bluuebunny/crossref_metadata_2025 huggingface dataset:
Policy Design for Sustainable Energy Systems Considering Multiple Objectives and Incomplete Preferences
Authors: Hawthorne Bryant D. , Panchal Jitesh H.
Published: September 2013

The focus of this paper is on policy design problems related to large scale complex systems such as the decentralized energy infrastructure. In such systems, the policy affects the technical decisions made by stakeholders (e.g., energy producers), and the stakeholders are coordinated by market mechanisms. The decentralized decisions of the stakeholders affect the sustainability of the overall system. Hence, appropriate design of policies is an important aspect of achieving sustainability. The state-of-the-art computational approach to policy design problem is to model them as bilevel programs, specifically mathematical programs with equilibrium constraints. However, this approach is limited to single-objective policy design problems and is based on the assumption that the policy designer has complete information of the stakeholders’ preferences. In this paper, we take a step towards addressing these two limitations. We present a formulation based on the integration of multi-objective mathematical programs with equilibrium constraints with games with vector payoffs, and Nash equilibra of games with incomplete preferences. The formulation, along with a simple solution approach, is presented using an illustrative example from the design of feed-in-tariff (FIT) policy with two stakeholders. The contributions of this paper include a mathematical formulation of the FIT policy, the extension of computational policy design problems to multiple objectives, and the consideration of incomplete preferences of stakeholders.
Nonlinear System Identification of Frictional Connections in a Bolted Beam Assembly
Authors: Eriten Melih , Kurt Mehmet , Luo Guanyang , McFarland Donald M. , Bergman Lawrence A. , Vakakis Alexander F.
Published: September 2013

In modern structures, mechanical joints are ubiquitous, significantly influencing a structure’s dynamics. Frictional connections contained in a joint provide coupling of forces and moments between assembled components as well as localized nonlinear energy dissipation. Certain aspects of the mechanics of these friction connections are yet to be fully understood and characterized in a dynamical systems framework. This work applies a nonlinear system identification (NSI) technique to characterize the influence of frictional connections on the dynamics of a bolted beam assembly. The methodology utilized in this work combines experimental measurements with slow-flow dynamic analysis and empirical mode decomposition, and reconstructs the dynamics through reduced-order models. These are in the form of single-degree-of-freedom linear oscillators (termed intrinsic modal oscillators — IMOs) with forcing terms derived directly from the experimental measurements through slow-flow analysis. The derived reduced order models are capable of reproducing the measured dynamics, whereas the forcing terms provide important information about nonlinear damping effects. The NSI methodology is applied to model nonlinear friction effects in a bolted beam assembly. A ‘monolithic’ beam with identical geometric and material properties is also tested for comparison. Three different forcing (energy) levels are considered in the tests in order to study the energy-dependencies of the damping nonlinearities induced in the beam from the bolted joint. In all cases, the NSI technique employed is successful in identifying the damping nonlinearities, their spatial distributions and their effects on the vibration modes of the structural component.
Two-Degree-of-Freedom Decoupled Non-Redundant Cable-Loop-Driven Parallel Mechanism
Authors: Liu Hanwei , Gosselin Clément , Laliberté Thierry
Published: September 2013

A novel two-degree-of-freedom cable-loop slider-driven parallel mechanism is introduced in this paper. The two degrees of freedom of the mechanism are decoupled and only two actuators are needed to control the motion. There are two cable loops for each direction of motion: one acts as the actuating loop while the other is the constraint loop. Due to the simple geometric design, the kinematic and static equations of the mechanism are very compact. The stiffness of the mechanism is also analyzed in the paper. It can be observed that the mechanism’s stiffness is much higher than the stiffness of the cables. Finally, the dynamic equations of the mechanism, including the compliance and the damping of the cables are obtained. The proposed mechanism’s workspace is essentially equal to its footprint and there are no singularities. The mechanism does not require the use of a rigid-link passive bridge and trolley (only cables are connected to the end-effector). Sliders located on the edges of the workspace are used and actuation redundancy is eliminated while providing force closure everywhere in the workspace.
Large Stroke Performance Optimization of Spatial Flexure Hinges
Authors: Wiersma D. H. , Boer S. E. , Aarts R. G. K. M. , Brouwer D. M.
Published: September 2013

Flexure hinges inherently lose stiffness in supporting directions when deflected. In this paper a method is presented for optimizing the geometry of flexure hinges, while supporting stiffnesses are retained. These hinges are subjected to a load and deflected an angle of up to ±20°. The measure of performance is defined by the first unwanted eigenfrequency, which is closely related to the supporting stiffnesses. During the optimization, constraints are applied to the actuation moment and the maximum occurring stress. Evaluations of three cross flexure hinge types and a butterfly flexure hinge are presented. A flexible multibody modeling approach is used for efficient modeling. Each of these hinge types is described by a parameterized geometric model. The obtained optimal hinge designs are validated with a finite element model and show good agreement. The optimal solution of the butterfly flexure hinge shows the least decrease in the supporting stiffnesses of the evaluated hinges.
An Imperfect Microbeam Electrically Actuated: Experimental Investigation and Parameter Identification
Authors: Ruzziconi Laura , Bataineh Ahmad M. , Younis Mohammad I. , Lenci Stefano
Published: September 2013

