-designers, even though such information is needed to analyze and validate the overall design. We demonstrate the practicality of co-design by multiple entities who view the parameters of their contributions to the joint design to be confidential. In addition to satisfying this confidentiality requirement, an online co-design process must result in a design that is of the same quality as if full sharing of information had taken place between the co-designers. We present online co-design protocols that satisfy both requirements, and demonstrate their practicality using a simple example of co-design of an automotive suspension system and the tires. Our protocols do not use any cryptographic primitives — they only use the kinds of mathematical operations that are currently used in single-designer situations. The participants in the online design protocols include the co-designers, and a cloud server that facilitates the process while learning nothing about the participants’ confidential information or about the characteristics of the co-designed system. The only assumption made about this cloud server is that it does not collude with some participants against other participants. We do not assume that the server does not, on its own, attempt to compute as much information as it can about the confidential inputs and outputs of the co-design process: It can make a transcript of the protocol and later attempt to infer all possible information from it, so it is a feature of our protocols the cloud server can infer nothing from such a transcript.
Three Dimensional Modeling of the Lamination of Unfired Ceramics With Fugitive Phases
Authors: Wimmer Stephanie A. , Pan Ming-Jen , DeGiorgi Virginia G.
Published: January 2015

The dimensional accuracy of finished ceramic components depends upon the precise control of the unfired ceramic body prior to sintering. One approach for creating precise geometries is the fugitive phase approach. In the fugitive phase approach, the fugitive phase is a sacrificial material that can be removed to form channels in the finished ceramic component. In this paper, the authors computationally examine the fugitive phase approach; in particular, the lamination step of the fugitive phase approach is modeled. In the lamination step the unfired ceramic phases are combined with the fugitive phases through the application of pressure. For this research, the unfired ceramic phase consists of tape cast mullite and the fugitive phase is paper. These phases are laminated together in a die press to form a multilayer material. The compression of the die press causes pressure gradients, viscoelastic deformation, and rebounding of the unfired ceramic phases. In addition, the die press can cause movement of the fugitive phase pieces leaving unfilled voids. Three dimensional modeling is necessary to accurately capture the movement of the fugitive phase pieces. In this work the authors examine the viscoelastic deformation of the unfired ceramic phase, movement of the fugitive phase, the creation and filling of voids, pressure gradients, and the rebounding that occurs when the unfired ceramic body is removed from the die press. The information obtained from computational simulations will be used to help direct experimental investigations of the fugitive phase approach for fabrication of complex ceramic components.
Analysis of a Situational Adaptive Chassis With Respect to Maneuverability and Footprint
Authors: Schweizerhof Hans , Betz Alexander , Winner Hermann
Published: January 2015

The specifications of ground vehicles considering requirements like maneuverability and footprint are mainly caused by the target traffic. Future population distribution is subject to rural exodus resulting in megacities with the corresponding rise of traffic density and immense parking-space shortage. The problems caused by the compromise between a small footprint due to traffic requirements and a large one due to safety reasons are well known by the automotive industry as urban concept cars from different automobile exhibitions attest [1] [2] [3] [4] [5] [6] [7]. One of the known approaches is active tilt as it seems to be promising to reduce the vehicle’s dimension while coping with lateral acceleration demand and roll-over safety [4] [7]. But, active tilt represents only one solution for a situational adaptive chassis.

The proposed paper analyzes two alternative concepts, a variable track width and a variable height of the CG, and compares them to the known active tilt principle [8]. By using the exemplary maneuver of “steady-state cornering” the potential of each function concerning an increase of maneuverability and a decrease of the footprint is investigated. The results are promising and justify further investigation on the subject as for example dynamic simulation which has not been part of the study. The presented analytical examination of the influence on the yaw velocity gain and roll-over safety may open the discussion about the chances and risks of variable chassis design.
Analyzing Requirement Type Influence on Concept Quality and Quantity During Ideation: An Experimental Study
Authors: Worinkeng Emily , Summers Joshua D.
Published: January 2015

