bluuebunny/crossref_metadata_2025 huggingface dataset:
Selecting an Appropriate Metamodel: The Case for NURBs Metamodels
Authors: Turner Cameron J. , Crawford Richard H.
Published: June 2008

Metamodels are becoming increasingly popular for representing unknown black box functions. Several metamodel classes exist, including response surfaces and spline-based models, kriging and radial basis function models, and neural networks. For an inexperienced user, selecting an appropriate metamodel is difficult due to a limited understanding of the advantages and disadvantages of each metamodel type. This paper reviews several major metamodeling techniques with respect to their advantages and disadvantages and compares several significant metamodel types for use as a black box metamodeling tool. The results make a strong case for using Non-Uniform Rational B-spline (NURBs) HyPerModels as a generic metamodeling tool.
Utilization of Concept Selection Methods: A Survey of Finnish Industry
Authors: Salonen Mikko , Perttula Matti
Published: June 2008

Concept selection is an area of design research that has been under considerable interest over the years. There is, however, only little information on how the methods that have been presented in design research for this task have been adopted by industry. Thus, a survey was carried out in the Finnish industry. The results revealed that the degree of industrial utilization of formal concept selection methods was relatively low. Less than one out of four companies responded to use one or several of the formal methods included in the study: Pugh’s evaluation matrix, Rating matrices, or Analytic Hierarchy Process (AHP). Concept review meeting were reported as the most common approach for concept selection. However, a majority of the companies that did not utilize any formal method reported lacking effective and suitable methods for concept selection. The companies using formal methods were more satisfied. The first conclusion from the study is that there is a basis for a higher degree of utilization of formal concept selection methods in industry. Our second conclusion is that the existing formal concept selection methods do not entirely fulfill the needs of concept selection in an industry context. We propose that numerical concept selection methods should be further developed and extended to better support the decision-making practices of concept selection in industry. This type of concept selection is characterized by the participation of multiple decision makers through concept design reviews.
Free Oscillations of a Beam With a Local Non Linearity: Comparison of Mechanical Modeling and Experiments by Means of Wavelet Analysis
Authors: Argoul Pierre , Erlicher Silvano , Nguyen Tien-Minh
Published: June 2008

This paper deals with the analysis and modeling of a linear clamped beam with a local non-linearity. The non linear effects are due to large displacements of the thin beam clamped at one end and screwed to the main beam at the other end. This set-up was built and instrumented at the University of Lie`ge. First, assuming that the thin beam can be replaced by nonlinear springs, a dynamic sub-structuring method is used to obtain the governing non linear differential equations of the system. Free decay responses are then numerically computed and compared to those obtained experimentally. To make the comparison, the wavelet tool is then used and the wavelet processing of free decay mechanical signals is presented in detail. Instantaneous amplitudes and frequencies are extracted from the wavelet analysis of free decay responses of the system, for the first three fundamental response components and their associated super-harmonics. Numerical and experimental results are presented and compared.
Robust Design of Cellular Materials With Topological and Dimensional Imperfections
Authors: Seepersad Carolyn Conner , Allen Janet K. , McDowell David L. , Mistree Farrokh
Published: June 2008

A paradigm shift is underway in which the classical materials selection approach in engineering design is being replaced by the design of material structure and processing paths on a hierarchy of length scales for multifunctional performance requirements. In this paper, the focus is on designing mesoscopic material topology—the spatial arrangement of solid phases and voids on length scales larger than microstructures but smaller than the characteristic dimensions of an overall product. A robust topology design method is presented for designing materials on mesoscopic scales by topologically and parametrically tailoring them to achieve properties that are superior to those of standard or heuristic designs, customized for large-scale applications, and less sensitive to imperfections in the material. Imperfections are observed regularly in cellular material mesostructure and other classes of materials because of the stochastic nature of process-structure-property relationships. The robust topology design method allows us to consider imperfections explicitly in a materials design process. As part of the method, guidelines are established for modeling dimensional and topological imperfections, such as tolerances and cracked cell walls, as deviations from intended material structure. Also, as part of the method, robust topology design problems are formulated as compromise Decision Support Problems, and local Taylor-series approximations and strategic experimentation techniques are established for evaluating the impact of dimensional and topological imperfections, respectively, on material properties. Key aspects of the approach are demonstrated by designing ordered, prismatic cellular materials with customized elastic properties that are robust to dimensional tolerances and topological imperfections.
Effects of Uncertainty Reduction on Weight of Composite Laminates at Cryogenic Temperatures
Authors: Acar Erdem , Haftka Raphael T. , Johnson Theodore F.
Published: June 2008