In this study we present a theoretical and experimental investigation of a microelectromechanical system (MEMS). The device is constituted of a clamped-clamped polysilicon microbeam electrostatically and electrodynamically actuated. The microbeam has imperfections in the geometry, which are related to the microfabrication process. Using a laser Doppler vibrometer, experimental testing based on forward and backward sweeps is conducted in a neighborhood of the first symmetric natural frequency. Our aim is that of introducing a simple mechanical model, which, despite the inevitable approximations, is able to catch and predict the most relevant aspects of the device response. Many parameters of the microbeam are unknown. Their values are identified by developing a parametric analysis, which is based on matching the experimental natural frequencies and the experimental frequency response diagrams. Extensive simulations are performed. Theoretical and experimental frequency responses are analyzed in detail at increasing values of electrodynamic excitation. A satisfactory concurrence of results is achieved, not only at low electrodynamic loads, but also at higher ones, when the escape (dynamic pull-in) becomes impending. This confirms that, despite the apparent simplicity, the proposed theoretical model is able to simulate the complex dynamics of the device accurately and properly.
Foundation for Model Integration: Semantic Backplane
Authors: Simko Gabor , Levendovszky Tihamer , Neema Sandeep , Jackson Ethan , Bapty Ted , Porter Joseph , Sztipanovits Janos
Published: September 2013

One of the primary goals of the Adaptive Vehicle Make (AVM) program of DARPA is the construction of a model-based design flow and tool chain, META, that will provide significant productivity increase in the development of complex cyber-physical systems. In model-based design, modeling languages and their underlying semantics play fundamental role in achieving compositionality. A significant challenge in the META design flow is the heterogeneity of the design space. This challenge is compounded by the need for rapidly evolving the design flow and the suite of modeling languages supporting it. Heterogeneity of models and modeling languages is addressed by the development of a model integration language – CyPhy – supporting constructs needed for modeling the interactions among different modeling domains. CyPhy targets simplicity: only those abstractions are imported from the individual modeling domains to CyPhy that are required for expressing relationships across sub-domains. This “semantic interface” between CyPhy and the modeling domains is formally defined, evolved as needed and verified for essential properties (such as well-formedness and invariance). Due to the need for rapid evolvability, defining semantics for CyPhy is not a “one-shot” activity; updates, revisions and extensions are ongoing and their correctness has significant implications on the overall consistency of the META tool chain. The focus of this paper is the methods and tools used for this purpose: the META Semantic Backplane. The Semantic Backplane is based on a mathematical framework provided by term algebra and logics, incorporates a tool suite for specifying, validating and using formal structural and behavioral semantics of modeling languages, and includes a library of metamodels and specifications of model transformations.
Jacobian Analysis of a Fully Decoupled Parallel Manipulator for Minimally Invasive Surgery
Authors: Kuo Chin-Hsing , Dai Jian S.
Published: September 2013

This paper presents the Jacobian analysis of a parallel manipulator that has a fully decoupled 4-DOF remote center-of-motion for application in minimally invasive surgery. Owing to the special structure of the manipulator, the Jacobian matrix of the manipulator is expressed as a combination of three special Jacobian matrices, namely the Jacobian of motion space, Jacobian of constraints, and Jacobian of actuations. Based on these Jacobian matrices, the singular configurations of the manipulator are then identified. It shows that the configuration singularity only exists at the central point and the boundary of the reachable workspace of the manipulator.
Characterization and Scaling of Low Velocity Impact Response of Structures With Local Plastic Deformation: Implications for Design
Authors: Christoforou Andreas P. , Yigit Ahmet S. , Majeed Majed
Published: September 2013

This paper presents a methodology for the characterization and scaling of response of structures having different shapes, sizes, and boundary conditions that are under impact by blunt objects through a characterization diagram. The diagram is constructed from an analytical functional relationship of the normalized maximum impact force and three non-dimensional parameters, namely the ‘Relative Stiffness’, ‘Relative Mobility,’ and ‘Effective Mass Ratio’. The efficacy of this diagram, which is developed using simple structural models, is demonstrated by FE simulations of more complicated and realistic structures and boundary conditions (clamped, stiffened plates and cylindrical panels). All the necessary parameters needed for characterization are determined using FE models simulating real-world experiments. The characterization method is validated for a wide range of impact parameters that cover the entire dynamic spectrum. It is expected that by determining the model parameters for various engineering structural elements and support conditions, the impact response and subsequent damage may be predicted in an early stage using the characterization diagram. The diagram can also be used to assess the accuracy of simple lumped parameter models and to provide clear guidelines for the choice of an adequate model for a given impact situation. As a result, the characterization diagram and simple models can be used for both the evaluation of finite element and other solutions, and as guides in the design of experiments and in scaling experimental results. The characterization diagram can be used as a powerful analytical prediction tool in various stages of design of complex structures subject to impact such as, initial design, testing and commissioning.
Finite Element Synthesis for Design Optimization
Authors: Saad Mahmoud R. , Metwalli Sayed M.
Published: September 2013