This paper examines the influence of requirement types on the quantity and quality of generated solutions as studied through a user study experiment. A controlled group of students was given a burrito folder design problem with no requirements and asked to sketch solutions. Four experimental groups given different requirement treatments were also asked to sketch solutions for the same design problem. The experimental conditions were functional requirements, non-functional requirements, mixed prioritized requirements and randomly mixed requirements. Analysis of the experimental results reveals that there is a significant difference in quantity of means between the non-functional requirements and the functional requirements groups, with the non-functional group achieving higher quantity scores. In addition, there is a significant difference in quantity in functional requirements and no requirements with the no requirements group achieving higher quantity scores. In terms of quality, there are significant differences in means between the non-functional requirement and functional requirement groups as well as the non-functional and no requirements group. Therefore having non-functional requirements can positively impact the quantity (p-value = 0.09) and the quality of concepts solutions (p-value = 0.018). These findings lead to new future research questions related to understanding exactly how the functionality, in this case functional requirements, influence an engineer’s thinking.
Type Synthesis of Compound Load Simulators Outputting the Bending Moment and Tension/Compression Force
Authors: Qu Yufeng , Yu Jingjun , Zong Guanghua , Bi Shusheng
Published: January 2015

A bending moment and a tension/compression force are two types of commonly used load patterns in loading test for mechanical components. A great number of simulator types available for the two loads have been reported widely. However, current types mainly focus on the single load pattern and only one-dimensional bending moment can be achieved. With the increasing demand of the mechanical part performance, it is urgent to build a more complex testing environment. In this situation, a novel compound load simulator capable of outputting single multi-dimensional load and compound load patterns gradually catches the attention of the researchers. The development of parallel mechanism (PM) supplies a new direction to the field of simulators, whereas there is still shortage of effective types and design principles. In this paper, type synthesis of the compound load simulators outputting the bending moment and tension/compression force is introduced. First of all, the relationship between load patterns and degree-of-freedom (DOF) of parallel mechanism is derived. Based on the derivation, the DOF correspondence with a two-dimensional pure bending moment is two-dimensional rotation and that with a tension/compression force is one-dimensional translation. Furthermore, a typical 3-PRS PM as a representative of the PM with 2R1T DOF is studied and the analysis reveals that there is parasitic motion during its two-dimensional rotation. The undesired parasitic motion will bring additional load to the part, such as shear force. Then the special characteristics of PM meeting the requirement of outputting pure bending moment are proposed. Finally, a graphical approach is utilized to synthesize the effective types of the compound simulator.
Multi-Disciplinary Design Optimization for Large-Scale Reverse Osmosis Systems
Authors: Yu Bo Yang , Honda Tomonori , Zubair Syed , Sharqawy Mostafa H. , Yang Maria C.
Published: January 2015

Large-scale desalination plants are complex systems with many inter-disciplinary interactions and different levels of sub-system hierarchy. Advanced complex systems design tools have been shown to have a positive impact on design in aerospace and automotive, but have generally not been used in the design of water systems. This work presents a multi-disciplinary design optimization approach to desalination system design to minimize the total water production cost of a 30,000m3/day capacity reverse osmosis plant situated in the Middle East, with a focus on comparing monolithic with distributed optimization architectures. A hierarchical multi-disciplinary model is constructed to capture the entire system’s functional components and subsystem interactions. Three different multi-disciplinary design optimization (MDO) architectures are then compared to find the optimal plant design that minimizes total water cost. The architectures include the monolithic architecture multidisciplinary feasible (MDF), individual disciplinary feasible (IDF) and the distributed architecture analytical target cascading (ATC). The results demonstrate that an MDF architecture was the most efficient for finding the optimal design, while a distributed MDO approach such as analytical target cascading is also a suitable approach for optimal design of desalination plants, but optimization performance may depend on initial conditions.
Application Oriented Design and Simulation of an Innovative Parallel Robot for Brachytherapy
Authors: Pisla Doina , Cocorean Dragos , Vaida Calin , Gherman Bogdan , Pisla Adrian , Plitea Nicolae
Published: January 2015