The effect of uncertainty reduction measures on the weight of laminates for cryogenic temperatures is investigated. The uncertainties in the problem are classified as error and variability. Probabilistic design is carried out to analyze the effect of reducing the uncertainty on the weight. For demonstration, variability reduction takes the form of quality control, while error is reduced by including the effect of chemical shrinkage in the analysis. It is found that the use of only error control leads to 12% weight reduction, the use of only quality control leads to 20% weight savings and the use of error and variability control measures together reduces the weight by 37%. In addition, the paper also investigates how to improve the accuracy and efficiency of probability of failure calculations (performed using Monte Carlo simulation technique). Approximating the cumulative distribution functions for strains is shown to lead to more accurate probability of failure estimations than the use of response surface approximations for strains.
Stability Analysis of a Variable Spindle Speed Milling Process
Authors: Long X.-H. , Balachandran B.
Published: June 2008

In this effort, a stability treatment is presented for a milling process with a variable spindle speed (VSS). This variation is caused by superimposing a sinusoidal modulation on a nominal spindle speed. The dynamics of the VSS milling process is described by a set of delay differential equations (DDEs) with time varying periodic coefficients and a time delay. A semi-discretization scheme is used to discretize the system over one period, and the infinite dimensional transition matrix is converted to a finite dimensional matrix over this period. The eigenvalues of this finite dimensional matrix are used to determine the stability of the VSS milling operation with respect to selected control parameters, such as the axis depth of cut and the nominal spindle speed. The benefits of VSS milling operations are discussed by comparing the stability charts obtained for VSS milling operations with those obtained for constant spindle speed (CSS) milling operations.
Towards Model Simplification of Uncertain Complex Dynamical Systems
Authors: Runolfsson Thordur
Published: June 2008

The use of simulation models in the design and verification of complex industrial systems is becoming standard practice. All models of physical processes are uncertain either due to unknown/ignored phenomena or inherent uncertainty due to variations in operating conditions and/or physical properties. This paper considers the second class of problems where the uncertainty can be characterized through an external uncertain parameter that may be time dependent as well as random. We formulate an approach for analysis of such system based on the theory of Random Dynamical Systems and present a model reduction approach under the assumption of time scale separation between the system and parameter dynamics.
Magnetorheological Fluid Brake for a Force Feedback Glove for Virtual Environments
Authors: Blake Jonathan , Gurocak Hakan
Published: June 2008

The research and development of a Magnetorheological (MR) fluid brake for use in a force feedback glove is presented. The glove is a haptic interface for a virtual reality (VR) environment. The glove implements the MR fluid brakes to restrict motion of the VR user’s fingers. It is controlled by an input current and produces a corresponding output torque. The torque of the MR fluid brake is equivalent to the continuous torque exerted by a typical human index finger. Two sizes of brakes were developed to control the joints of the thumb, index, and middle fingers. The paper presents background and design details of implementing the MR fluid. The prototype designs of the MR fluid brakes are then introduced. Test procedures and results of the braking torque and response time are presented. Lastly, the implementation of the brakes into a force feedback glove is briefly discussed. Test results show that the MR fluid brake is capable of restricting the motion of a human finger.
Experimental and Theoretical Investigation of Conical and Cylindrical Isolators
Authors: Tongele T. N. , Chen T.
Published: June 2008

In practical situations where two interconnected systems are isolated from one another to prevent vibration transmission, isolators are inserted between the two systems. The ability of conical and cylindrical isolators to control longitudinal vibration transmission is investigated in this paper. Theoretical predictions obtained by means of finite element modeling are compared with experimental results. Both experimental and theoretical results have converged in pointing to the effectiveness and better performance of conical isolators compared to cylindrical isolators. While isolators investigated in this paper are made from plastic material called delrin, future investigations will compare conical and cylindrical isolators made from other types of material including composite material.
A Comprehensive Model for Cutting Dynamics
Authors: Dassanayake Achala V. , Suh C. Steve
Published: June 2008

A three dimensional dynamic model describing turning operation involving whirling caused by mass imbalance is presented. Both the workpiece and tool deflections affected by nonlinear regenerative forces with instantaneous cutting speed and feed are included. The work piece is modeled as a system of three rotors; namely, unmachined, being machined and machined, connected by a flexible shaft. Special focus is given to the middle rotor where cutting forces act and the new surface is being generated. The nonlinear behavior of the system is studied using instantaneous frequency. The stable and unstable situations are illustrated in time domain as well as time-frequency domain. Models with and without whirling are considered and two sets of results are compared with the experimental results published in the literature.
Nearfield Acoustic Holography Using Energy-Based Measurements
Authors: Harris Michael C. , Blotter Jonathan D. , Sommerfeldt Scott D. , de Bree Hans-Elias
Published: June 2008