The present work introduces a new Finite Element methodology that can be used directly in calculating and optimizing the thickness of a mechanical structure. This method depends on the constant strain triangle model after assuming different thicknesses at the elements nodes. A linear relation between the nodes thicknesses is assumed and a new stiffness matrix is created. Nodes thicknesses are optimized using the developed HGP method to reach uniform stress among the structure to satisfy the constrained allowable stress designated by the designer. Examples and sample applications are employed for comparisons and their results culminate in removing unnecessary elements and increasing the thickness, which is subjected to high stresses. Results indicate marked improvements and potential for topology optimization.
Optimal Base Placement and Motion Planning for Mobile Manipulators
Authors: Du Bin , Zhao Jing , Song Chunyu
Published: September 2013

A mobile manipulator typically consists of a mobile platform and a robotic manipulator mounted on the platform. The base placement of the platform has a great influence on whether the manipulator can perform a given task. In view of the issue, a new approach to optimize the base placement for a specified task is proposed in this paper. Firstly, the workspace of a redundant manipulator is investigated. The manipulation capability of the redundant manipulator is maximized based on the manipulability index through the joint self-motion of the redundant manipulator. Then the maximum manipulation capability in the specified work point is determined. Next, the relative manipulability index (RMI) is defined for analyzing manipulation capability of the manipulator in its workspace, and the global manipulability map (GMM) is presented based on the above measure. Moreover, the optimal base placement related to the given task is obtained, and the motion planning is implemented by an improved rapidly-exploring random tree (RRT) algorithm with the RMI, which can enhance the manipulation capability from the initial point to the target point. Finally, the feasibility of the proposed algorithm is illustrated with numerical simulations and experiments on the mobile manipulator.
A Point-Structured Geometric Modeling Approach to Foot Shape Representation
Authors: Tsai Ming J. , Lee Hung W. , Lung Hsueh Y.
Published: September 2013

A compact representation for the quantitative description of foot shape is important not only for the foot measurement and anthropometry, but also for the ergonomic design of footwear. Based on foot scanned data, a novel point-structured geometric modeling approach to the reduction of 3D point cloud and the preservation of shape information is proposed. The semantic descriptions of foot features are interpreted into logical definitions. A total of fifteen feature points are thus defined. Finally, there are only a total of 2,093 data points needed in such a point-structured representation. Based on it, it is easy to fetch not only the 1D and 2D measurements, but also the 3D feature curves of the foot shape. It can provide a compact 3D geometric model to serve as a significant database for the individuals and, thereby, becomes a useful tool in investigating the foot and manufacturing the foot related apparel and devices.
On Design Preference Elicitation With Crowd Implicit Feedback
Authors: Ren Yi , Papalambros Panos Y.
Published: September 2013

We define preference elicitation as an interaction, consisting of a sequence of computer queries and human implicit feedback (binary choices), from which the user’s most preferred design can be elicited. The difficulty of this problem is that, while a human-computer interaction must be short to be effective, query algorithms usually require lengthy interactions to perform well. We address this problem in two steps. A black-box optimization approach is introduced: The query algorithm retrieves and updates a user preference model during the interaction and creates the next query containing designs that are both likely to be preferred and different from existing ones. Next, a heuristic based on accumulated elicitations from previous users is employed to shorten the current elicitation by querying preferred designs from previous users (the “crowd”) who share similar preferences to the current one.
Comparing the Perspectives of Engineering Students, Business Students, and Faculty Advisors Toward Successful Planning of Capstone Projects
Authors: Harper Steven , Nagel Robert L.
Published: September 2013