The paper presents the design and simulation of a new 5-DOF parallel robot named PARA-BRACHYROB used for brachytherapy. Brachytherapy (BT) is an advanced cancer treatment technique, where radioactive seeds are delivered directly in the tumor without damaging the proximal healthy tissues. Due to the tremendous therapeutic potential of brachytherapy, many researches are encouraged to provide solutions for enhanced placement of BT devices inside the patient body, thus further developing brachytherapy robotic systems. Therefore the paper presents an innovative CT-Scan compatible robotic device for this application. The PARA-BRACHYROB system consists of a parallel robot with five degrees of freedom (DOF) for needle positioning and orientation up to the insertion point in the patient body and a 1-DOF mechanism for the needle insertion. The kinematic models of PARA-BRACHYROB are presented and validated through a multi-body simulation including a short description of the numerical and simulation results for the developed model.
Design and Analysis of a Tendon-Driven, Under-Actuated Robotic Hand
Authors: Guo Raymond , Nguyen Vienny , Niu Lei , Bridgwater Lyndon
Published: January 2015

There has been continuous research and development to add more actuators into robotic hands to increase their dexterity. However, dexterous hands require complex control and are more costly to build. Therefore, many researchers and commercial enterprises have begun developing under-actuated robotic hands with fewer actuators and passive mechanical adaptation to not only reduce complexity and cost, but to also achieve better grasp performance in unstructured settings. This paper presents the design and analysis of the Valkyrie hand — a four fingered, tendon-driven, and under-actuated robotic hand that balances dexterity and simplicity with total 14 joints, and six degrees of actuated freedom. A derivation is provided of general dynamic and static equations for the analysis of a tendon driven mechanism, based on Euler-Lagrange formulation. The equations were used to evaluate the design parameters’ impact on the hand grasp shape and closing effort, and also validated against a design case study.
Consumer Virtual Reality for Collaborative Review of Power Plant Boiler Operation
Authors: Wang Jiaqi , Cao Muning , Dekker Gerald , Moreland John , Zhou Chenn
Published: January 2015

This research describes the motivations and technical approach for the development of a collaborative environment of a coal-fired power plant operation. The system was developed using Unity 3D to interact with power plant models and computational fluid dynamics (CFD) simulation results. The system was developed for multiple remote users to interact using the Oculus Rift and Razer Hydra for 3D display, and hand tracking. Discussion of the power plant simulation and features of the interactive system are described.
Symbolic Formulation of a Path-Following Joint for Multibody Dynamics
Authors: Hall Andrew , Schmitke Chad , McPhee John
Published: January 2015

We present a specialized multibody joint that constrains motion to a spatial path. The joint is used in the reduction of 1 degree-of-freedom systems with complex kinematics. Example applications of the joint are: the reduction of vehicle suspension systems, or the representation of biological joints. The new joint is implemented in the graph-theoretic symbolic multibody modeling environment of MapleSim and is formulated in such a way that a single ordinary differential equation is used to describe the resulting kinematic pair. A particle moving along a planar semi-circular path was chosen as the first example for successful validation of the new joint since a simple closed-form solution in terms of the path length exists. To represent arbitrary curves, the path must first be parameterized in terms of its path length. Next, a differentiable mathematical definition of the curve must be generated. B-splines are generated to define the path. For best performance we minimize the number of knots in the splines and find their optimal locations. Using the spline fitting approach, a planar parabolic path is generated and used to further analyze the performance of our implementation.
Understanding the Impact of Expert Estimation Related Uncertainties on Architecture Generation and Supplier Identification
Authors: Ye Yun , Jankovic Marija , Kremer Gül E.
Published: January 2015

