bluuebunny/crossref_metadata_2025 huggingface dataset:
3D_Mec: An Application to Teach Mechanics
Authors: Ros J. , Gil J. , Zabalza I.
Published: June 2008

3D_Mec is a GPL-ed application for the solution of problems related to Mechanics. It is specially well suited for the direct kinematic and dynamic simulation of general systems. Is has been used during the last 10 years as a practical complement of the “Mechanics” Bachelor Course in Mechanical Engineering at the Public University of Nabarre-Spain. The main focus of the application is teaching Classical Mechanical principles and their applications. To that end 3D_Mec is constructed over an underlying Symbolic Algebra Kernel that allows the user to express itself in a language that closely resembles that of the mechanics and its level of abstraction. Classical kinematical primitives: Point, Basis and Reference, and set of operators acting upon them; support for vector and tensors, automatic basis change, ... relieve the user from the tedious algebraic manipulations directing his focus at the concept. A set of OpenGL based graphical primitives allow to represent the system and its simulation, and to create clips from them, it also represents a valuable way to check for the validity of the defined vectors and equations. 3D_Mec can also be used as a preprocessor or postprocessor, this is accomplished exporting the defined variables and different sets of equations in the popular language MatLab [3], where the integration or a different problem can be readily made based on well formed tested equations, results can be easily imported back from files containing a temporal series of the different variables. The program is also being used successfully in this way in “Dynamics of MultiBody Systems” PhD. course.
Dynamic Stability of a Single-Axis Vibratory MEMS Gyroscope
Authors: Wang Tianfu , Asokanthan Samuel F.
Published: June 2008

Instabilities in a vibrating MEMS gyroscope that is subject to periodic fluctuations in input angular rates are investigated. For the purpose of acquiring stability conditions, when the angular rate input is subject to small intensity periodic fluctuations, dynamic behavior of periodically perturbed linear gyroscopic systems is studied in detail. An asymptotic approach based on the method of averaging has been employed for this purpose, and closed-form conditions for the onset of instability due to parametric resonances have been obtained. A numerical approach based on the Floquet-Lyapunov theory is employed for validating the analytical stability predictions. Furthermore, for characterizing the effect due to change in angular rate input, an in-depth natural frequency analysis has been performed. Stability predictions have been illustrated via stability diagrams in the excitation amplitude-frequency space.
A New Deterministic Approach Using Sensitivity Region Measures for Multi-Objective Robust and Feasibilty Robust Design Optimization
Authors: Li Mian , Azarm Shapour , Boyars Art
Published: June 2008

We present a deterministic, non-gradient based approach that uses robustness measures for robust optimization in multi-objective problems where uncontrollable parameters variations cause variation in the objective and constraint values. The approach is applicable for cases with discontinuous objective and constraint functions, and can be used for objective or feasibility robust optimization, or both together. In our approach, the parameter tolerance region maps into sensitivity regions in the objective and constraint spaces. The robustness measures are indices calculated, using an optimizer, from the sizes of the acceptable objective and constraint variation regions and from worst-case estimates of the sensitivity regions’ sizes, resulting in an outer-inner structure. Two examples provide comparisons of the new approach with a similar published approach that is applicable only with continuous functions. Both approaches work well with continuous functions. For discontinuous functions the new approach gives solutions near the nominal Pareto front; the earlier approach does not.
Methodology for Market Analysis of CHP Systems
Authors: Oggianu Stella Maris , Florea Razvan , Mun˜oz J. Ricardo , Poncia Guido , Carriere Thierry , Luo Dong
Published: June 2008

The methodology presented in this paper is implemented through a tool that integrates the functionality needed to perform accurate CHP market analysis. This tool includes the selection of target market segments and representative buildings, hourly building loads and characteristics, alternative CHP configurations, control rules and equipment management strategies, as well as detailed utility rates, components-based economics and reliability data. Results obtained by using the full capability of this tool are compared with less rigorous screening methods that use average building loads, constant equipment characteristics, and average utility rates. The comparison of results demonstrates that the utilization of the latter methods allows faster market screenings, but generates results that may lead to loss of capital investment, equipment operation and designs that are far from optimal, and erroneous energy policies.
Design and Application of a Nonlinear Energy Sink to Mitigate Vibrations of an Air Spring Supported Slab
Authors: Goyal Sanjay , Whalen Timothy M.
Published: June 2008