Since its conception in 1980, nearfield acoustic holography (NAH) has become an accepted analysis tool with a number of commercial packages now available. One limitation of NAH is that the acoustic field is reconstructed through a spatial sampling. Therefore, this technique becomes less efficient at higher frequencies where microphone array spacing must be reduced. Analytical models have indicated that an NAH method relying on energy-based measurements will provide the same reconstruction resolution of current NAH methods with significantly fewer measurement locations. This would lead to a considerable savings in data acquisition time for scanning array systems and reduce the inefficiency at high frequencies. The energy-based reconstruction method will be introduced. Experimental results will be presented for a planar test case and the resulting reconstruction accuracy will be compared to the analytical prediction model.
Rule-Based Process Selection of Hole Making Operations for Integrated Process Planning
Authors: Sormaz Dusan N. , Khurana Pravin , Wadatkar Ajit
Published: June 2008

Process selection as a part of CAPP has captured significant attention in CAPP research. Procedures have been developed for backward and forward algorithms in process selection. Most of these procedures lack the complete integration of process selection into CAPP system. In this paper, we present the results of the development and prototype implementation for process selection module for hole making operations for integration with Math Based Manufacturing System already in use in industrial partner. We have developed architecture and implemented module for rule-based machining process selection of hole making operations. The architecture enables the interface from the Process Selection prototype to Math Based Manufacturing System (APPS). The prototype also includes the user interface for interaction with the process selection procedure. Actions for starting prototype from APPS, performing process selection steps and sending the result back to APPS have been developed and implemented.
Wrinkling and Free Vibration of Catenary-Supported Thin Membranes
Authors: Ding Hongli , Yang Bingen , Fang Houfei , Lou Michael
Published: June 2008

This paper is concerned with the wrinkling and free vibration analysis of catenary supported membranes. In the development, the use is made of a two-variable-parameter (2VP) model for the thin-film membrane, and tensioned bar model for the catenary support. The entire membrane structure is assembled through reinforcement of a shear-free constraint between the membrane and the supporting catenary, which leads to a global dynamic equation governing the free vibration of the catenary-supported membrane. The natural frequencies and modes shapes of the membrane are then computed. The proposed modeling and solution technique is illustrated in a numerical example.
A Hybrid Rod-Catenary Model to Simulate Nonlinear Dynamics of Cables With Low and High Tension Zones
Authors: Goyal S. , Perkins N. C.
Published: June 2008

Cables under very low tension may become highly contorted and form loops, tangles, knots and kinks. These nonlinear deformations, which are dominated by flexure and torsion, pose serious concerns for cable deployment. Simulation of the three-dimensional nonlinear dynamics of loop and tangle formation requires a 12th order rod model and the computational effort increases rapidly with increasing cable length and integration time. However, marine cable applications which result in local zones of low-tension very frequently involve large zones of high-tension where the effects of flexure and torsion are insignificant. Simulation of the three-dimensional dynamics of high-tension cables requires only a 6th order catenary model which significantly reduces computational effort relative to a rod model. We propose herein a hybrid computational cable model that employs computationally efficient catenary elements in high-tension zones and rod elements in localized low-tension zones to capture flexure and torsion precisely where needed.
On the Use of the HHT Method in the Context of Index 3 Differential Algebraic Equations of Multibody Dynamics
Authors: Negrut Dan , Rampalli Rajiv , Ottarsson Gisli , Sajdak Anthony
Published: June 2008

The paper presents theoretical and implementation aspects related to a new numerical integrator available in the 2005 version of the MSC.ADAMS/Solver C++. The starting point for the new integrator is the Hilber-Hughes-Taylor method (HHT, also known as α-method) that has been widely used in the finite element community for more than two decades. The method implemented is tailored to answer the challenges posed by the numerical solution of index 3 Differential Algebraic Equations that govern the time evolution of a multi-body system. The proposed integrator was tested with more than 1,600 models prior to its release in the 2005 version of the simulation package MSC.ADAMS. In this paper an all-terrain-vehicle model with flexible chassis is used to prove the good efficiency and accuracy of the method.
Modeling of an Anti-Tilting Outdoor Mobile Robot
Authors: Nasrallah Danielle Sami , Angeles Jorge , Michalska Hannah
Published: June 2008

