bluuebunny/crossref_metadata_2025 huggingface dataset:
A Review of Methods for Design Under Uncertainty From the Perspective of Utility Theory
Authors: Lee Benjamin D. , Thompson Stephanie C. , Paredis Christiaan J. J.
Published: March 2011

In this paper, we present a review of methods for design under uncertainty. Specifically, we examine Reliability-Based Design, Robust Design, and Risk-Informed Design from the perspective of utility theory. Although these methods account for uncertainty, they differ from utility theory in that they limit the types of preferences that can be expressed. Limitations on the types of preferences that can be expressed can be valuable to designers because they reduce the effort required to elicit preference. However, the value of these methods for a particular design scenario depends greatly on the appropriateness of the preference model they implicitly impose. As such, they should be used with caution; they should not be applied when the associated preference models are not reasonable approximations of the designer’s true preferences. To help designers decide when the methods are appropriate, we identify the preference models by formulating the methods in a common framework of utility theory. The methods are then critically examined and compared based on their costs and the value they add to the design process.
State Transition in Reconfigurable Systems
Authors: Chmarra Magdalena K. , Verriet Jacques , Waarsing Rene´ , Tomiyama Tetsuo
Published: March 2011

Reconfigurable systems that maintain a high level of performance under changing operational conditions and requirements are an ongoing research challenge. Many existing systems are able to work under narrow operational conditions only. They should perform the configuration transitions from the current state to a desired one smoothly. The question is: how to find the optimal state transition trajectory that configures the system from an initial state to a desired state? We present a method to determine steps (list of actions to be taken) of state transitions for reconfigurable systems. This method makes use of graph search algorithms that solve shortest path problems and that are commonly used in routing: Dijkstra’s algorithm and the A* algorithm. The method is applied to the design of a reconfigurable printer, which has to change its configuration to achieve maximum performance (e.g. high quality of print) when operational conditions are changing (e.g. speed of printing).
Bayesian Network Classifiers for Set-Based Collaborative Design
Authors: Shahan David , Seepersad Carolyn C.
Published: March 2011

Complex design problems are typically decomposed into smaller design problems that are solved by domain-specific experts who must then coordinate their solutions into a satisfactory system-wide solution. In set-based collaborative design, collaborating engineers coordinate themselves by communicating multiple design alternatives at each step of the design process. The goal in set-based collaborative design is to spend additional resources exploring multiple options in the early stages of the design process, in exchange for less iteration in the latter stages, when iterative rework tends to be most expensive. Several methods have been proposed for representing sets of designs, including intervals, surrogate models, fuzzy membership functions, and probability distributions. In this paper, we introduce the use of Bayesian networks for capturing sets of promising designs, thereby classifying the design space into satisfactory and unsatisfactory regions. The method is compared to intervals in terms of its capacity to accurately classify satisfactory design regions as a function of the number of available data points. A simplified, multilevel design problem for an unmanned aerial vehicle is presented as the motivating example.
Analysis of a New Form of Intrinsically Automatic Continuously Variable Transmission
Authors: Cyders Timothy , Williams Robert L.
Published: March 2011

Effective continuously variable transmission (CVT) designs have been sought after for many years as their integration into many different mechanical systems can give many advantages over a discrete transmission system. Currently, CVTs are becoming popular for applications from automotive power transmission to wind power generation. Most CVT technologies, however, are friction- or hydraulic-based designs limited by both performance and system characteristics. This paper will evaluate a new, patented form of purely mechanical, intrinsically automatic CVT which is not based on belts, pulleys, gears or hydraulics. This new transmission is based on a deformable four-bar design incorporating a one-way clutch for positive displacement of the output. As torque demand on the system output is varied, the output’s displacement varies inversely to maintain a constant peak torque on the input shaft. The end result of this behavior is a possible instantaneous variation of speed ratio over an extreme range with a lightweight, simple mechanical design. This paper provides an analysis of the mechanism and its performance, as well as simulation results incorporating real-world measurement of system output into several different mechanical applications: a human-powered vehicle, an automobile and a centrifugal pump.
A Study of the Effect of Geometry Changes on the Structural Stiffness of a Composite D-Spar
Authors: Visweswaraiah Swaroop B. , Pasini Damiano , Lessard Larry
Published: March 2011