One of the common goals in engineering design education is to provide real-world experiences that mimic the design experiences a student might encounter once graduated. An approach we use in the School of Engineering (SOE) at James Madison University (JMU) is a multidisciplinary pairing of business students from the College of Business and engineering students from the School of Engineering. Engineering and business students are positioned to learn from each other, and to collaborate together as they develop a feasible project plan for a two-year engineering project. In this paper, we present a study investigating the differing perceptions between faculty advisors, engineering students, and business students related to the successful capstone plan development. We hypothesized that each of the different functional groups (business students, engineering students, and faculty advisors) would have different view points on the planning and status of the infant capstone projects. The results indicate that, in the areas of planning and scheduling, the advisors are grouped with the engineering students, and in the areas of directing and controlling, the advisors are grouped with the business students. The time horizon of the students guides how they view unresolved problems with the planning and status of the project. This led to the business students, who were on the project for only one semester, to stand apart in their pessimistic assessment of the planning and scheduling of the project. The engineering students, who are on the project for the full two years, tended to be more optimistic about the directing and controlling aspects of the project.
Type Synthesis of Variable Degrees-of-Freedom Parallel Manipulators With Both Planar and 3T1R Operation Modes
Authors: Kong Xianwen
Published: September 2013

Parallel manipulators (PMs) with multiple operation modes are novel reconfigurable PMs which use less number of actuators and can be reconfigured without disassembly. Although several classes of PMs with multiple operation modes that have the same DOF (degrees-of-freedom) in all the operation modes have been proposed, only one class of variable-DOF PMs with multiple operation modes — PMs with multiple operation modes that do not have the same DOF in all the operation modes — have been proposed so far. This paper deals with the type synthesis of variable-DOF PMs with both planar and 3T1R (or Schönflies motion which has three translational DOF and 1 rotational DOF) operation modes. The axes of rotation of the moving platform in the planar operation mode are not parallel to the axes of rotation of the moving platform in the 3T1R operation mode. At first, an approach to the type synthesis of PMs with multiple operation modes is recalled. Based on the results on the type synthesis of planar PMs and 3T1R PMs, the types of variable-DOF PMs with both planar and 3T1R operation modes are then obtained. This work can be extended to the type synthesis of other classes of PMs with multiple operation modes.
An Algorithmic Approach to Teaching Functionality
Authors: Nagel Robert L. , Bohm Matt R. , Cole Josh , Shepard Phillip
Published: September 2013

The consideration of function is prevalent across numerous domains as a technique allowing complex problems to be abstracted into a form more readily solvable. In engineering design, functional models tend to be of a more generalized nature, and consequently, engineering design derived functional representations do not aim to replace domain specific models but to encapsulate those models at a higher and more integrated system level. While the value of function in engineering design seems to be generally recognized, it remains a difficult concept to teach to students of engineering design. In this paper, an algorithmic approach to teaching function and functional model generation is presented. The approach uses a series of grammar rules to assemble function chains from a list of enumerated functions desired of the final product. Function chains can then be aggregated into a complete functional model. The approach has been trialed with senior capstone design students taught about functionality as well as how to generate a black box model and how to enumerate functions. Student-generated functional models are compared to expert generated functional models in the paper. Preliminary results indicate that a student with limited functional modeling experience could follow the prescribed algorithm to generate an aggregated functional model based solely on a black box model.
Nonlinear Material Modeling of a Truck Tire, Pavement and its Effect on Contact Stresses
Authors: Kim Seunghye , Kim Kwangwon , Ju Jaehyung , Kim Doo-Man
Published: September 2013

For an accurate evaluation of the failure stress of tire and pavement materials, both the tire and pavement need to be modeled as nonlinear materials. In this study, a hyperelastic model of a truck tire and an elasto-viscoplastic model for pavement are implemented and their interaction effect on contact stresses is investigated. Finite element (FE) analysis with ABAQUS is used to simulate the interaction models of the truck tire and pavement. The interaction of hyperelastic and elasto-viscoplastic models for a truck tire and pavement shows accurate contact pressure for the truck tire and accurate stress distribution of the pavement.
Lateral Stiffness and Dynamic Properties of Separable Polyurethane Tires for a Folding Bike
Authors: Ryu Sarom , Ju Jaehyung , Kim Doo-Man , Kim Jin-Kyu
Published: September 2013

With an increasing demand to reduce CO2 emissions, sustainable transportation tools are drawing attention. After having reported on our initial design of a folding bike as an easy-to-carry sustainable transportation tool, we now explore lateral stiffness as well as other dynamic properties, including modal behaviors and steady state vibration characteristics. In this study, we investigate the lateral force of a separable polyurethane solid tire with varying slip and camber angles. Nonlinear hyperelastic material models are used with a commercial finite element code, ABAQUS/Standard. Transient and steady state dynamic properties of the separable bike wheel and tire are also investigated with the ABAQUS/Explicit code, and the results are compared with those of the pneumatic counterpart.
An Approach for Uni-Level Reliability Based Design Optimization Using Cross-Entropy Method
Authors: Kanakasabai Pugazhendhi , Dhingra Anoop K.
Published: September 2013