This paper reports on the modeling of an anti-tilting outdoor mobile robot moving on an uneven terrain that is modeled as a warped, smooth surface. The dynamics has been derived using the natural orthogonal complement, and takes into account the terrain geometry, which has not been investigated before. The Euler-Rodrigues parameters have been chosen to describe the orientation of bodies in space because of their robustness. Simulation of the robot moving on distinct types of terrain are provided.
Towards Risk Based Design (RBD) of Space Exploration Missions: A Review of RBD Practice and Research Trends at NASA
Authors: Tumer Irem , Barrientos Francesca , Farhang Mehr Ali
Published: June 2008

This paper describes the concept of Risk Based Design in the context of NASA’s low volume, high cost missions. The issue of accounting for risk in the design lifecycle has been heavily discussed in the literature under several research topics, including: reliability, risk and uncertainty analysis, optimization, decision-based design and robust design. Due to the risky nature of space missions, NASA centers have adopted a variety of techniques—developing tools, procedures, and guidelines to mitigate risk. Most of these techniques, however, require significant amounts of detailed and possibly quantitative information, making them inapplicable to early stages of design, where the requirements and models are vague, decisions are tentative and probabilities are unknown. This survey paper first presents a brief description of a design environment at NASA as well as current risk-based design practices and methods. Then, a summary of the topics from the NASA’s Risk Management Conference is presented, followed by current research efforts within NASA to account for risk in early stage design. The purpose of this paper is provide a survey of NASA’s capabilities (or lack thereof) in accounting for risk in the early design phase. This work lays the foundation for more effective collaborations between NASA researchers and the academic research community.
Effect of Cant Deficiency on Rail Vehicle Performance
Authors: Marquis Brian , Greif Robert , Curtis Erik
Published: June 2008

Simplified train models are analyzed to assess the relationship of unbalance on carbody acceleration and wheel unloading during steady state curving motion. In this paper a half-car model appropriate for both power cars and tilting coach cars is theoretically analyzed. Models of this type are useful for examining static lean requirements as well as margins of safety at higher cant deficiencies in the Track Safety Standards of the Federal Railroad Administration (FRA). The suspension systems modeled and analyzed include the following types: rigid, flexible, tilting actuation, and combined flexible and tilting actuation suspension. Simplified formulas are derived which can be used as an analysis tool by railroad designers to assess vehicle performance. Parametric results are presented for vertical wheel unloading and lateral carbody acceleration as a function of cant deficiency. Results show that incorporation of tilting systems, better suspension designs and better track quality, are necessary in order to provide an equivalent level of margin of safety for operations at higher cant deficiency. The relationship of these results to limits in the Track Safety Standards is discussed.
Dynamic Analysis and Simulation of Vehicles Carrying Liquids During Braking
Authors: Biglarbegian Mohammad , Zu Jean W.
Published: June 2008

This paper presents two dynamic models of vehicles carrying liquids, namely single tractor and tractor-semitrailer. Both models incorporate suspension system and tire dynamics. Vehicles carrying fluids feature two subsystems: vehicle body and fluid subsystems. These two subsystems are coupled and to simplify the complicated solution, the coupled equations are solved separately using two different codes. Different braking moments are applied to the models and their dynamic behaviors are determined. It is shown that tractor-semitrailers need more braking moment than single tractor ones. As well, it turns out vehicles carrying fluids need a greater amount of moment in comparison to vehicles carrying solids to come to a complete standstill. Lastly, as the level of fluid inside the tanker increases (33% to 66%), the sloshing forces to the tanker’s walls increase. Therefore, it is revealed that tankers should be specially designed to address the characteristics and volume of fluid inside the tanker.
Synthesis of Structural Symmetry Driven by Cost Savings
Authors: Honda Tomonori , Nicaise Fabien , Antonsson Erik K.
Published: June 2008

An engineer presented with a design challenge often creates a symmetric solution. For instance, consider a table (front-back and left-right symmetry), a car (left and right symmetry), a bridge (front-back and left-right symmetry), or the space shuttle (left-right) symmetry. These examples may not be 100% symmetric, but their overriding features are remarkably similar. The reasons for the design of symmetric structures is not always clear. In some cases, like the table, symmetry may be a tradition. Similarly, the symmetry may be for aesthetic reasons. However in automated design algorithms, especially stochastic techniques, the output is often largely asymmetric, One reason for this is that fitness functions are not rewarded for symmetry. A possible resolution to this is to add a reward function for symmetry. Unfortunately, this approach is computationally intractable as well as arbitrary. In this paper a Genetic Algorithm based method is presented that rewards re-use of parts. The method is applied to a simple, idealized situation as well as to real design case. The results show that in some situations, symmetry naturally emerges from the synthesis, but that it does not provide clear performance advantages over asymmetric configurations.
Comparative Study of CAD Interrogation Capabilities: Commercial CAD vs. Design Exemplar
Authors: Summers Joshua D.
Published: June 2008