The paper examines the impact of varying two geometric cross-section parameters of an advance composite D-spar on its structural stiffness. For a given blade topology, the orientation of the D-spar web with respect to the beam axis and the distance of the D-spar web from the leading edge of the blade have been selected here as the variables of study, as they govern the elastic properties of the composite cross-section. A code has been developed to calculate the matrix terms of the Euler-Bernoulli cross-sectional stiffness utilizing the closed form expressions of the structural properties formulated by assuming both Thin-Walled composite Beam theory (TWB) and Classical Laminate Theory. The code has been validated through the Variational Asymptotic Beam Sectional analysis (VABS) for the cross-sectional stiffness matrix. Two cases have been studied for a quasi-isotropic laminate D-spar. The first is for a symmetric airfoil, whereas the second is for an unsymmetrical airfoil. The variation of the stiffness parameters for the quasi-isotropic D-spar including the coupling parameters has been visualized into parametric maps. The paper also examines the impact that these geometric variables have on the stiffness-to-mass ratio to show that along with the ply orientations they play a major role in the aeroelastic tailoring and structural optimization of a composite blade.
Analysis of a Planar Tensegrity-Based Compliant Mechanism
Authors: Moon Youngjin , Crane Carl D. , Roberts Rodney G.
Published: March 2011

This paper presents an analysis of a planar tensegrity-based mechanism. In this study, a moving body is joined to ground by four compliant leg connectors. Each leg connector is comprised of a spring in series with an adjustable length piston. Two problems are solved in this paper. In the first, the values of the four spring constants and free lengths are given and the lengths of the four pistons are determined such that: (1) the top body is positioned and oriented at a desired pose; (2) the top body is at equilibrium while a specified external wrench is applied; and (3) the total potential energy stored in the four springs equals some desired value. In the second problem, the values for the four spring free lengths are given and the values for the four spring constants and the lengths of the four pistons are determined such that conditions (1) and (2) from above are met and also the instantaneous stiffness matrix of the top body equals a specified set of matrix values. The paper formulates the solutions of these two problems. Numerical examples are presented.
Loading Subspace Selection for Multidimensional Characterization Tests via Computational Experiments
Authors: Iliopoulos A. P. , Michopoulos J. G.
Published: March 2011

To pursue characterization of composite materials, contemporary automated material testing machines are programmed to follow loading paths in multidimensional spaces. A computational methodology for selecting the best loading subspace among all those possible is formulated and presented in this paper. The criterion for subspace selection employed is based on the assessment of which among the possible subspaces generates the richest set of strain-states as compared to those of the union of all possible 4D loading spaces. A systematic program of simulation sequences of virtual experiments is presented and the concept of strain state cloud (SSC) is introduced as a high dimensional volumetric histogram describing the frequency of appearance of each strain state within the corresponding strain space. Comparison of the SSCs for each of the fifteen 4D subspaces relative to the full 6D space allows a ranking classification of each subspace. Based on this ranking we select the three top cases as being those considered for actual testing.
Comparative Study of Turning Performance Between a Vehicle With Planar Suspension Systems and a Conventional Vehicle
Authors: Zhu Jian Jun , Khajepour Amir , Esmailzadeh Ebrahim
Published: March 2011

In a conventional vehicle, the vibration caused by road obstacles can not be effectively isolated in the longitudinal direction due to the fact that the longitudinal connections between the chassis and wheels are typically very stiff compared with the vertical connections. To overcome this limitation, a novel concept design of a planar suspension system (PSS) is proposed. The rather stiff longitudinal linkages are replaced by elastic ones in a PSS so that the vibration along any direction in the wheel plane can be effectively isolated. The soft longitudinal connection can change the wheelbase and the vehicle’s weight distribution at the front and rear wheels, and may further change the handling performance. This paper presents a comparative study of the handling behaviour of a PSS vehicle and a similar conventional vehicle in cases of a combining operation between a turning and acceleration, and a turning on a road with pothole. The study demonstrates that the PSS vehicle has the potential to absorb the vibration in the longitudinal direction without sacrificing the handling performance. The handling behaviour of a PSS vehicle is generally comparable with, and under some conditions, even better than that of a conventional vehicle.
An Extended Pattern Search Approach to Wind Farm Layout Optimization
Authors: Du Pont Bryony L. , Cagan Jonathan
Published: March 2011

An extended pattern search approach is presented for optimizing the placement of wind turbines on a wind farm. The algorithm will develop a two-dimensional layout for a given number of turbines, employing an objective function that minimizes costs while maximizing the total power production of the farm. The farm cost is developed using an established simplified model that is a function of the number of turbines. The power development of the farm is estimated using an established simplified wake model, which accounts for the aerodynamic effects of turbine blades on downstream wind speed, to which the power output is directly proportional. The interaction of the turbulent wakes developed by turbines in close proximity largely determines the power capability of the farm. As pattern search algorithms are deterministic, multiple extensions are presented to aid escaping local optima by infusing stochastic characteristics into the algorithm. This stochasticity improves the algorithm’s performance, yielding better results than purely deterministic search methods. Three test cases are presented: a) constant, unidirectional wind, b) constant, multidirectional wind, and c) varying, multidirectional wind. Resulting layouts developed by this extended pattern search algorithm develop more power than previously explored algorithms with the same evaluation models and objective functions. In addition, the algorithm’s layouts motivate a heuristic that yields the best layouts found to date.
Evaluation of Contact Force and Elastic Foundation Models for Wear Analysis of Multibody Systems
Authors: Mukras Saad M. , Kim Nam Ho , Schmitz Tony L. , Sawyer W. Gregory
Published: March 2011