In this paper a novel approach is proposed to solve the reliability based design optimization (RBDO) problem, which is translated into a single-level problem using Karush-Kuhn-Tucker (KKT) conditions. The transformation of a bi-level RBDO problem into a single-level problem using KKT conditions introduces several equality constraints in the single-level problem definition. Presence of multiple equality constraints poses numerical difficulty to the gradient based optimizers, hence a robust algorithm to solve the single-level RBDO problem is proposed in this paper using an alternative approach. The proposed approach uses an exterior penalty based cross-entropy (CE) method to solve the uni-level RBDO problem. This approach is shown to be robust in handling equality constraints. The three example problems solved in this paper also shows that the algorithm works well with different starting points used for the design variables.
Scenario-Based Learning Environment to Support Peer-Learning
Authors: Siddique Zahed , Saha Mrinal C. , Akasheh Firas , Arif Shaiful , Barua Bipul , Hurdelbrink Keith
Published: September 2013

It is well documented that students learn more effectively when they are actively involved in the learning process, and interacting with peers. Interactive scenario-based education is a novel concept expected to stimulate active learning and provide a peer-learning experience. In this paper we present Create your Scenario Interactively (CSI) module, which is an interactive storybook-like learning tool composed of interactive storyline, 2D/3D visualization, simulation, and state-of-the-art interaction technology. The CSI method allows peer-interactions and prepares students to solve open-ended problems.

The CSI module has been developed for metal casting and implemented in manufacturing engineering courses at the University of Oklahoma and Tuskegee University. In this paper, we discuss the impact of the CSI on students’ learning in manufacturing engineering education. Our preliminary results suggest that a majority of the students feels that the CSI module is very effective in keeping them engaged. We also analyze the effect of peer-learning to develop critical thinking and solve design problems. The details of the CSI module, implementation details, and assessment results are discussed in the paper.
Perturbation Analysis and Parametric Study of Planetary Gear Vibration
Authors: Bahk Cheon-Jae , Parker Robert G.
Published: September 2013

This study analytically investigates the impact of system parameters on planetary gear vibration by using perturbation solutions. Closed-form expressions, which explicitly includes the system parameters such as contact ratio, mesh stiffness, damping, and number of planets, of the peak resonant response amplitude and parametric instability width of subharmonic resonance are obtained from perturbation analysis. System parameters related with sun-planet and ring-planet meshes show different influence on dynamic response. The effects of the system parameters are found to be sensitive to vibration modes. With use of the well-defined planetary gear modal properties, mathematical expressions of the weighting factors are derived to quantify the different sensitivity of dynamic response to the sun-planet and ring-planet meshes and to the vibration modes. The perturbation solutions are effective to examine the dependence of dynamic response on the system parameters and help one seek optimal parameters to reduce planetary gear vibration.
Guiding and Verifying Early Design Using Qualitative Simulation
Authors: Klenk Matthew , de Kleer Johan , Bobrow Daniel G. , Yoon Sungwook , Hanley John , Janssen Bill
Published: September 2013

Design of a system starts with functional requirements and expected contexts of use. Early design sketches create a topology of components that a designer expects can satisfy the requirements. The methodology described here enables a designer to test an early design qualitatively against qualitative versions of the requirements and environment. Components can be specified with qualitative relations of the output to inputs, and one can create similar qualitative models of requirements, contexts of use and the environment. No numeric parameter values need to be specified to test a design. Our qualitative approach (QRM) simulates the behavior of the design, producing an envisionment (graph of qualitative states) that represents all qualitatively distinct behaviors of the system in the context of use. In this paper, we show how the envisionment can be used to verify the reachability of required states, to identify implicit requirements that should be made explicit, and to provide guidance for detailed design. Furthermore, we illustrate the utility of qualitative simulation in the context of a topological design space exploration tool.
Configuration Workspaces of Series-Parallel Mechanisms
Authors: McCarthy Brian , Lysenko Mikola , Shapiro Vadim
Published: September 2013

The workspace of a mechanism is the set of positions and orientations that is reachable by its end effector. Workspaces have numerous applications, including motion planning, mechanism design, and manufacturing process planning, but their representation and computation is challenging due to high dimensionality and geometric/topological complexity. We propose a new formulation of the workspace computation problem for a large class of mechanisms represented by series-parallel constraint graphs. A wide variety of allowable constraints include all lower pair, some higher pair, and non-collision constraints. We show that the workspace of such mechanisms may be computed by a constraint propagation algorithm. After the space of all rigid body motions is discretized, these operations can be efficiently implemented using the Fast Fourier Transform and a depth first search. In contrast to algebraic formulations, the proposed method assures that all configurations in the computed workspace not only satisfy pairwise constraints but can be reached without breaking and reassembling the mechanism.
A Study on the Aerodynamic Drag of a Non-Pneumatic Tire
Authors: Heo Hyeonu , Ju Jaehyung , Kim Doo-Man , Rhie Sangwa
Published: September 2013