The design exemplar has been proposed as an approach to developing a CAD query language based upon an analysis of the design exemplar components, vocabulary, and extensions to support logical connectives. Design engineers create models of design artifacts with commercial Computer Aided Design (CAD) solid modeling systems. These systems stop short of providing support for querying and retrieving data from within the CAD data files. The design exemplar data structure and algorithm are offered in this paper as a new tool for interrogation of CAD models. The querying capabilities of a comprehensive commercial CAD system is compared with the querying capabilities of the design exemplar based upon user interaction cues. The results of this comparison indicate that for batch processing of CAD model interrogation, the design exemplar provides, based upon user interaction, a superior and more efficient approach.
Vibratory Data Fusion for Gearbox Fault Detection Using Autoassociative Neural Networks
Authors: Ferna´ndez del Rinco´n Alfonso , Garci´a Ferna´ndez Pablo , Viadero Rueda Fernando , Sancibria´n Herrera Ramo´n
Published: June 2008

This paper deals with gearbox fault detection by vibration analysis. A new processing procedure is proposed which uses the information from several acquisition channels. The approach is based on the assumption that there is a non-linear relationship among the instantaneous vibration magnitude registered for each measurement location. This relationship is captured in the connection weight matrix of an Autoassociative Artificial Neural Network (AANN), which is trained to provide an output vector equal to the input one. In this work, the time synchronous average signal (TSA) for each channel corresponding to the no fault condition is used to train an AANN. Once the AANN is trained, it is used with new data registers as a linear prediction error filter. If the new register contains the same data structure as the training set the prediction error will be low and the machine is working properly. Otherwise, when the new register differs from the training set, as a consequence of a fault, prediction error will be increased in each channel. In this way the information from not only one channel but more than one is used for fault detection and diagnosis as the error signal depends on the TSA signal from all channels. The proposed approach provides a new tool for gear fault detection that is compared on the basis of experimental registers with the most traditional gear processing tools based on TSA such as residual and regular signals. The possibility of generalizing the net prediction capabilities using a training data set that contains several load cases is also explored.
A Compliant Contact Model Including Interference Geometry for Space Robotic Systems
Authors: Luo Lianzhen , Nahon Meyer
Published: June 2008

Modeling of contact with the environment is an essential capability for the simulation of space robotics system, which includes tasks such as berthing and docking. The effect of interbody contact on the robotics system has to be determined to predict potential problems in the design cycle. A compliant contact dynamics model is proposed here, which considers most possible contact situations for a wide diversity of possible object shapes and using interference geometry information. A uniform formula is provided to determine the contact force as a function of geometric parameters and material properties. A corresponding geometric algorithm is provided in order to obtain the necessary geometric parameters. Some simulation results are presented based on the implementation of the geometric algorithm.
Facilitating Collaborative Design: A Review on Design Representations and Workstations
Authors: Okudan Gu¨l E. , Medeiros Deborah J.
Published: June 2008

This paper reviews recent developments and persisting challenges in facilitating collaborative engineering design. The review has two foci: 1) design information and representations, and 2) engineering workstations. Recent developments regarding these foci are discussed for their contribution to facilitating collaborative design. The paper concludes with directing attention to current challenges and recommendations for research.
Local Flow Variation Method for Damage Identification
Authors: Liu Ming , Chelidze David
Published: June 2008

In this paper, a damage identification method called local flow variation is introduced. It is a practical implementation of a phase space warping concept. A hierarchical dynamical system is considered where a slow-time damage process causes drifts in the parameters of fast-time system describing measurable response of a structure. The method is based on the hypothesis that the probability distribution function of the fast-time trajectory in its phase space is a function of damage state. In this method, an ensemble of estimated expectations of trajectory in different locations of the reconstructed phase space is used as a damage feature vector. Using these feature vectors, damage identification is realized by a smooth orthogonal decomposition. An experiment is conducted to validate the method. A two dimensional slow-time damage process is identified from experimental fast-time data. Although damage identification through the local flow variation is not as accurate as trough phase space warping, the required computing time is about two-orders-of-magnitude shorter.
An Optimization Based Methodology to Design Flexible Systems Subjected to Changing Operating Conditions
Authors: Khire Ritesh A. , Mullur Anoop A. , Messac Achille
Published: June 2008