In this paper, two procedures to analyze planar multibody systems experiencing wear at a revolute joint are compared. In both procedures, the revolute joint of interest includes a clearance whose shape and size are dictated by wear. The procedures consist of coupled iterative analyses between a dynamic analysis of the system with non-ideal joints and wear prediction to determine the evolution of the joint clearance. In the first procedure, joint forces and contact pressure are estimated using the elastic foundation model (EFM) with hysteresis damping via the dynamic analysis. In the second procedure, a contact force model with hysteresis damping is used to estimate the joint forces. In the latter case, however, the contact pressure is estimated using a finite element method (FEM). Comparison in performance of the two models is facilitated through the use of an experimental slider-crank mechanism in which wear is permitted to occur at one of the joints. It is observed that the two procedures provide similar estimates for the dynamics response and wear volumes but substantially different predictions on the wear profiles. Additionally, experimental results show that while predictions on the wear volume from both models are reasonably accurate, the FEM-based model produced more accurate predictions on the wear profile.
How Does Modularity Affect Green Design?
Authors: Durand James , Telenko Cassandra , Seepersad Carolyn
Published: March 2011

Product architecture significantly influences environmental impact. Modular architectures aid manufacture and reuse, thereby reducing manufacturing-related impacts and diverting usable waste from landfills. In contrast, modular product architectures may also sacrifice product performance or lead to over-designed products. These side-effects can increase environmental impact. The Black and Decker Firestorm and G5 George Foreman Griddle were studied to uncover and understand the effects of product architecture on energy and material efficiency. Both products incorporate component sharing for fulfilling multiple functions and incur environmental tradeoffs as a result. Experimentation, reverse engineering, and life cycle analysis of these products were used to inspire a number of guidelines for green design of modular product architectures. Difficulties involved the design of interfaces and selection of components for shared modules.
Effect of Material Stiffness on Intermodulation Response in Dynamic Atomic Force Microscopy
Authors: Platz Daniel , Forchheimer Daniel , Thole´n Erik A. , Hutter Carsten , Haviland David B.
Published: March 2011

We perform simulations and experiments on an oscillating atomic force microscope cantilever approaching a surface, where the intermodulation response of the cantilever driven with two pure harmonic tones is investigated. In the simulations, the tip and surface interact with a conservative nonlinear force, and the parameter space of approach distance and surface stiffness is explored. Approach experiments are carried out on three surfaces with widely varying stiffness. Qualitative similarities between simulations and experiment can be seen, but quantitative comparison is difficult due to the overly idealized tip-surface force model used in the simulation.
MTConnect-Based Kaizen for Machine Tool Processes
Authors: Lee B. E. , Michaloski J. , Proctor F. , Venkatesh S. , Bengtsson N.
Published: March 2011

Kaizen is a part of Lean Manufacturing that focuses on the concept of continuous improvement to reduce waste. For implementing Kaizen on the factory floor, comprehensive and efficient tools for data acquisition, process measurement and analysis are required. The MTConnect open specification provides for cost-effective data acquisition on the manufacturing floor for machine tools and related devices. This paper will look at a Kaizen implementation on the shop floor level for continuous improvement using real-time MTConnect data. The Kaizen transformation of machine data into production knowledge was performed in order to understand energy consumption, asset operation and process performance. The paper takes a detailed examination of the machine tool energy management.
Multiscale Modeling of Ductile Iron Solidification With Continuous Nucleation by a Cellular Automaton
Authors: Burbelko Andriy A. , Gurgul Daniel , Fras´ Edward , Guzik Edward
Published: March 2011