An understanding of the flow around a tire in contact with the ground is important for when designing a fuel efficient tire as aerodynamic drag accounts for about one third of an entire vehicle’s rolling loss [1]. Recently, non-pneumatic tires (NPTs) have drawn attention mainly due to their low rolling resistance associated with the use of low viscoelastic materials in their construction. However, an NPT’s fuel efficiency should be re-evaluated in terms of aerodynamic drag: discrete flexible spokes in an NPT may cause more aerodynamic drag, resulting in greater rolling resistance. In this study, the aerodynamic flow around an NPT in contact with the ground is investigated for i) stationary and ii) rotating cases using the Reynolds-Averaged Navier-Stokes (RANS) method. The NPT has a more complex flow and a higher drag force than does the pneumatic counterpart.
Structuring Senior Design Capstone to Develop Competencies
Authors: Siddique Zahed
Published: September 2013

Senior Design Capstone is a required component of many undergraduate engineering programs. The School of Aerospace and Mechanical Engineering at the University of Oklahoma has incorporated industry sponsored design projects, with Experiential Learning as the model, to develop technical and meta-competencies through the Senior Design Practicum Program. The Mechanical Engineering Capstone program has been developed to provide a learning environment, where students in teams work closely with an industry sponsor and a faculty advisor. The student teams work as a consulting group to produce useful results on an open-ended project to the sponsors’ satisfaction within the constraints of time and budget. Three major program elements, are (1) Student teams to learn and perform the tasks to achieve the desired goals of the project (2) Sponsor to define the problem, guide and accept or reject the results, and (3) Faculty to advise, coordinate, and evaluate. The Capstone program has targeted the energy industry, with a focus on oil and gas, which has a very strong presence in the region. The program, working closely with industry partners as mentors, prepares students for the energy industry. The student outcome and program are evaluated with extensive participation from industry. The program was implemented during 2002–2003. Over the last 10-years the program been able to sustain and grow. The plan that was used to sustain the program relied on developing a learning community of students, faculty and industry to support development of student competencies.
Body in White Geometry Measurements of Non-Rigid Components: A Virtual Perspective
Authors: Lindau Björn , Andersson Alf , Lindkvist Lars , Söderberg Rikard
Published: September 2013

Increased use of virtual assembly tools within automotive industry places new demands on available geometry information. Unfortunately, the measurement results of non-rigid components depend heavily on the locating schemes used in the measurement fixtures. Non-rigid component measurements are mostly performed in an over-constrained condition, describing the shapes of the parts as presented in assembly processes or as mounted on nominal products. With these kinds of measurements, there is an information loss regarding the actual springback shapes in the stored historical geometry data. Knowledge about the components’ shapes after springback is vital for virtual non-rigid fault propagation analysis.

The objective of this paper is to show the possibilities for presenting the measurement results of components as they were over-constrained, even if the parts were measured in a constrained condition (in practice limited constrained). The aim is to minimize the information loss, to spare measurement resources and to allow for better use of inspection data in assembly simulations. Predicted over-constrained measurement results in the presented cases bear reasonably good resemblance to measured over-constrained conditions when the two are compared. The ability to present both constrained and over-constrained results from one measurement setup will spare measurement resources and improve conditions for further virtual analysis and support. Furthermore, the presented cases verify the use of Method of Influence Coefficients (MIC) in the clamping step.
Revisiting the Research Field of Product-Service Systems Development
Authors: Ericson Åsa , Larsson Tobias C. , Isaksson Ola , Larsson Andreas
Published: September 2013

The research within the Product-Service Systems (PSS) field aims to support manufacturing industries’ ability to provide value in terms of a service offer to its customers, simultaneously taking a more holistic approach to eco-sustainability. The industrial idea of providing customer benefits in parallel with robust products is not new, yet equipping engineers to conduct innovation and applying a service perspective in the early design stages is noticed as fairly radical. The purpose in this paper is two-fold. First, to describe research efforts within the PSS field seen through our engineering design lenses, second, to explore and discuss plausible directions and by that identify “white spots” on the map, which may be seen as relevant directions for future research.
Computational Efficiency and Accuracy Comparison of Leaf Spring Modelling Techniques
Authors: Kat Cor-Jacques , Johrendt Jennifer L. , Els Pieter S.
Published: September 2013

Various methods exist to model leaf springs with each method having different advantages and disadvantages. Computational efficiency and accuracy are two important factors when choosing a modeling technique especially when the simulation models become large. This paper compares the computational efficiency and accuracy of an elasto-plastic leaf spring model to a neural network leaf spring model. The advantages and disadvantages of the two modeling techniques are discussed and suggestions are made for the best use of both models. It is also shown that combining the two methods can overcome some of the disadvantages and exploit the advantages of both methods. The results from the comparison quantify the accuracy and computational efficiency of the two methods giving concrete parameters for the analyst to decide on which model to use.
Effect of Waviness on Vibration and Acoustic Features of Rolling Element Bearing
Authors: Shao Yimin , Wang Pei , Chen Zaigang
Published: September 2013