In this paper we consider the application of a nonlinear energy sink (NES), a passive isolation device, to damp out energy from the low frequency modes of an air-spring supported slab to be installed at Purdue University’s Birck Nanotechnology Center. Analytical expressions to obtain energy sink design parameters, given some primary system specifications, have been derived. These expressions are then used to design the NES for the Birck air-spring supported slab. The designed NES is then analyzed via finite elements to study its efficacy in absorbing low frequency vibration from the slab. The study reveals that NES can serve as a good aid in dissipating vibrational energy induced by small disturbances in the slab.
The Dynamics of a Cyclic Ring of Coupled Duffing Oscillators
Authors: Folley Christopher , Bajaj Anil K.
Published: June 2008

The dynamics of a planar ring of N coupled identical, damped Duffing oscillators with external excitation is considered. Each oscillator is in 1:1 resonance with all other oscillators. The external forcing is a mono-frequency excitation near primary resonance with each oscillator and the analysis is considered in the context of weakly nonlinear systems. The symmetry of the system is exploited to determine, for an arbitrary number of oscillators, all possible classes of periodic solutions at the excitation frequency. These are fixed-point solutions for the system and are determined by the averaged equations. These solutions are classified into standing waves, traveling waves, and motions in-phase with the external forcing. Linear stability analysis is described for each solution class containing the highest degree of symmetry. To continue the study to motions with smaller degrees of symmetry, numerical simulations using the bifurcation analysis and branch continuation software AUTO 97 are utilized. The study presents the specific example of the dynamics of three Duffing oscillators.
Ontology Formalization of Product Semantics for Product Lifecycle Management
Authors: Patil Lalit , Dutta Debasish , Sriram Ram
Published: June 2008

Product Lifecycle Management (PLM) is a concept that takes into account that the development of a product is influenced by knowledge from various stakeholders throughout its lifecycle. Computing environments in the PLM framework are expected to have several independent information resources. This requires a meaningful formal representation of product data semantics throughout the product’s lifecycle. This paper presents an ontological approach to formalize product semantics into a Product Semantic Representation Language (PSRL). Building blocks to develop the explicit, extensible and comprehensive PSRL are described. The PSRL is open and based on standard W3L OWL constructs. The extensibility is demonstrated by considering an example product. The representation and the method of its development is expected to support several applications in the context of PLM. The use of OWL will enable the provision of the application software and information resources as Web services in the context of the Semantic Web.
Allocating Tolerances Statistically With Tolerance-Maps and Beta Distributions: The Target a Planar Face
Authors: Ameta Gaurav , Davidson Joseph K. , Shah Jami J.
Published: June 2008

A new math model for geometric tolerances is used to build the frequency distribution for clearance in an assembly of parts, each of which is manufactured to a given set of size and orientation tolerances. The central element of the new math model is the Tolerance-Map® (T-Map®); it is the range of points resulting from a one-to-one mapping from all the variational possibilities of a feature, within its tolerance-zone, to a specially designed Euclidean point-space. A functional T-Map represents both the acceptable range of 1-D clearance and the acceptable limits to the 3-D variational possibilities of the target face consistent with it. An accumulation T-Map represents all the accumulated 3-D variational possibilities of the target which arise from allowable manufacturing variations on the individual parts in the assembly. The geometric shapes of the accumulation and functional maps are used to compute a measure of all variational possibilities of manufacture of the parts which will give each value of clearance. The measures are then arranged as a probability density function over the acceptable range of clearance, and a beta distribution is fitted to it. The method is applied to two examples.
Control of 3D Snake-Like Locomotive Mechanism Based on Continuum Modeling
Authors: Date Hisashi , Takita Yoshihiro
Published: June 2008

An effective control method that achieves movement over a small ridge as an example of three-dimensional (3D) snake-like creeping locomotion is presented. The creeping robot is modeled as a continuum with zero thickness capable of generating bending moment at arbitrary points. Under a simplified contact condition, the optimal bending moment distribution in terms of a quadratic cost function of input can be obtained as a function of curvature by solving an isoperimetric problem. The solution is well suited to an articulated body consisting of finite number of links. The model is demonstrated through simulations and experiments using a prototype robot to be effective for traversing smooth 3D terrain.
Expressiveness of the Design Exemplar
Authors: Summers Joshua D.
Published: June 2008

As new representations are introduced to model various aspects of engineering design or to support computer aided design automation systems, these representations should be evaluated with respect to their intrinsic and extrinsic properties. One such property that is explored in this paper is “representational expressiveness”. This paper provides a systematic approach to exploring the expressiveness of new design representations by providing an evaluation of the design exemplar with respect to expressiveness. This expressiveness is decomposed into: coverage of vocabulary, flexibility of definition of vocabulary, type of vocabulary, mappability to existing representations, and support of basic design tasks. The design exemplar is examined with respect to these aspects of expressiveness, systematically laying a foundation for the intrinsic justification for basing future design automation systems on the principles of the design exemplar. This paper is not intended to be a comprehensive review of all aspects of the design exemplar. Rather, this paper is written to compel the design automation community to begin to develop a more systematic and reasoned approach in evaluating the automation systems and representations that are introduced in our research.
Roles and Observations of a Graduate Design Coach
Authors: Powers Lance M. , Summers Joshua D.
Published: June 2008