The solidification of metals and alloys is a typical example of multiphysics and multiscale engineering systems. The phenomenon of different time and spatial scales should be taken into consideration in the modeling of a microstructure formation: heat diffusion, the components diffusion in the liquid and solid phases, the thermodynamics of phase transformation under a condition of inhomogeneous chemical composition of growing and vanishing phases, phase interface kinetics, and grains nucleation. The results of a two-dimensional modeling of the microstructure formation in a ductile cast iron are presented. The cellular automaton model (CA) was used for the simulation. The model takes into account the nucleation of two kinds of grains that appear inside of the liquid during solidification: austenite and graphite. The six states of CA cells correspond to the above-mentioned three phases (liquid, austenite and graphite) and to the three two-phase interfaces. A numerical solution was used for the modeling of concentration and temperature fields. The parabolic nonlinear differential equations with a source function were solved by using the finite element method and explicit scheme. In the mono-phase cells the source function is equal to zero. In the interface cells the value of the source function varies depending on the local undercooling. The undercooling value depends on the front curvature, the local temperature and the local chemical composition of the phases. Overlapping lattices with the same spatial step were used for concentration field modeling and for the CA. The time scale of the temperature field for this lattice is about 104 times shorter. Due to the above reasons, another lattice was used with a multiple spatial step and the same time step. The new grain nucleation of solid phases from a liquid is a phenomenon which must be taken into account for correct simulation of a polycrystalline structure formation. The cumulative distribution curve approach was used to calculate the number of substrates on which nucleation takes place as a function of under-cooling below the equilibrium temperature. An algorithm of continuous nucleation modeling during solidification is presented. The undercooling of solid phase grain nucleation was calculated on the basis of the inverse function of the above-mentioned cumulative distribution curve (fractile) with the argument equal to the random number generated in the interval 0…1 with uniform density. The domain of correct usage of this algorithm was analyzed.
Exploring Automatically Generated Design Concepts Using Cyberinfrastructure
Authors: Naim Aziz M. , English Kenneth W. , Lewis Kemper E.
Published: March 2011

Our society has witnessed major growth and innovation in technology. However, one of innovation’s fundamental aspects, designer creativity, is still largely unsupported by information technology (IT) tools. This paper establishes a bridge between efforts to use cyberinfrastructure to generate design alternatives and a designer’s ability to explore and evaluate concepts. The research presented provides a method of synthesizing a web-based representation of a product concept using information from a digital design repository, an automatic concept generator, and results from a clustering analysis. A visualization interface is developed to provide designers with multiple representations of product concepts. The development of this approach establishes a computing infrastructure to support an investigation into the effect of information technology on designer creativity and provides a foundation for the development of further support technology. The architecture is implemented and the result is illustrated with an example in order to show the capabilities of the approach.
A Simulation-Based Robust Concept Exploration Method
Authors: Rippel Markus , Choi Seung-Kyum , Mistree Farrokh , Allen Janet K.
Published: March 2011

In early stages of the engineering design process it is necessary to explore the design space to find a feasible range or point that satisfies the design requirements. When robustness of the system is among the requirements, the Robust Concept Exploration Method (RCEM) can be used. In RCEM a metamodel such as a global response surface of the entire design space is used. Based on this surrogate model the robustness of the system is evaluated. In nonlinear or multimodal design spaces a very detailed metamodel such as a very high order response surface might be required to reflect accurately the characteristics of the model. For large design spaces this is computationally very expensive. In this paper, using the Probabilistic Collocation Method (PCM) for generating local response models at the points of interest, a Simulation-Based RCEM is proposed as a very efficient and flexible robust concept exploration method. We believe that using the PCM with other design exploration methods would be equally effective.
Preliminary In Vivo Capsule Crawler Mobility
Authors: Sliker Levin J. , Schoen Jonathan A. , Rentschler Mark E.
Published: March 2011

Despite revolutionary advances in many fields of medicine, there are no active mobile in vivo devices commercially available, or in use, today. Several research groups are actively looking at a number of mobility methods in a number of lumens, but little commercial work has been done. While robotic surgery is available today thanks to robots such as the da Vinci surgical system, these methods are very expensive, require heavy external equipment, and are still constrained by entry incisions. An alternative approach may be to place the robot completely inside the patient. Such devices may enable non-invasive imaging and diagnostics. These devices may be significantly less expensive than current minimally invasive methods, without extensive support equipment, which may allow them to be also used routinely in the ER/trauma sites and remote locations. This paper explores using mobile capsule crawlers inside the body. Preliminary designs are discussed, and current research efforts into providing contact locomotion using micro-tread tracks are explored including initial drawbar force generation experimental results.
Form Follows Form: Fine Tuning Artificial Intelligence Methods
Authors: Bohm Matt R. , Stone Robert B.
Published: March 2011