Waviness of rolling element bearings, as one of the most concerned factors, would greatly influence the dynamic and acoustic performances of machines. In this paper, a new algorithm of vibro-acoustic coupling, which is based on the displacement mapping method by applying the displacement history obtained from a 6-DOF bearing dynamic model to be as the boundary condition of the finite element model of the bearing housing, is developed to predict the effect of waviness on the vibration and acoustic features of the bearing. The displacement excitation of the circumferential surface of bearing housing can be obtained by vector synthesis of bearing rigid displacement from the 6-DOF bearing dynamic model. This new method enables not only the reduction in computational cost, but also simulation of the bearing waviness under different sizes. A 6308 deep groove ball bearing model with outer race waviness is taken as an example case to examine the effectiveness of the new algorithm. The simulation results show that the new algorithm is able to predict the vibration and acoustic features of the bearing with waviness.
Modelling Uncertainty in Competitive Bidding
Authors: Kreye Melanie E. , Goh Yee Mey , Newnes Linda B.
Published: September 2013

Due to the current market development of servitisation, manufacturing companies are required to compete through the provision of services as opposed to physical products. For such companies, the shift towards being a service provider often means they have to bid for service contracts, sometimes competitively. In the context of competitive bidding, the decision makers face various influencing uncertainties. Ignoring these uncertainties or their influences can result in problems such as the generation of too little profit or even a loss or the exposure to financial risks. Raising the decision maker’s awareness of the uncertainties can provide valuable information to assist in the decision-making process. The research presented in this paper presents an approach to modeling the uncertainties at the competitive bidding stage for long-life, high-value service contracts. The aim of this research is to provide decision makers with a decision matrix which illustrates the probability of winning the service contract and the probability of making a profit. The framework utilized for identifying the uncertainties and a layered approach for analyzing these uncertainties is described. These are then applied to a case study where the modeling approaches and data gathering methods are explained and the results are displayed via the decision matrix.
Hexahedral Mesh Cutting Using Geometric Model With New Boundaries Well Matched
Authors: Zhu Hua , Gao Shuming , Xian Chuhua
Published: September 2013

Hexahedral mesh generation is difficult and time-consuming. To avoid the complicated hexahedral mesh regeneration after each variational design, hexahedral mesh editing can be used. In this paper, an accurate hexahedral mesh cutting approach using geometric model is proposed, and the part of the geometric model inside the mesh model can be complex and arbitrary. In the approach, all the newly added geometric entities resulted from mesh cutting are first generated by performing the subtraction operation between the mesh model and the geometric model. Then, for each newly added geometric element, including point, edge and face, the mesh nodes that need to be moved onto it, are determined and repositioned with the mesh quality considered. To ensure the rationality of mesh nodes determination, for each newly added edge, the mesh nodes are identified using shortest path algorithm. Finally, the mesh elements that should not be in the resultant mesh model are deleted, Pillowing and Smoothing operations are further conducted to improve the mesh quality. Some preliminary results are given to show the feasibility of the approach.
The Kinematic Synthesis of a Robust RCCC Mechanism for Pick-and-Place Operations
Authors: Al-Widyan Khalid M. , Angeles Jorge
Published: September 2013

Proposed in this paper is a methodology to synthesize a RCCC four-bar linkage intended for pick-and-place operations. The synthesis problem is set in the context of rigid-body guidance, which can be solved exactly for up to four prescribed poses of the coupler link. As a consequence, for a pick-and-place operation, the selection of the unspecified two intermediate poses is thus left up to the mechanism designer’s judgment. In this paper, we propose a method to determine the two intermediate poses resorting to the concept of robustness. In fact, robustness is needed in this context to overcome the presence of uncertainty due to the selection of the two unspecified poses. To this end, a theoretical framework for model-based robust design is invoked and a general methodology for robust kinematic synthesis is laid down. A numerical example is included to validate the concepts and illustrate the application of the methodology proposed here.
Development of the Next-Generation Computational Fracture Mechanics Simulator on the Earth Simulator 2
Authors: Yodo Kaworu , Kawai Hiroshi , Okada Hiroshi , Ogino Masao , Shioya Ryuji
Published: September 2013

Fracture mechanics analysis using the finite element method has been one of the key methodologies to evaluate structural integrity for aging infrastructures such as aircraft, ship, power plants, etc. However, three-dimensional crack analyses for structures with highly complex three-dimensional shapes have not widely been used, because of many technical difficulties such as the lack of enough computational power.