The Architecture & Supplier Identification Tool (ASIT) is a design support tool enabling generation of system architectures in early design with consideration of supplier identification and evaluation. Several types of uncertainties have been considered in ASIT in order to estimate the overall uncertainty of the architectures. However, the subjective uncertainty caused by expert estimation had not been taken into account. Due to new technology integration and lack of information in early design, expert estimation is commonly used, which is also the case in the ASIT. As a considerable source of uncertainty, the consideration of subjective uncertainty may significantly influence the ASIT results, thus impacting the reliability of ASIT. This paper aims at understanding the sensitivity of the ASIT when subjective uncertainties are taken into account. The type-1 fuzzy sets and the 2-tuple fuzzy linguistic representation are selected to represent subjective uncertainties. A powertrain case study has been used to compare the results and test the sensitivity of ASIT. The comparison shows that the subjective uncertainty does not considerably influence ASIT results, and the ASIT is robust.
A Novel Experimental Setup to Apply Controlled Disturbances to Bicycle Dynamics in a Safe Environment
Authors: Kiewiet H. , Bulsink V. E. , van de Belt D. , Koopman H. F. J. M.
Published: January 2015

The SOFIE project aims to improve the understanding of bicycle and rider stability in order to increase the safety of elderly cyclists. In the framework of this project, an advanced multi-body model of bicycle and rider dynamics, including the influences of the environment, is developed. The purpose of this model is to test, in the design phase, different concepts of so-called Intelligent Assist Devices (IADs) to enhance cycling safety. The model is validated in a novel experimental setup where under controlled and safe conditions the rider and bicycle can be perturbed to identify the properties of the control mechanisms.

In the setup the rear wheel of the instrumented bicycle rotates freely on a roller bench. The front wheel rotates on a treadmill to preserve the tire-road contact[9]; steering can still be used to maintain balance. The roller bench is situated on a 6 degrees of freedom Stewart platform. The movement of the platform can be controlled in each direction. Therefore, it is possible to apply disturbances to the roll, pitch and yaw and to apply lateral, posterior and superior disturbances to the bicycle with a predetermined multisine disturbance signal.

The bicycle is equipped with sufficient inertial sensors to accurately estimate the current orientations. Furthermore, the laboratory setup allows utilizing a marker-based video system to measure subject and bicycle movements in a global frame. The subject is secured in a safety harness. By analysing experiments in this setup in the mathematical model, the experiments may serve as validation data.

Preliminary results showed that it is well possible to perform perturbation experiments; the actual modelling of the tyre-floor contact proves important in determining the response. Further experiments will be done to estimate the properties of the control system in different categories of riders using system identification, allowing differences between young and elderly subjects to be studied. Subsequently, with the novel experimental setup it is possible to evaluate IADs.
Test and Validation of a Nonlinear Electromagnetic Energy Harvester
Authors: Bendame Mohamed , Abdel-Rahman Eihab , Soliman Mostafa
Published: January 2015

We investigate a new type of nonlinear vibration energy harvester that uses a double impact oscillator as its harvesting element. A prototype of the harvester is analyzed numerically and experimentally when aligned vertically. Results show that the new architecture enhanced the output power as well as the frequency bandwidth in comparison with linear harvesters. The new harvester is capable of generating up to 250 mV and has a harvesting bandwidth of about 6 Hz. The optimal load for 0.7 g input acceleration is found to be 5.5 Ω and the corresponding optimal power is determined to be 8 mWatts.
Modal Analysis Using Implicit Boundary Finite Element Methods
Authors: Zhang Zhiyuan , Kumar Ashok V.
Published: January 2015

Modal analysis is widely used for linear dynamic analysis of structures. The finite element method is used to numerically compute stiffness and mass matrices and the corresponding eigenvalue problem is solved to determine the natural frequencies and mode shapes of vibration. Implicit boundary method was developed to use equations of the boundary to apply boundary conditions and loads so that a background mesh can be used for analysis. A background mesh is easier to generate because the elements do not have to conform to the given geometry and therefore uniform regular shaped elements can be used. In this paper, we show that this approach is suitable for modal analysis and modal superposition techniques as well. Furthermore, the implicit boundary method also allows higher order elements that use B-spline approximations. Several test examples are studied for verification.
Simulation of Non-Nominal Welds by Resolving the Melted Zone and its Implication to Variation Simulation
Authors: Lorin Samuel , Cromvik Christoffer , Edelvik Fredrik , Lindkvist Lars , Söderberg Rikard , Wärmefjord Kristina
Published: January 2015