This paper presents an updated approach to a form-based concept generation technique known as Form Follows Form (FFF). The technique allows a novice engineer or designer to use natural language to specify components envisioned within a product. Form follows form then develops the underlying functional structure by leveraging a repository of over 5500 artifacts. Existing computational conceptual design methods are then employed to automatically display a set of ranked concept alternatives to the user. Users can quickly create a functional model by specifying input components and answering questions regarding the intent of the product. In this paper we demonstrate the capabilities of the Form Follows Form method through a case study involving the redesign of a standard household fan. Through the case study it is shown that FFF is capable of suggesting creative alternatives for existing products. Additionally, we present data regarding the accuracy and usefulness of FFF gathered through a junior level design course at Oregon State University.
Automated Concept Generation Using Branched Functional Models
Authors: Choudhary Abhinav Krishna , Bryant Arnold Cari
Published: March 2011

This paper discusses a new concept generation technique that improves upon a previous automated concept generation theory and algorithm developed by Bryant, et al. at the University of Missouri – Rolla. The previous automated concept generation algorithm utilizes the design knowledge present in a repository to produce an array of partial concept solutions. While the previous algorithm is capable of handling branched functional models, it does not efficiently remove all of the infeasible partial solutions to leave only whole concepts in the final results. A matrix-based algorithm is presented in this paper that utilizes the result from the previous concept generation algorithm and solves for complete solutions of branched concepts. The presented algorithm eliminates incomplete and infeasible concepts or components from the results and generates a set of full solutions for further analysis by a designer. The details of the algorithm are described in this paper, and a peanut-sheller example is used to illustrate the effective use of the algorithm for producing branched concept variants.
High-Performance Heat Sink for Hybrid Electric Vehicle Inverters
Authors: Vetrovec John
Published: March 2011

We report a novel active heat sink (AHS) that allows high-density electronic components to operate at a stable temperature over a broad range of ambient conditions. AHS receives heat at high flux and transfers it at reduced flux to environment, coolant fluid (e.g., air or engine coolant), heat pipe, or structures. Temperature of the heat load can be controlled electronically. Target applications for AHS include thermal management of high-power inverters for hybrid electric vehicles. Depending on the configuration, AHS can handle a heat load of several hundred watts at a heat flux over 1,000 W/cm2 with a thermal resistance as low as 0.1 °C/W. AHS physics, engineering design for inverter applications, performance simulations, and initial test data are presented.
Application of Piezoelectric and Functionally Graded Materials in Designing Electrostatically Actuated Micro Switches
Authors: Hosseinzadeh A. , Ahmadian M. T.
Published: March 2011

In this research, a functionally graded microbeam bonded with piezoelectric layers is analyzed under electric force. Static and dynamic instability due to the electric actuation is studied because of its importance in micro electro mechanical systems, especially in micro switches. In order to prevent pull-in instability, two piezoelectric layers are used as sensor and actuator. A current amplifier is used to supply input voltage of the actuator from the output of the sensor layer. Using Hamilton’s principle and Euler-Bernoulli theory, equation of motion of the system is obtained. It is shown that the load type (distributed or concentrated) applied to the microbeam from the piezoelectric layer, depends on the shape of the actuator layer (E.g. rectangle, triangular…). Finite element method is implemented for evaluation of displacement field in the microbeam and Dynamic response of the microbeam under electric force is calculated using finite difference method. Effect of squeeze film damping on pull-in voltage and time-response of the system is considered using nonlinear Reynolds equation. Effect of several parameters such as gain value between piezoelectric sensor and actuator layer, profile of functionally material, and geometry of the system is considered on dynamic behavior of the micro beam especially on pull-in instability. Results are verified for simple cases with previous related studies in the literature and good agreements were achieved. Results found indicate that increasing gain value between sensor and actuator, enhances stiffness of the system and will raise pull-in voltage. Also, dependency of dynamic properties of the system such as amplitude and frequency of vibration on functionally graded material profile is shown. The material distribution of the functionally graded material is designed in such a way that results in a specific pull-in voltage.
A Fast Grid Deformation Algorithm for Aerodynamic Shape Optimization
Authors: Mohamed Kaveh , Sermeus Kurt , Laurendeau Eric
Published: March 2011

A mesh movement algorithm suitable for aerodynamic design optimization problems is presented. It involves B-spline surface construction, projection and evaluation on B-spline faces for the surface mesh movement, as well as inverse-distance and 2D/3D TFI interpolations for the volume mesh deformation. The algorithm is fast and exhibits an excellent parallel efficiency. It is used to deform the surface and volume mesh of an ONERA-M6 wing undergoing several planform changes. The quality of the deformed mesh is preserved as long as the difference between the initial surface mesh and the B-spline surface model is small. A good agreement reported between the flow simulation results on the deformed mesh and those obtained on initial fixed mesh.
The Search for Innovation Styles
Authors: Nix Anthony A. , Stone Robert B.
Published: March 2011