The authors have been developing a fracture mechanics analysis system that can deal with arbitrary shaped cracks in three-dimensional structures. The system consists of mesh generation software, a finite element analysis program and a fracture mechanics module. In our system, a Virtual Crack Closure-Integral Method (VCCM) for the quadratic tetrahedral finite elements is adopted to evaluate the stress intensity factors. This system can perform the three-dimensional fracture analyses. Fatigue and SCC crack propagation analyses with more than one cracks of arbitrary complicated shapes and orientations. The rate and direction of crack propagation are predicted by using appropriate formulae based on the stress intensity factors.

When the fracture mechanics analysis system is applied to the complex shaped aging structures with the cracks which are modeled explicitly, the size of finite element analysis tends to be very large. Therefore, a large scale parallel structural analysis code is required. We also have been developing an open-source CAE system, ADVENTURE. It is based on the hierarchical domain decomposition method (HDDM) with the balancing domain decomposition (BDD) pre-conditioner. A general-purpose parallel structural analysis solver, ADVENTURE_Solid is one of the solver modules of the ADVENTURE system.

In this paper, we combined VCCM for the tetrahedral finite element with ADVENTURE system and large-scale fracture analyses are fully automated. They are performed using the massively parallel super computer ES2 (Earth Simulator 2) which is owned and run by JAMSTEC (Japan Agency for Marine-Earth Science and Technology).
Synthesis and Construction of a Family of One-DOF Highly Overconstrained Deployable Polyhedral Mechanisms (DPMs)
Authors: Wei Guowu , Dai Jian
Published: September 2013

This paper presents a family of one-DOF highly overconstrained regular and semi-regular deployable polyhedral mechanisms (DPMs) that perform radially reciprocating motion. Based on two fundamental kinematic chains with radially reciprocating motion, i.e. the PRRP chain and a novel plane/semi-plane-symmetric spatial eight-bar linkage, two methods, i.e. the virtual-axis-based (VAB) method and the virtual-centre-based (VCB) method are proposed for the synthesis of the family of regular and semi-regular DPMs. Procedure and principle for synthesizing the mechanisms are presented and selected DPMs are constructed based on the five regular Platonic polyhedrons and the semi-regular Archimedean polyhedrons, Prism polyhedrons and Johnson polyhedrons. Mobility of the mechanisms is then analysed and verified using screw-loop equation method and degree of overconstraint of the mechanisms are investigated by combing the Euler’s formula for polyhedrons and the Grübler-Kutzbach formula for mobility analysis of linkages.
The Function Analysis Diagram
Authors: Aurisicchio Marco , Bracewell Rob , Armstrong Gareth
Published: September 2013

Understanding product functions is a key aspect of the work undertaken by engineers involved in complex system design. The support offered to these engineers by existing modeling tools such as the Function Tree and the Function Structure is limited as they are not intuitive and do not scale well to deal with real world engineering problems. A research collaboration between two universities and a major power system company in the aerospace domain has allowed the authors to further develop a method for function analysis known as Function Analysis Diagram (FAD) which was already in use by line engineers. The capability to generate and edit these diagrams was implemented in the Decision Rationale editor (DRed) a software tool for capturing design rationale. This article presents the main beneficial characteristics of the method and justifies them using two engineering case studies. The results of the research have shown that the FAD method has a simple notation, permits the modeling of product functions together with structure, allows the production of rich and accurate descriptions of product functionality and is suitable to represent complex problems.
Test Rig for Extraction of the Contact Parameters for Plane on Plane Contact
Authors: Botto D. , Lavella M. , Gola M. M.
Published: September 2013

The modelling of the friction interfaces has received much attention in recent years from the aerospace industry. In order to obtain reliable prediction of the nonlinear dynamic behaviour of the disc and blades in the aerospace engine the friction forces at interfaces, such as in under-platform dampers, blade and fir tree roots or shrouds, must be modelled accurately. Two contact parameters, namely the contact stiffness and the coefficient of friction, are sufficient to model, with good accuracy, the friction contact. The contact parameters are obtained experimentally, and are of interest for the designer only if representative of the operational environment of the engine. To pursue this aim a test rig has been designed to perform experiments in a wide range of temperatures, with different combinations of normal and tangential load, frequencies and mating materials, representative of the real operating condition of the engine. Most of the rigs found in literature perform most likely point contact even if the two bodies have plane mating surfaces. The design of a real plane-on-plane contact test rig is not an easy task but despite the difficulty a solution was found in the design shown in this work. The core of the rig is a tilting mechanism enabling one surface to lies down on the other so that the plane-on-plane contact is achieved, at least within the flatness geometrical tolerance of the surfaces. The results of the experiments are the hysteresis loops, namely the tangential contact force against the relative displacement, from which the contact parameters can be calculated. Measurements of displacements are taken very close to the actual contact area and are performed by means of two laser interferometers. Localized heating is achieved by means of an induction heating machine while a thermocouple measures the temperature at points close to the contact area.