Flexible systems maintain a high performance level under changing operating conditions or design requirements. Flexible systems acquire this powerful feature by allowing critical aspects of their design con guration to change during the operating life of the product or system. In the design of such systems, designers are often required to make critical decisions regarding the exible and the non-exible aspects of the design con guration. We propose an optimization based methodology to design exible systems that allows a designer to effectively make such critical decisions. The proposed methodology judiciously generates candidate optimal design versions of the exible system. These design versions are evaluated using multiobjective techniques in terms of the level of exibility and the associated penalty. A highly exible system maintains optimal performance under changing operating conditions, but could result in increased cost and complexity of operation. The proposed methodology provides a systematic approach for incorporating designer preferences and selecting the most desirable design version — a feature absent in several recently proposed exible system design frameworks. The developments of this paper are demonstrated with the help of a exible three-bar-truss design example.
Microstructure Design for a Rotating Disk: With Application to Turbine Engines
Authors: Sintay Stephen D. , Adams Brent L.
Published: June 2008

Through the use of generalized spherical harmonic basis functions a spectral representation is used to model the microstructure of cubic materials. This model is then linked to the macroscopic elastic properties of materials with Cubic Triclinic and Cubic Axial-symmetric symmetry. The influence that elastic anisotropy has on the fatigue response of the material is then quantified. This is accomplished through using the effective elastic stiffness tensor in the computation of the crack extension force, G. The resulting material model and macroscopic property calculations are the foundation for a software package which provides an interface to the microstructure. The Microstructure Sensitive Design interface (MDSi) enables interaction with the material design process and provides tools needed to incorporate material parameters with traditional design, optimization, and analysis software. The microstructure of the material can then be optimized concurrently other engineering models to increase the overall design space. The influence of microstructure on the performance of a spinning disc is explored. The additional design space afforded by inclusion of the material parameters show that for both Cubic Triclinic and Cubic Axial-symmetric material symmetry conditions G can be reduced by more than an order of magnitude. For the Cubic Axial-symmetric condition a Cube <001> fiber texture and a <111> fiber texture are identified as the best performing orientation distributions.
Transition of Neural Signals on Cylindrical Shells With Various Curvatures
Authors: DeHaven J. G. , Han Y. , Tzou H. S.
Published: June 2008

Sensing and control are essential to achieving the high performance and high precision of modern aerospace structures and systems. Typical off-the-shelf sensors placed at discrete locations usually add additional weights and thus often influence dynamic responses of precision systems. Unlike the conventional discrete add-on sensors, thin lightweight piezoelectric layers can be spatially spread and distributed over the surfaces of precision structures. The purpose of this study is to investigate microscopic neural signal generations from infinitesimal piezoelectric neurons over a cylindrical shell panel of various curvature angles and to determine dominating signal components resulting from longitudinal or circumferential membrane strains or longitudinal or circumferential bending strains. Dynamic equations of cylindrical shells are defined first, followed by free-vibration analysis. Then, mode shape functions and modal spatial strain distributions are used to determine the signal generation of distributed neuron sensors laminated on a linear cylindrical shell panel. The microscopic signal generations of infinitesimal piezoelectric sensors or neurons are investigated for three different curvature angles, i.e., β* = 30°, 90°, and 150°, of a simply-supported cylindrical shell panel. Evaluating these three cases suggests that as the curvature increases from 0° to 360°, the neural signals from the membrane strain dominate for lower natural modes before the neural signals from the bending strain become dominating as the mode increases.
Component Based Modeling of Electromechanical Systems
Authors: Vaze Shilpa A. , Krishnaswami Prakash , DeVault James
Published: June 2008

Simulation methods for electromechanical systems should accommodate their interdisciplinary nature and the fact that these systems often display qualitative changes in system behavior during operation, such as saturation effects and changes in kinematic structure. Current approaches are either based on deriving the system equations by applying a single formulation to all problem domains, or they are based on trying to integrate different software packages/modules to solve the interdisciplinary problem. In this paper, we present a component-based approach which allows the governing equations of each component to be defined in terms of its natural variables. The different component equations are then brought together to form a single system of differential-algebraic equations (DAE’s), which can be numerically solved to obtain the system response. The fact that we have an explicit, unified form of the system governing equations means that this formulation can be easily extended to design sensitivity analysis and optimization of electromechanical systems (EMS). The formulation includes monitor functions which can be used to detect when a qualitative system change has occurred, and to switch to a new set of governing equations to reflect this change. A single step integrator is used to make it easier to switch to a new system behavior, since this will always require a restart of the integrator. There is considerable flexibility in how the components can be defined, and connections between components are themselves modeled as special types of components. Examples of components from the mechanical and electrical side are presented, and two numerical examples are solved to illustrate the efficacy of the proposed method. One example is a link that is driven by a DC motor through a gearbox. The results of this example were verified against Simulink, and good agreement was observed. The second example is a motor driven slider-crank mechanism. The method can be extended to include components from any domain, such as hydraulics, thermal, controls, etc., as long as the governing equations can be written as DAE’s.
A New Methodology for Robot Controller Design
Authors: Peters Jan , Mistry Michael , Udwadia Firdaus , Schaal Stefan
Published: June 2008