This paper discusses the roles that a graduate student coach experienced while working with an undergraduate design team in the development of a low, cost, low volume plastic injection modeling machine. Identified roles include: design tool teacher, design reviewer, project manager, and customer. A critique of the roles, including times spent in each role, is provided. This experience created generally higher satisfaction among the students and among the customers than had been previously seen in similar projects. Based upon this experience, it is justified to consider incorporating graduate design students as design coaches in senior design project teams.
Reliability-Based Topology Optimization Considering Multicriteria Using Frame Elements
Authors: Mogami Katsuya , Izui Kazuhiro , Nishiwaki Shinji , Yoshimura Masataka , Kogiso Nozomu
Published: June 2008

Since decision-making at the conceptual design stage critically affects final design solutions at the detailed design stage, conceptual design support techniques are practically mandatory if the most efficient realization of optimal designs is desired. Topology optimization methods using discrete elements such as frame elements enable a useful understanding of the underlying mechanics principles of products, however the possibility of changing prior assumptions concerning utilization environments exists since the detailed design process starts after the completion of conceptual design decision-making. In order to avoid product performance reductions due to such later-stage environmental changes, this paper discusses a reliability-based topology optimization method that can secure specified design goals even in the face of environmental factor uncertainty. This method can optimize mechanical structures with respect to two principal characteristics, namely structural stiffness and eigen-frequency. Several examples are provided to illustrate the utility of the method presented here for mechanical design engineers.
Spatial Motion of a String Subjected to Two Harmonic Excitations With Different Frequencies
Authors: Kamiya Keisuke , Yasuda Kimihiko
Published: June 2008

This paper studies spatial motion of a stretched string subjected to two harmonic excitations with different frequencies. Two cases are considered, one in which both excitations are in a plane, and one in which they are perpendicular to each other. First, theoretical analysis by the method of multiple time scales is conducted. It is found that in the former case sub-combination resonance and summed-and-differential combination resonance of whirling type can occur, and in the latter case sub-combination resonances parallel and perpendicular to the excitations and of whirling type can occur. Then, experiment is conducted. In the experiment, it was confirmed that the same types of motions as those predicted in the theoretical analysis occured. In addition, it was found that for the case in which the excitations are in a plane the response is sensitive to the difference between the natural frequencies in the two perpendicular directions. Finally, effect of the difference between the natural frequencies is studied.
Learning Transfer Among Solid Modelers: An Analysis of Icon Recognition
Authors: Rutkowski Raymond J. , Okudan Gu¨l E.
Published: June 2008

Selecting the “right” solid modeling software is a complex, multi-criteria decision-making problem. Some of these criteria relate to ease of learning, educational materials built into the software, learning curve issues, performance of the software for different solid modeling functions, operations and utilities, and cost. Beyond selecting the right software, the decision-maker should also be concerned about (1) conceptual learning of the solid modeling topics while “the right software” is being used, and (2) transfer of conceptual learning between solid modelers. This is because a sound conceptual learning using one software might increase the probability of learning another in less time. Accordingly, this paper investigates the impact of icon recognition as an aid to transfer conceptual learning between solid modelers. The investigation includes a review of the literature on icon design and usage as it relates to solid modeling, in addition to an experiment in which the icon recognition correctness for over 20 operation icons were compared across two modelers. The results shed light into the impact of icon designs on the transfer of learning between solid modelers using the correct recognition counts as the transfer measure.
Scalable HPC Simulations of Flexible Multibody Index-3 Dynamic Systems
Authors: Sandhu Sukhpreet S. , Kanapady Ramdev , Tamma Kumar K.
Published: June 2008

In this paper a highly scalable parallel formulation of the primal-dual technique is presented for index-3 constrained flexible multi-body dynamics system. The key features of the primal-dual approach are constraint preservation, preserving the original order of accuracy of time integration operators that are employed, and faster convergence rates of nonlinear iterations for the solution of flexible multi-body dynamical systems. In addition, this technique not only preserves the underlying properties of time integration operators for ordinary differential equations, but also eliminates the need for index reduction, constraint stabilization and regularization approaches. The key features of the parallel formulation of rigid and flexible modeling and simulation technology are capabilities such as adaptive high/low fidelity modeling that is useful from the initial design concept stage to the intermediate and to the final design stages in a single seamless simulation environment. The examples considered illustrate the capabilities and scalability of the proposed high performance computing (HPC) approach for large-scale simulations.
Building Sequence of Boundary Model in Layered Manufacturing
Authors: Eiamsa-ard Kunnayut , Ruan Jianzhong , Ren Lan , Liou F. W.
Published: June 2008