The Myers-Briggs Type Indicator test is known to be a quick and easy way to build good team dynamics. However the workplace is not always built around four person teams that you can easily change based on individual personalities. Research has shown that the various MBTI personalities associate with different learning styles. This gives reason to believe that different individual designers may synthesize data and conceptualize ideas differently in a design environment. If this is true, designers may need a customizable environment or they may need to explore different ways to achieve their potential. This paper examines how individuals with different MBTI personality types take in and view information during the conceptualization stages of product design and whether the way information is inputed is vital to an innovative product design.
A New Kind of Energy Transfer From the High-Frequency to Low-Frequency Mode in a Composite Laminated Plate
Authors: Zhang Wei , Guo Xiang-Ying , Wang Qian , Liu Cui-Cui , He Yun-cheng
Published: March 2011

This paper focuses on the analysis on a new kind of nonlinear resonant motion with the low-frequency large-amplitude, which can be induced by the high-frequency small-amplitude mode through the mechanism of modulation of amplitude and phase. The system investigated is a simply supported symmetric cross-ply composite laminated rectangular thin plate subjected to parametric excitations. Experimental research has been carried out for the first time. The test plate was excited near the first natural frequency with parametric forces and the above mentioned high-to-low frequency mode has been observed, whose frequency is extremely lower than the first natural frequency. Theoretical job goes to analysis the above phenomenon accordingly. Based on the Reddy’s third-order shear deformation plate theory and the von Karman type equation, the nonlinear governing equations of the simply supported symmetric cross-ply composite laminated rectangular thin plate subjected to parametric excitations are formulated. The Galerkin method is utilized to discretize the governing partial differential equations into a two-degree-of-freedom nonlinear system. Numerical simulation is conducted to investigate this non-autonomous system subsequently. The results of numerical simulation demonstrate that there is a qualitative agreement between the experimental observation and the theoretical result. Besides, the multi-pulse chaotic motions are also reported in numerical simulations.
Type Synthesis Principle and Practice of Flexure Systems in the Framework of Screw Theory: Part II—Numerations and Synthesis of Complex Flexible Joints
Authors: Yu J. J. , Pei X. , Li S. Z. , Su Hai-jun , Hopkins J. B. , Culpepper M. L.
Published: March 2011

In recent years, the increasing of application requirements call for development of a variety of high-performance (e.g. large-displacement, high-precision) flexible joints. In this paper we demonstrate how to use the proposed methodology for the type synthesis of flexure systems given in the companion paper to synthesize concepts for complex flexible joints. According to the joint characteristics other than other flexure systems, a basic design philosophy and a general type synthesis process for flexible joints are presented firstly. The numerations and type synthesis for four commonly used flexible joint types, i.e. flexible revolute joints (FRJs), flexible translational joints (FTJs), flexible universal joints (FUJs), and flexible spherical joints (FSJs) are investigated in detail. As a result, not only a variety of known flexible joints are systematically surveyed and classified, but also are some new flexible joints developed. The output of this process is the derivation of a multiple of flexible joint concepts that would then be modeled and optimized by existing modeling and analysis methods.
Mitigating E-Waste: A Product Service System (PSS) Based Design Approach to Create Obsolescence Resistant Products
Authors: Rai Rahul , Tekunoff Uriel , Schafer Carson , Sandborn Peter , Terpenny Janis
Published: March 2011

Consumers of electronic products (e-products) increasingly purchase new product and dispose of the last-generation of fully functional product for the sake of newer models with added functionality brought on by advances in technology. This consumer behavior is referred to as technological obsolescence, rendering older versions of the product obsolete and creating e-waste. The phenomenon of technological product obsolescence and e-waste is especially prevalent in electronic products such as cell phones and video games. E-waste is very costly for the environment, as well as for electronics product manufacturers. This paper investigates the use of a Product Service System (PSS) based model to design obsolescence resistance product, hence mitigating the impact of e-waste. The approach is derived from the results of an empirical study of multiple high e-waste generating products. As part of the study, various products are analyzed and guidelines for designs are derived from the empirical data. The utility of the proposed approach is demonstrated via the conceptual design of a novel smart phone based on the PSS framework.
A New Variable Stiffness Spring Using a Prestressed Mechanism
Authors: Azadi Mojtaba , Behzadipour Saeed , Guest Simon
Published: March 2011