The prediction of geometric variation and its consequences is one important aspect of product development. For welded assemblies it has been shown that positioning errors of the parts prior to welding affects the weld-induced distortion. Therefore, to accurately predict geometric variation in welded assemblies, variation simulation and welding simulation need to be performed in combination. This is usually a very time consuming task, and therefore, the relatively fast SCV-method is utilized. This method is used to calculate welding distortion when positioning errors are present and it consists of the following three steps: 1) a steady state computation of the thermal distribution during welding, 2) the melted zone along the full joint is encapsulated by sweeping a two-dimensional convex hull along the weld gun path, and 3) a uniform temperature is applied to all nodes inside this zone. The two-dimensional convex hull is computed so that when swept along the weld path, it will encapsulate the melted zone from the steady state temperature computation. The weld-induced distortion is obtained from the elastic volumetric shrinkage. In this article the focus is on the first step in this method; the temperature distribution computation. The positioning error can cause the connecting parts to have varying distances to each other at the joint, which cause the melted region to vary along the weld path. Therefore, it is not sufficient to capture the steady state temperature distribution at only one location. Depending on the geometry surrounding the weld path, several locations may be needed. In this new approach, the two-dimensional convex hull that is to be swept along the weld path, can vary along the weld path, and is computed from an interpolation of the multiple two-dimensional convex hulls obtained from the multiple steady state temperature computations. A comparison of the melted region using transient temperature calculation, a single steady state temperature calculation and this new approach has been made. Furthermore, the implication on distortion calculation has been studied.
New Synthesis Approach for Expandable Polyhedral Linkages
Authors: Zhang Ying , Su Hai-Jun , Liao Qizheng , Wei Shimin , Li Weiqing
Published: January 2015

This paper presents a new synthesis approach for expandable polyhedral linkages, which are synthesized by inserting appropriate link groups into the faces of polyhedron and interconnecting them by a special composite hinges (called gusset by K. Wohlhart). The overconstrained expandable polyhedral linkages are movable with one degree of freedom (DOF).The link groups are single DOF scaling planar linkages. The gussets are multiple rotary joints whose axes converge at the corresponding vertices of the polyhedron and the number of the rotary joints equals the one of the faces which meet at the vertices. This new approach is suitable for any polyhedron whatever is regular or irregular polyhedron. To verify this new approach, the expandable regular hexahedral linkage is modeled in the SolidWorks and its mobility are studied based on screw theory and topology graph.
New Metrics for Pit Shape Characterization
Authors: DeGiorgi Virginia G. , Qidwai Siddiq M. , Kota Nithyanand
Published: January 2015

Currently a variety of approaches are used to match stress concentration factors with corrosion pit geometry. The majority of these approaches use standardized stress concentration factors, such as concentration factors for circles or ellipses, to estimate the maximum stress values along the pit front. These factors are based on regular geometric shapes. Pits that form in a microstructure are influenced by the individual grains surrounding the pit. These pits often do not have simple shapes. Use of standardized geometric factors do not capture the geometric complexity of the pit. Rather than a single parameter, such as a the aspect ratio of an ellipse, multiple parameters may be required to define the extent and variation in localized curvature along a pit front within a microstructure. Maximum depth and curvature are just two possible candidate metrics. In addition the authors looked to the medical field for potential metrics to adequately describe the convoluted nature of the pit front. Several methods have been developed to mathematically define the serpentine twists in diseased retinal blood vessels. In this work the authors present a methodology for determining characteristics including tortuosity of computationally predicted pit shapes embedded in microstructures. Ultimately it is hoped that maximum curvature, pit tortuosity and other geometric based metrics can be combined to predict the maximum rise in stress associated with a pit embedded in a microstructure.
Design and Analysis of a Self-Folding SMA-SMP Composite Laminate
Authors: Saunders Robert , Hartl Darren , Malak Richard , Lagoudas Dimitris
Published: January 2015