Even though building functional metal parts directly from CAD files has been the focus of many researches for many years, parts made by Layered Manufacturing (LM) have limited surface accuracy and long build time due to the sacrificial support structures. The Multi-Axis Laser Aided Manufacturing Process (LAMP) system improves build time by adding two more rotation axes to the system in order to reduce the support structures. The strategy to decompose the part model to sub-volumes or cells and the algorithm to arrange the deposition of those cells are discussed. The problems and questions of how much material should be deposited along the determined directions are also addressed in this paper.
Transition Curves for Nonhomogeneous Mathieu Equation
Authors: Younesian D. , Esmailzadeh E. , Sedaghati R.
Published: June 2008

The generalized form of the non-homogeneous Mathieu differential equation is analyzed in this paper. This type of differential equation arises from dynamic behavior of a pendulum subjected to the butterfly support motion. The Lindstedt-Poincare’s technique is considered in order to obtain the analytical solutions. The transition curves in some special cases are presented and their related periodic solutions with periods of 2π and 4π are obtained. Numerical simulation is carried out for some typical points in ε-δ plane.
Passage Through Resonance in a Three Degree-of-Freedom Vibration Isolation System
Authors: Kawana Ryo , Tokoyoda Tetsuro , Sato Kazushige , Yoshizawa Masatsugu , Sugiura Toshihiko
Published: June 2008

This paper deals with transient nonlinear vibration of a rigid body suspended on a foundation by elastic springs and constrained in a plane. In such a three degree-of-freedom vibration isolation system, we assume that ‘2-1-1’ internal resonance exists between the vertical and horizontal vibrations of the rigid body and the rotational vibration about its center of gravity. Next, the vibration of the rigid body is captured into or passes through resonance when the rotation speed of an unbalanced rotor equipped with the rigid body is increased. We theoretically examined the transient behavior of passage through resonance under the condition that a DC motor directly drives the unbalanced rotor with a limited electric current. Moreover, the experiment was conducted with a physical model of such a system, and transient oscillations through resonance were observed and compared with theoretical results in a few cases of limited currents.
Towards Collaborative Innovation Via Product Lifecycle Management (PLM): Status Review and Technology Trend
Authors: Ming X. G. , Lu W. F. , Yan J. Q. , Ma D. Z.
Published: June 2008

Today’s global economy makes enterprise face ever-increasing challenges for short time-to-market, reduced time-to-volume, decreased time-to-profit. This requires companies closely work with each other for continuous innovation by leveraging intellectual property. Product Lifecycle Management (PLM) is recognized as one of leading technologies to facilitate enterprises to tackle these challenges. Following this trend, based on the complete analysis of business drivers, industry requirements, limit of current solution, and recent state-of-the-art review in the domain related to PLM, this study proposes the comprehensive future technology solutions for PLM. Potential industrial impact of the developed PLM technology is analyzed. It is hoped that the proposed PLM technology trend will form the frontier basis for further academic research and industrial application of PLM technology.
Long Term Ride Dynamics of Large Order Vehicle Models With Nonlinear Suspension
Authors: Metallidis P. , Stavrakis I. , Verros G. , Natsiavas S.
Published: June 2008

This work presents a systematic methodology for investigating long term ride dynamics of large order vehicle models in a computationally efficient way. First, the equations of motion for each of the main structural components of the vehicle are set up by applying finite element techniques. The resulting composite models possess strongly nonlinear characteristics and as their order increases the existing numerical methodologies for a systematic determination of their dynamics become inefficient to apply. Therefore, the first step of the present methodology is to reduce the dimensions of the original system by applying a suitable component mode synthesis approach. Subsequently, this allows the application of appropriate numerical methodologies for predicting response spectra of the nonlinear models to periodic road excitation. Results obtained by direct integration of the equations of motion are also presented. The accuracy and validity of the applied methodology is verified by comparison with results obtained for the original models. The frequency ranges examined are useful for studies referring to both ride and acoustics response of the vehicle.
Knowledge Sharing Between Designers and Accidentologists for the Development of Road Safety Systems
Authors: Ben Ahmed Walid , Mekhilef Mounib , Bigand Michel , Page Yves
Published: June 2008