A novel design of a semi-active variable stiffness element is proposed, with possible applications in vibration isolation. Semi-active vibration isolators usually use variable dampers. However, it is known from the fundamental vibration theory that a variable spring can be far more effective in shifting the frequencies of the system and providing isolation. Geometry change is a common technique for building variable springs, but has disadvantages due to the complexity of the required mechanism, and slow response due to the inertia of moving parts. In the variable spring introduced here (VS), the stiffness is changed by force control in the links which corresponds to infinitesimal movements of the links, and does not need a change of geometry to provide a change of stiffness. This facilitates a fast response. The proposed VS is a simple prestressed cable mechanism with an infinitesimal mechanism. Theoretically the level of the prestress in the cables can be used to control the stiffness from zero to a maximum value that is only limited by the strength of the links. In this work, the statics, kinematics and stability of the VS are studied, the stiffness is formulated, and possible configurations of the VS are found.
Apparent Mass Responses of Seated Occupants Under Single and Dual (XZ) Axis Vibration
Authors: Mandapuram S. , Rakheja S. , Boileau P.-E. , Maeda S.
Published: March 2011

This study investigated the biodynamic responses of the seated body to two-axis vibration applied along the fore-aft and vertical directions in the 0.5 to 20 Hz range, independently and simultaneously, using 9 adult male subjects. The measurements were performed with the subjects seated with and without the hands and back supports under two different magnitudes of vibration. The apparent mass responses distributed over the seat pan and the back support are determined in order to better understand the dynamic interactions of the body with the back support under single as well as dual-axis vibration. The results suggest strong influences of the back and hand supports, and considerable cross-axis apparent mass along the vertical axis. Only minimal coupling effects of dual axis vibration, however, could be observed, although coupled sagittal plane motions were perceived by the subjects. Using the linear system theory, the total response along each axis was also computed from the direct and cross-axis responses to individual axes vibration, which emphasized contributions due to cross-axis response and thus the coupling effects of multi-axis vibration.
Study of Existing Metrics Used in Measurement of Ideation Effectiveness
Authors: Srivathsavai Ramesh , Genco Nicole , Ho¨ltta¨-Otto Katja , Seepersad Carolyn C.
Published: March 2011

In recent years, many new idea generation methods have been developed to generate innovative concepts. The effectiveness of those methods is evaluated by applying a set of metrics to the resulting concepts. Several metrics have been proposed for this purpose, including quality, novelty, and variety metrics, but the inter-rater reliability of those metrics has not been investigated extensively. In this paper, the inter-rater reliability of three existing metrics is analyzed by applying them to the results of a representative idea generation study. The effects on inter-rater agreement of analyzing concepts at the overall concept level versus the feature level are investigated, along with the impacts of alternative scales for specific metrics. In general, the inter-rater reliability of the metrics is found to be relatively low, with the most reliable results obtained at the feature level. The use of different scales also affects inter-rater reliability, but the effect is less significant. In addition to their low levels of repeatability, the metrics differ in how novelty is appraised.
Enriching Assembly CAD Models With Functional and Mechanical Informations to Ease CAE
Authors: Foucault Gilles , Le´on Jean-Claude
Published: March 2011

Assembly models can be regarded as a kernel for product development processes where they can efficiently contribute to many product simulation behaviors. Assembly models are often containing 3D B-Rep CAD models, possibly with geometric constraints between the components and bill of materials. However, these models are often difficult to process for simulations because algorithms often face a very large diversity of configurations. One origin of such difficulties can be found in companies’ practice where components may be represented differently from one company to another and their interfaces as well. In any case, interfaces between components are not explicit, which leads to tedious model processing tasks. This paper illustrates preparation of assembly models to ease CAE through an analysis of company practices, showing that a concept of conventional representations is an important starting point to efficient treatments of assemblies. In addition, it is described how interfaces and conventional representations can be combined to derive functional and mechanical information from geometric models of components. Illustrations of the proposed approach is given throughout the paper using various standard components.
Load-Transmitter Constraint Sets: Part I—An Effective Tool for Visualizing Load Flow in Compliant Mechanisms and Structures
Authors: Krishnan Girish , Kim Charles , Kota Sridhar
Published: March 2011

Visualizing load flow aids in conceptual design synthesis of machine components. In this paper, we present a mathematical framework to visualize load flow in compliant mechanisms and structures. This framework uses the concept of transferred forces to quantify load flow from input to the output of a compliant mechanism. The key contribution of this paper is the identification a fundamental building block known as the Load-Transmitter Constraint (LTC) set, which enables load flow in a particular direction. The transferred force in each LTC set is shown to be independent of successive LTC sets that are attached to it. This enables a continuous visualization of load flow from the input to the output. Furthermore, we mathematically relate the load flow with the deformation behavior of the mechanism. We can thus explain the deformation behavior of a number of compliant mechanisms from literature by identifying its LTC sets to visualize load flow. This method can also be used to visualize load flow in optimal stiff structure topologies. The insight obtained from this visualization tool facilitates a systematic building block based design methodology for compliant mechanisms and structural topologies.
The Role of Designer-Customer Collaboration for Product Customization and Assessment
Authors: Bordegoni Monica , Cugini Umberto
Published: March 2011