Shape memory alloy (SMA) wires have the ability to create large actuation forces and displacements. When arranged in a planar configuration (e.g., in a mesh) and embedded near the surface of a polymer matrix, they can be used to create flat sheets that are self-folding and reconfigurable. Shape memory polymers (SMP) exhibit changes in material properties that allow them soften when heated above their glass transition temperature and then freeze when cooled back below it, retaining any deformation applied when they were softened. This work considers the design and analysis of key engineering features of a shape memory composite (SMC) laminate consisting of thermally activated SMA wires in a mesh pattern embedded in such an SMP matrix. Such a laminate would represent a relatively stiff reconfigurable structure with no need for continued power to retain actuated shapes. The results of the design study described herein will be an optimized configuration that maximizes the deflection of the laminate in its locked state while respecting conventional constraints against overstressing and overheating the SMA and SMP materials.
Reduced Material Model of Composite Laminates for 3D Finite Element Analysis
Authors: Kumar Goldy , Shapiro Vadim
Published: January 2015

Laminate composites are widely used in automotive, aerospace, medical, and increasingly in consumer industries, due to their reduced weight, superior structural properties and cost-effectiveness. However, structural analysis of complex laminate structures remains challenging. 2D finite element methods based on plate and shell theories may be accurate and efficient, but they generally do not apply to the whole structure, and require identification and preprocessing (dimensional reduction) of the regions where the underlying assumptions hold. Differences in and limitations of theories for thin/thick plates and shells further complicate modeling and simulation of composites. Fully automated structural analysis using 3D elements with sufficiently high order basis functions is possible in principle, but is rarely practiced due to the significant increase in computational integration cost in the presence of a large number of laminate plies.

We propose to replace the actual layup of the laminate structure by a simplified material model, allowing for a substantial reduction of the computational cost of 3D FEA. The reduced model, under the usual assumptions made in lamination theory, has the same constitutive relationship as the corresponding 2D plate model of the original laminate, but requires only a small fraction of computational integration costs in 3D FEA. We describe implementation of 3D FEA using the reduced material model in a meshfree system using second order B-spline basis functions. Finally, we demonstrate its validity by showing agreement between computed and known results for standard problems.
A Complementarity Based Contact Model for Geometrically Accurate Treatment of Polytopes in Simulation
Authors: Williams Jedediyah , Lu Ying , Trinkle Jeffrey C.
Published: January 2015

We present a contact model for rigid-body simulation that considers the local geometry at points of contact between convex polyhedra in order to improve physical fidelity and stability of simulation. This model formulates contact constraints as sets of complementarity problems in a novel way, avoiding or correcting the pitfalls of previous models. We begin by providing insight into the special considerations of collision detection needed to prevent interpenetration of bodies during time-stepping simulation. Then, three fundamental complementarity based contact constraints are presented which provide the foundation for our model. We then provide general formulations for 2D and 3D which accurately represent the complete set of physically feasible contact interactions in six unique configurations. Finally, experimental results are presented which demonstrate the improved accuracy of our model compared to four others.
Vibration of Micro-Scale Structures: Accurate SPH Approach and Simplified Generalized Kelvin Model
Authors: Cramer Nick , Teodorescu M.
Published: January 2015

Recent advances in polymer technology together with the growing need of smaller and lighter electronic components and biomedical equipment led to the development of new applications of polymers at micro scale. However, unlike traditional materials (e.g., metal silicon), polymers exhibit a significant time dependency in their response to load (e.g., viscoelastic, hyperelastic). Therefore, predicting the behavior of such polymer components at small scale requires accurate simulations of the effects of creep and relaxation within the systems. The current study uses a mesh-free particle method (smoothed particle hydrodynamics) to predict time-dependent mechanical response of polymers. As a first step towards investigating the response of a polymer microstructure under load, we simulate the behavior of a slender polymer rod compressed and tangentially dragged against a smooth glass surface.