Road Safety System development is complex task, which requires the collaboration between designers and accidentologists. However, designers and accidentologists do not share the same viewpoints, neither the same models to analyze an accident, nor the same technical language. This makes their communication a complex task in a design process. Accident Scenario is recognized as a powerful communication tool between designers and accidentologists. Nevertheless, an accident scenario has to be presented in a way that both designers and accidentologists can understand and use. To address this issue, we use the systemic approach (a complex system modeling approach) to develop a new methodology allowing constructing multi-view accident scenarios.
Nonlinear Dynamics of Interconnected Structures: An Application to DNA Dynamics
Authors: Shukla Amit
Published: June 2008

Nonlinear dynamics of DNA base-pairs is essential in many of the genetic features and functions of the molecule. The motion of the base-pair is influenced by the nonlinear potential between the two nucleotides as well as the adjacent base-pairs. In this paper nonlinear dynamics of the base-pairs is investigated. A single degree-of-freedom model for the base-pair dynamics as proposed by Peyrard-Bishop-Dauxois is analyzed. First a single base-pair dynamics is investigated using perturbation method. Then a three base-pair model is numerically investigated to understand the nonlinear response of the system to a harmonic excitation. Finally, it is also shown that the effect of interconnection can be minimized by selecting the environment surrounding the DNA molecule.
Motion and Vibration Control of a Flexible Transportation System Used Piezoelectric Films as Sensor for Vibration Detection
Authors: Nishikiori Masato , Watanabe Toru , Seto Kazuto
Published: June 2008

This paper deals with motion and multi-modes of vibration control of a flexible transportation system. In order to reduce a settling time from one position to another one, the vibration control is remarkably important on the transportation system. Since transportation system moves long distance, no limit in the measuring range of the sensor is required. For the purpose, piezoelectric films pasted on flexible structures are used as the point sensor to detect vibrations. To control the first two vibration modes, the reduced-order physical modeling method proposed by authors is applied and the control system is designed by LQ control approach. Control experiments demonstrate that the settling time is well shortening by controlling many-modes of vibration in addition to motion.
Modelling Autoparametric Resonance in a Coupled Pendulum Oscillator System Using Hybrid Testing
Authors: Gonzalez-Buelga Alicia , Wagg David
Published: June 2008

Hybrid testing is a novel form of system modelling which consists of a model which is part numerical, part experimental. This form of testing has applications in the automotive, aerospace and construction industry where it is being developed as an advanced form of component testing. In this paper we present results from a hybrid numerical-experimental system of a coupled pendulum oscillator system. This system is a good test case example for developing the science of hybrid testing because it has clearly defined linear and nonlinear parts. We show how such a system can be modeled by coupling an experimental pendulum with a numerical oscillator. We include discussion on delay effects, control techniques, accuracy and stability of the system.
A Study of Errors Induced by Decoupling Approximation in Damped Linear Vibratory Systems
Authors: Ajavakom N. , Ma F.
Published: June 2008

It is well known that an undamped linear vibratory system can be decoupled through transformation to principal coordinates. In the presence of damping, coordinate decoupling occurs only if the system is classically damped. Upon modal transformation, the system generally remains coupled by the off-diagonal elements of its modal damping matrix. A common approximation in the analysis of nonclassically damped systems is to ignore the off-diagonal elements of the modal damping matrix, which is equivalent to neglecting coupling of the principal coordinates. This procedure is termed the decoupling approximation. Intuitively, the errors of decoupling approximation should be small if the off-diagonal elements of the modal damping matrix are small. Contrary to this widely accepted belief, an example is provided to demonstrate that this criterion is not sufficient for decoupling approximation. In fact, coupling effect can even increase as the off-diagonal elements of the modal damping matrix decrease in magnitude. Discussion and explanation are provided as to why the errors increase when the modal damping matrix becomes increasingly diagonal.
DesigNAR: An Intelligent Design Assistant Based on C-K Design Theory
Authors: Kazakci Akin O.
Published: June 2008

We present a personal design assistant, DesigNAR, aiming at actively supporting designing. The assistant cooperate with the designer by observing the external design representation on which he is working, by making suggestions to him on how to further elaborate this representation and adapting its (suggestion) behaviour according to the designer’s reactions to those suggestions. DesigNAR implements a Non-Axiomatic Reasoning system on fluid concept representations. This enables DesigNAR to be a situated, creative and adaptive design agent using a constructive memory and grounding of concepts. As discussed in the paper, these features make DesigNAR compatible with the C-K design theory and its C/K/E extension.
Rotating Mistuned Bladed Disk Assembly Dynamic Response Prediction Using Component Mode Synthesis Methods With Interface Modes
Authors: Duvauchelle Francois , Tran Duc-Minh , Ohayon Roger
Published: June 2008