This paper addresses issues related to the assessment of product designs that today successfully uses virtual prototyping methods and techniques. Design assessment is usually performed by engineers and designers. Current trend is involving customers in the products design assessment in order to check the level of acceptability and satisfaction before proceeding with the production. In this view, methods for design review may be used in participatory design sessions where customers can intervene for customizing products. The paper presents a tool that has been originally developed for designers for the validation and modification of aesthetic properties of digital shapes, and that has also been used by customers, in participatory design sessions, for customizing their products.
Making the Most Out of Surrogate Models: Tricks of the Trade
Authors: Viana Felipe A. C. , Gogu Christian , Haftka Raphael T.
Published: March 2011

Design analysis and optimization based on high-fidelity computer experiments is commonly expensive. Surrogate modeling is often the tool of choice for reducing the computational burden. However, even after years of intensive research, surrogate modeling still involves a struggle to achieve maximum accuracy within limited resources. This work summarizes advanced and yet simple statistical tools that help. We focus on four techniques with increasing popularity in the design automation community: (i) screening and variable reduction in both the input and the output spaces, (ii) simultaneous use of multiple surrogates, (iii) sequential sampling and optimization, and (iv) conservative estimators.
Organic Rankine Cycle for Waste Heat Recovery in a Hybrid Vehicle
Authors: Hussain Quazi E. , Brigham David R.
Published: March 2011

The Rankine cycle is used commercially to generate power in stationary power plants using water as the working fluid. For waste heat recovery applications, where the temperature is lower, water is typically replaced by a carefully selected organic fluid. This work is based on using the waste heat in an automobile to generate electricity using the Organic Rankine cycle (ORC) with R245fa (1, 1, 1, 3, 3 penta-fluoropropane) as the working fluid. The electricity thus generated can be used to drive the accessory load or charge the battery which in any case helps improve the fuel economy. A simple transient numerical model has been developed that is capable of capturing the main effects of this cycle. Results show that exhaust heat alone can generate enough electricity that is capable of bringing about an improvement to the fuel economy under transient drive cycle conditions. Power output during EPA Highway drive cycle is much higher than EPA City due to higher exhaust mass flow rate and temperature. Time needed to reach operating conditions or in other words, the warm-up time plays an important role in the overall drive cycle output. Performance is found to improve significantly when coolant waste heat is used in conjunction with the residual exhaust heat to pre-heat the liquid. A sizing study is also performed to keep the cost, weight, and packaging requirement down without sacrificing too much power. With careful selection of heat exchanger design parameters, it has been demonstrated that the backpressure on the engine can be actually lowered by cooling off the exhaust gas. This lower backpressure will further boost the fuel economy gained by the electricity produced by the Rankine bottoming cycle.
Load-Transmitter Constraint Sets: Part II—A Building Block Based Methodology for the Synthesis of Compliant Mechanisms
Authors: Krishnan Girish , Kim Charles , Kota Sridhar
Published: March 2011

Designers have always conceptualized of load flow as a part of their initial design process for mechanisms and structures. However, the lack of mathematical representation of load flow makes it inappropriate to be included in systematic design processes. Load Transmitter Constraint (LTC) sets provide a mathematical framework for visualizing load paths in compliant mechanisms. In this paper we propose a systematic design methodology for compliant mechanisms by systematic combination of LTC sets. This enables the designer to conceptualize load flow and choose relevant LTC sets to enforce it. Apart from being intuitive this process gives an understanding of the importance of each member in the mechanism. Furthermore this theory enables accurate and deterministic design for given motion specification without the aid of extensive computation. In this paper we propose guidelines for the design of mechanisms with a single load flow path and multi load flow path, particularly relevant in shape morphing applications.
A Method for Service Function Improvement Starting From the Service Delivery Process
Authors: Nakajima Masataka , Kato Hiroshi , Shimomura Yoshiki
Published: March 2011

In the manufacturing sector, product-service systems (PSSs) have attracted considerable attention as a means to unify and integrate the design of products and services. In order to maximize customer value, the design of products and services should be integrated. Thus far, unified schemes related to service activities and product behaviors have been proposed in the field of service engineering. In these approaches, services are modeled from the viewpoint of function, and a service delivery process that is based on service activities and product behaviors is developed. However, when service providers attempt to improve their service, the existing PSS methods are inadequate from the viewpoint of providing suggestions for improvement. Therefore, this research aims to establish a method for PSSs to suggest improvements in their own service. Thus, in this paper, the authors propose a method for service function improvement that involves analysis of the service delivery process and enhances customer value.