Gauss’ principle of least constraint and its generalizations have provided a useful insights for the development of tracking controllers for mechanical systems [1]. Using this concept, we present a novel methodology for the design of a specific class of robot controllers. With our new framework, we demonstrate that well-known and also several novel nonlinear robot control laws can be derived from this generic framework, and show experimental verifications on a Sarcos Master Arm robot for some of these controllers. We believe that the suggested approach unifies and simplifies the design of optimal nonlinear control laws for robots obeying rigid body dynamics equations, both with or without external constraints, holonomic or nonholonomic constraints, with over-actuation or underactuation, as well as open-chain and closed-chain kinematics.
A Context-Based Approach to Engineering Design Negotiation
Authors: Geslin Mathieu , Jin Yan
Published: June 2008

Complex and large-scale engineering design problems require a collaborative approach in order to be completed in a timely manner. Designers involved in such work are making collaborative design decision, and often have to negotiate to address intricate problems and resolve their discrepancies while exploring the design space, generating new ideas and compromising for agreement. Advances in negotiation research have been made in social psychology, distributed artificial intelligence, and decision theory, but few have been applied to design. We advocate that design context information is of paramount importance in the decision-making process. In this paper, an argumentation-based negotiation model is introduced to support collaborative design decision-making. This model relies on clear design context model, argument model, negotiation protocol and strategies. In this paper, we successively detail each of these components and conclude with a discussion on a real-world case example and our future research direction.
Multi Mode Vibration Control and Broder Band Motion Control of Three Dimensional Shaking Table
Authors: Wakasugi Tsunehiro , Watanabe Toru , Seto Kazuto
Published: June 2008

This paper deals with a new system design method for motion and vibration control of a three-dimensional flexible shaking table. An integrated modeling and controller design procedure for flexible shaking table system is presented. An experimental three-dimensional shaking table is built. “Reduced-Order Physical Model” procedure is adopted. A state equation system model is composed and a feedback controller is designed by applying LQI control law to achieve simultaneous motion and vibration control. Adding a feedforward, two-degree-of-freedom control system is designed. Computer simulations and control experiments are carried out and the effectiveness of the presented procedure is investigated. The robustness of the system is also investigated.
Natural Frequency Analysis of a Fixed-Fixed Cracked Plate in Bending
Authors: Nguyen Hien Luong Thi , Vuong Quang Giang
Published: June 2008

The paper aims to study the dynamic behavior of a bending thin plate with fixed-fixed ends after crack occurrence. Using the FEM with an 8-node quadrilateral isoparametric element based on the Ressner-Mindlin’ theory of plate, the program CRACK-PLATE is developed to investigate the effect of crack length and position on the dynamic response of plate. The natural frequencies and modes are calculated and analyzed numerically for the non-faulty case and additionally with the edge and the central crack. In order to achieve a high accuracy, a singularity element of Barsoum is combined. The numerical results show that the natural frequencies are very sensitive to the crack presence in bending plate. It provides a basis to carry out the inverse problem for crack identification based on the dynamic characteristics of plates.
Technique to Handle Local Constraints in Multibody Dynamics
Authors: Kamiyama Naoto , Aki Masahiko , Sagane Takahito , Tajima Hiroshi , Seto Kazuto
Published: June 2008

Sometimes we have a system that can be expressed basically by independent variables, with some redundant variable groups to decide only small parts of the system respectively. If the constrains of these redundant variables in each group are not coupled with each other, namely these are no common variables, we call them as local constraints. Example of local constrains are Euler parameter constraint and constrains of link mechanism of car suspension system. The necessity of redundant variables can also be limited for position level. Within the simple nonholonomic system we can always select the appropriate independent velocities to express the other velocity level variables. If the system has only local constraints, it is inefficient to use the typical DAE formulation, which handled all the constraints simultaneously. The technique we explain in this paper has advantage in calculation time and also in the sense of constrain stabilization. This paper gives a basic idea of the technique and its general formulation. Also three examples are explained which we used to confirm the effectiveness of the technique. We got a good result of constrains stabilization. More detailed examination about the calculation time and the constraint stabilization is planned in near future before we proceed to construct a simulation program of complex elastic vehicle model.
History, Perspective and Outlook for Media Transport Simulation Using Multibody Dynamics
Authors: Ross Brant A.
Published: June 2008