Finite element-based reduced order methods are presented with application to the prediction of rotating mistuned bladed disk forced response. These methods have already been applied to tuned non-rotating models having cyclic symmetry. The aim is to reduce significantly the number of interface co-ordinates, which can be very important in classical component mode synthesis methods. The approach is based on the use of the interface modes which result from a static condensation of the whole structure on the whole interface. A first implementation of this procedure and numerical results are presented.
Experiment of Oil-Film Whirl in Rotor System and Wavelet Fractal Analyses
Authors: Han Qing Kai , Yao Hong Liang , Zhang Zhi Wei , Wen Bang Chun
Published: June 2008

An oil-film whirl experiment is carried out in a rotor test rig and some nonlinear analyses are achieved in the paper. Firstly, the experiment schemes for measuring oil-whirl of a rotor system are introduced. The shaft vibrations are measured both in stable rotating process and running up and coast down. And then, the detailed signals of level 3, reconstructed by wavelet transform, representing the oil-film whirl motions are analyzed. At last, a wavelet fractal method is proposed, based on wavelet package transform and fractal geometry theory, and the correlative dimensions of signals in every frequency bands are calculated. This method describes the chaotic properties of the oil-film whirl vibration well, and wavelet fractals prove to be more effective than any other nonlinear parameters of the corresponding original shaft vibration signals.
Dynamic Analysis of a Torsional MEMS Scanner Mirror: Part 1 — Disturbance Analysis Framework
Authors: Meral Faik Can , Basdogan Ipek
Published: June 2008

Future optical micro systems such as Micro Electro Mechanical Systems (MEMS) scanners and micro-mirrors will extend the resolution and sensitivity offered by their predecessors. These systems face the challenge of achieving nanometer precision subjected to various disturbances. Predicting the performance of such systems early in the design process can significantly impact the design cost and also improve the quality of the design. Our approach aims to predict the performance of such systems under various disturbance sources and develop a generalized design approach for MEMS structures. In this study, we used ANSYS for modeling and analysis of a torsional MEMS scanner mirror. ANSYS modal analysis results, which are eigenvalues (natural frequencies) and eigenvectors (modeshapes), are used to obtain the state space representation of the mirror. The state space model of the scanner mirror was reduced using various reduction techniques to eliminate the states that are insignificant for the transfer functions of interest. The results of these techniques were compared to obtain the best approach to obtain a lower order model that still contains all of the relevant dynamics of the original model. After the model size is reduced significantly, a disturbance analysis is performed using Lyapunov approach to obtain root-mean-square (RMS) values of the mirror rotation angle under the effect of a disturbance torque. The Lyapunov approach results were validated using a time domain analysis.
Sensitivity Analysis of an Information Maximization Approach to the Blind Separation of the Vibration Responses of Defective Rolling Element Bearings
Authors: Yiakopoulos C. , Antoniadis I.
Published: June 2008

Vibration response of rotating machines is typically mixed and corrupted by a variety of interfering sources and noise, leading to the necessity for the isolation of the useful signal components. A relevant frequently encountered industrial case is the need for the separation of the vibration responses of the same type of bearings inside the same machine. For this purpose, a Blind Source Separation procedure has been successfully applied, based on the maximization of the information transferred in a neural network structure. Thus, a key element for the success of the proposed procedure is the non-linear function used in this single layer Neural Network structure. However, since the vibration response of defective rolling element bearings is characterized by signals with super-Gaussian distributions, a sensitivity analysis of this non-linear function is necessary. First, this analysis is performed in a set of numerical experiments, based on dynamic models of defective bearings. Finally, the same analysis is applied in an experimental test rig.
Synthesis of a Limited-Bandwidth Fractional Differentiator Made in Hydropneumatic Technology
Authors: Serrier Pascal , Moreau Xavier , Oustaloup Alain
Published: June 2008

In a vibration isolation context, fractional derivative can be used to design suspensions which allow to obtain similar performances in spite of parameters uncertainties. This paper presents the synthesis and the achievement of a CRONE suspension. A CRONE suspension is synthesised using the CRONE control methodology. Its transfer function is a limited bandwidth fractional differentiator. After the formulation of vibration isolation problems as control law synthesis problems, a method to determine the technological parameters of a CRONE suspension is proposed and is applied to a CRONE hydraulic test bench. A parallel arrangement of dissipative and capacitive components and a gamma arrangement are compared. They lead to the same unusual performances: the stability degree robustness and the rapidity robustness.
Low Cost Demonstrator as a Mean for Rapid Product Realization With an Electric Motorcycle Application
Authors: Hallberg Peter , Krus Petter , Austrin Lars
Published: June 2008