It is shown that although accurate prediction of polymer deformation cannot be achieved with a fully analytic model, a simplified generalized Kelvin model could calibrated to capture most of the characteristics of the fully numerical model. This cold be used for predicting the behavior under load of a passive subsystem of imbedded in a control algorithm to extend the measuring domain of a possible sensor or prevent potentially dangerous operating conditions.
Challenges of Incorporating Guided-Inquiry Learning in an Engineering Optimization Class
Authors: English Kenneth W.
Published: January 2015

This paper describes the introduction and impact of using process oriented guided inquiry learning (POGIL) to increase student engagement in a graduate level engineering optimization class. POGIL exercises were introduced into the class as an effort to enhance student engagement and improve retention of knowledge. The effort revealed that although POGIL has been adopted in many contexts (e.g, materials science, chemical engineering, and computer science), characteristics of the student population and the course may play a significant role in the success of a POGIL implementation. The paper describes the POGIL method, how it was adapted for inclusion in an optimization class, and observations on classroom impacts, engagement, and effectiveness.
Ontological Knowledge Representation and Inference Rules for MTM Decision Support System
Authors: Renu Rahul , Mocko Gregory
Published: January 2015

The objective of the research presented is to develop and implement an ontological knowledge representation for Methods-Time Measurement assembly time estimation process. The knowledge representation is used to drive a decision support system that provides the user with intelligent MTM table suggestions based on assembly work instructions. Inference rules are used to map work instructions to MTM tables. An explicit definition of the assembly time estimation domain is required. The contribution of this research, in addition to the decision support system, is an extensible knowledge representation that models work instructions, MTM tables and mapping rules between the two which will enable the establishment of assembly time estimates. Further, the ontology provides an extensible knowledge representation framework for linking time studies and assembly processes.
Physics Engines Evaluation Based on Model Representation Analysis
Authors: Badillo Germánico González , Castillo Hugo I. Medellín , Lim Theodore , López Víctor E. Espinoza
Published: January 2015

Virtual environments (VE) are becoming a popular way to interact with virtual objects in several applications such as design, training, planning, etc. Physics simulation engines (PSE) used in games development can be used to increase the realism in virtual environments (VE) by enabling the virtual objects with dynamic behavior and collision detection. There exist several PSE available to be integrated with VE, each PSE uses different model representation methods to create the collision shape and compute virtual object dynamic behavior. The performance of physics based VEs is directly related to the PSE ability and its method to represent virtual objects. This paper analyzes different freely available PSEs — Bullet and the two latest versions of PhysX (v2.8 and 3.1) — based on their model representation algorithms, and evaluates them by performing various assembly tasks with different geometry complexity. The evaluation is based on the collision detection performance and their influence on haptic-virtual assembly process. The results have allowed the identification of the strengths and weaknesses of each PSE according to its representation method.
Designing Scalable Product Families for Black-Box Functions
Authors: Pirmoradi Zhila , Hajikolaei Kambiz Haji , Wang G. Gary
Published: January 2015

Product family design optimization is a cost-efficient concept for achieving the best tradeoff between commonalization and diversification of products. When design functions are computationally intensive and thus viewed as black-boxes, the product family design becomes more challenging. In this study a two-stage platform configuration and product family design optimization method with generalized commonality is proposed for scale-based families involving black-box functions. The platform configuration is unknown and multiple sub-platforms are allowed. In this study, the main parameters used towards the family design include a non-conventional sensitivity analysis, the detachability property of each variable, and the variation of individual optimal values for each design variable. Metamodeling techniques are employed to provide both the non-conventional sensitivity and correlation intensities information, which leads to significant savings in the number of function calls. Efficiency of this method is tested through designing a scalable family of universal electric motors. Compared to a number of previously developed methods, the proposed method yields a design solution with acceptable performance loss after commonalization, and better value for the aggregated preference objective function while satisfying all the performance constraints.
The Hydrogen Molecular Ion With Time-Dependent Magnetic Field Strength as Control
Authors: Kime Katherine A.
Published: January 2015

We consider the hydrogen molecular ion with time-dependent magnetic field strength. We discretize the corresponding Schroedinger equation with the Hamiltonian written in prolate spheroidal coordinates. We formulate a control problem and give an example of steering a restricted initial state to a restricted terminal state.