Media transport models for multibody dynamics simulation are different than the models typically implemented in the automotive and aerospace industries. The physical interaction between heavy, stiff components and light sheets present special challenges for engineering design. Feedback from both physical testing and simulation is needed. The emergence of a new generation of specialized application modules that are based on commercial multibody dynamics software provides engineers with a more approachable tool for simulation. The application of process automation is described. The requirements and benefits of 2D and 3D media transport models are different and are best addressed with separate application modules. Considerations for modeling and simulating a photo-receptor belt are reviewed. The future of media transport simulation is explored.
Vibration Control Using Connected Control Device for Two Identical Structures Arranged in Parallel
Authors: Fujimura Kiyofumi , Makita Kazuya , Watanabe Toru , Seto Kazuto
Published: June 2008

This paper deals with vibration control using the optimal design strategy of the connected control device for flexible structures with same dynamic properties. One of the authors had already proved effectiveness of connected control method for vibration control of flexible structures arranged in parallel. However, its control performance is degraded as the natural frequencies of structures become closer. To overcome this problem, the authors present a modified control mechanism in which the actuators are connected to the structures with differences in its connecting position by using long arms named “supporting structures”. However, the optimal design strategy for vibration control device has not been established yet. In this report, the optimal design strategy of passive control is presented. Computer simulations and the experiments are carried out and the effectiveness of the presented vibration control designed by the connected control device is confirmed.
Reduced Order Modelling in Nonlinear Mechanical Oscillators With Energy Pumping
Authors: Ma Xianghong , Vakakis Alexander F. , Bergman Lawrence A.
Published: June 2008

Energy pumping in nonlinear mechanical oscillators has been discovered and studied in mechanical systems consisting of weakly coupled, linear and nonlinear components [1–3]. In this paper this phenomenon is further studied and numerically verified on an 11 degree of freedom system. It also presents a technique to create low dimensional models for energy pumping systems using the Karhunen-Loeve (K-L) decomposition method. It is shown that energy pumping can be identified from the dominant K-L modes. The low dimensional models are used to reconstruct the system responses. From the comparisons between the reconstructed and simulated response, we can see that the K-L mode-based low-dimensional model can represent the system responses; it can be used for monitoring, diagnosis and control purposes.
Plug-in Toolkit, Integration Platform, Engineering Application Framework Concept in CAE Software
Authors: Jang Kyungchun , Choi Juhwan , Choi Jinhwan , Koo Jachoon
Published: June 2008

In this paper, one method for the process of CAE software’s development is proposed. In order to develop CAE software efficiently and quickly 3 concepts are built, Engineering Application Framework, Plug-in Toolkit and Integration Platform. These concepts are based on object-oriented idea and include CAE’s characteristics. Engineering Application Framework is for the basic foundation of CAE software. Plug-in toolkit is for the fast and easy extension of CAE software. And integration platform will solve the problem of control and managing according to the various extensions. The theory and operating process of each concept is investigated.
Preparing Future Faculty for Teaching Engineering Design
Authors: Terpenny Janis P. , Goff Richard M.
Published: June 2008

This paper reports on a new core course that has been developed for the recently established Department of Engineering Education at Virginia Polytechnic Institute and State University (Virginia Tech). The course is focused on preparing future engineering faculty members to teach engineering design as well as how to function more effectively in industry design environments. Material related to theories of student learning and appropriate pedagogical approaches to teaching an open-ended subject such as engineering design are included. Having successfully completed this course, students are able to describe engineering design process and compare and contrast design across engineering and non-engineering disciplines. Students develop a syllabus for a design course in their own discipline, including assignments and projects. They also learn about effective project management and are able to characterize and demonstrate effective means of teaching/coaching/mentoring of various design projects. As future educators, students are able to describe the ABET (Accreditation Board for Engineering and Technology) requirements for design courses (Capstone, etc.), describe and demonstrate various theories of learning and pedagogy, and are able to navigate the course design and approval process. Descriptions of student mentoring of K-12 design teams in the FIRST LEGO® League competition are also provided.