During the last decade, digital prototyping has become a natural part of any industrial project dealing with product development. The reasons for this differ, but the two most obvious is time saving aspects and the amount of cost effectiveness achieved when replacing the physical prototype with the cheaper digital. Time and cost are equally, or even more critical in academic projects. This paper describes the usage of a low cost demonstrator as a mean to reduce both time and cost during a product development project course as well as to guarantee educational quality. The paper also discusses the reason for using demonstrators in an industrial environment. When large product development project courses are given at educational engineering programs, they often strive for imitating a real industrial situation, trying to include all the phases and aspects of product realization. Time is of course critical in both environments, industrial and academic, but for slightly different reasons. A typical industrial project may run over several years while a large educational project’s duration is counted in months. Thus, if the course tutor wants to simulate the whole product development process, within the same project course, there are needs for means that may speed up the project without spoiling the educational message as well as the industrial authenticity.
Generation of Alternative Feature Representations and Feature Precedence Relations for Feature-Based Process Planning
Authors: Sormaz Dusan N. , Arumugam Jaikumar
Published: June 2008

This work deals with the analysis and transfer of design information, expressed in terms of features, from feature-based CAD models to CAPP systems in order to perform process planning. In this paper, we present an integrated system that retrieves design information from a feature-based CAD model, performs feature mapping, identifies interactions between features, generates alternative feature representations and feature precedence relations. The alternative feature representations provides the process planner with more flexibility in terms of process selection and are shown in the form of an AND-OR graph. The feature precedence relations, represented as a directed feature precedence network, assist the process planner in its process sequencing tasks. Feature mapping involves the mapping of design features into equivalent valid machining features. Feature interactions are identified by analyzing part geometry for face adjacency and hence feature adjacency. The interacting features are then analyzed to identify possible alternative feature representations and feature precedence relationships. Procedures for the identification of feature interactions and determination of alternative feature representations and feature precedence relationships are provided. The generated AND-OR graph and the feature precedence network seeks to aid CAPP systems in process sequence generation and serve as a vital step for the integration of design and planning systems.
Aircraft Engine Structural Rotor-Stator Modal Interaction
Authors: Legrand Mathias , Roques Se´bastien , Peseux Bernard , Pierre Christophe
Published: June 2008

In modern turbo machines such as aircraft jet engines, contact between the casing and bladed disk may occur through a variety of mechanisms: coincidence of vibration modes, thermal deformation of the casing, rotor imbalance, etc. These nonlinear interactions may result in severe damage to both structures and it is important to understand the physical mechanisms that cause them and the circumstances under which they occur. In this study, we focus on the phenomenon of interaction caused by modal coincidence. A simple two-dimensional model of the casing and bladed disk structures is introduced in order to predict the occurrence of the interaction phenomenon versus the rotation speed of the rotor. Each structure is represented in terms of its two k-nodal diameter vibration modes, which are characteristic of axi-symmetric structures and allow for travelling wave motions that may interact through direct contact. The equations of motion are solved using an explicit time integration scheme in conjunction with the Lagrange multiplier method where friction is considered. Results of the numerical tool and theory show good agreement in the prediction of rotational speed to be avoided. To conclude, the mathematical statements of a multi-frequency domain-method are proposed. This method is to be used to circumvent numerical issues inherent to time-marching procedures.
Integrated Framework for Design Optimization Under Aleatory and/or Epistemic Uncertainties Using Adaptive-Loop Method
Authors: Youn Byeng D.
Published: June 2008

In last two decades, significant attentions have been paid to develop design optimization methodologies under various uncertainties: reliability-based design optimization (RBDO), possibility-based design optimization (PBDO), etc. As a result, a variety of methods of uncertainty-based design optimization have been proposed and are mainly catagorized as: parallel-loop method, serial-loop method, and single-loop method. It has been reported that each method has its own strong and weak points. Thus, this paper attempts to understand various methods better, and proposes to develop an integrated framework for uncertainty-based design optimization. In short, the integrated design framework timely involves three phases (deterministic design optimization, parallel-loop method, single-loop method) to maximize numerical efficiency without losing computational stability and accuracy in the process of uncertainty-based design optimization. While the parallel-loop method maintains numerical stability well with a minimal computation, deterministic design optimization and single-loop method will improve numerical efficiency at the beginning and end of uncertainty-based design optimization. Thus, the proposed method is called adaptive-loop method. It will be shown that integrated framework using the proposed method is applicable for various design optimization methodologies under aleatory or epistemic uncertainties, such as RBDO, PBDO, etc. Examples are used to demonstrate the effectiveness of integrated framework using the adaptive-loop method in terms of numerical efficiency.
A Virtual Model for Aluminum Hot Forging Using an Artificial Neural Network Material Model Within Finite Element Analysis
Authors: Kessler B. Scott , El-Gizawy A. Sherif
Published: June 2008

The accuracy of a finite element model for design and analysis of a metal forging operation is limited by the incorporated material model’s ability to predict deformation behavior over a wide range of operating conditions. Current rheological models prove deficient in several respects due to the difficulty in establishing complicated relations between many parameters. More recently, artificial neural networks (ANN) have been suggested as an effective means to overcome these difficulties. In the present work, a previously developed ANN with the ability to determine flow stresses based on strain, strain rate, and temperature is incorporated with finite element code. Utilizing this linked approach, a preliminary model for forging an aluminum wheel is developed. This novel method, along with a conventional approach, is then measured against the forging process as it is currently performed in actual production.
A Technique for Assessing Tire Forces in a Vehicle Moving Along a Harmonic Profile and Its Application to Low-Speed Testing
Authors: Pesterev Alexander V. , Bergman Lawrence A. , Tan Chin An
Published: June 2008

The paper is concerned with the assessment of dynamic tire forces that arise when a vehicle traverses a road with a harmonic profile. In this case, solutions of all equations are found analytically. The technique developed is not specific to a particular linear vehicle model, which is represented by its mass, stiffness, and damping matrices. A factored representation of the vector of the tire forces as the product of a matrix and a vector, where both the matrix and the vector are functions of only one variable, is derived. The matrix is constructed either by the mathematical model of the vehicle or by results of special tests on the vehicle at several values of speed. The vector is given by an explicit formula and requires knowledge of only the wheelbase distances. An application of the technique discussed to the so-called low-speed testing is discussed. It is shown that, in spite of the wheelbase filtering phenomenon, it is possible to replace testing vehicles at highway speeds by tests at artificially low speeds. The results of the latter tests can then be recalculated into those corresponding to the highway conditions. The discussions are illustrated by numerical examples.
Design for Product-Embedded Disassembly
Authors: Takeuchi Shingo , Saitou Kazuhiro
Published: June 2008

This paper presents a computational method for designing assemblies with a built-in disassembly pathway that maximizes the profit of disassembly while satisfying regulatory requirements for component retrieval. Given component revenues and components to be retrieved, the method simultaneously determines the spatial configurations of components and locator features on the components, such that the product can be disassembled in the most profitable sequence, via a domino-like “self-disassembly” process triggered by the removal of one or a few fasteners. The problem is posed as optimization and a multi-objective genetic algorithm is utilized to search for Pareto-optimal designs in terms of three objectives: 1) the satisfaction of distance specification among components, 2) the efficient use of locator features on components, and 3) the profit of overall disassembly process under the regulatory requirements. A case study with different costs for removing fasteners demonstrates the effectiveness of the method in generating design alternatives under various disassembly scenarios.
Vibration Isolation of Precision Payloads for Aerial Vehicles Using Magnetorheological Isolators
Authors: Choi Young-Tai , Brigley Mikel , Wereley Norman M.
Published: June 2008

This study addresses the application of MR (magnetorheological) isolators to vibration isolation of precision payloads for aerial vehicles. To this end, a precision payload in an aerial vehicle is modeled as a six-degree-of-freedom (DOF) lumped parameter model of a sensor assembly. An MR isolator is modeled as a 3-DOF passive spring-damping element and a 3-DOF semi-active yield force due to the yield stress of an MR fluid. Three MR isolators are configured with equal installation angles between the precision payload and the base structure in the aerial vehicle. The governing equations of motion for the MR vibration isolation system of the precision payload for the aerial vehicle are derived and then key parameters of the MR isolators, such as stiffness, damping, and isolator orientation, are determined via a global optimization method. The simulated response of the passive MR vibration isolation system with no magnetic field control input and constant magnetic field control input are presented and analyzed under different excitation conditions. To improve the passive MR vibration isolation performance, a linear quadratic Gaussian (LQG) control algorithm is designed. Finally, simulated responses of the semi-active MR vibration isolation performance using LQG control are evaluated and compared with those of passive (zero or constant field) MR vibration isolation systems.
Systematic Decision Support for Engineering Change Management in PLM
Authors: Joshi Nikhil , Ameri Farhad , Dutta Debasish
Published: June 2008

Engineering Change Management (ECM) is an important component of PLM. ECM modules in current PLM solutions conform to the industry-standard CMII closed-loop change model. They provide customised forms and pre-defined workflows for creating and processing change requests, change orders, etc. Evaluating the effects of the proposed Engineering Change on manufacturing processes, BOM, lead times, inventory, etc., usually form tasks in this generic workflow. However, each change has different downstream effects, which themselves lead to further changes that may not be evident. Identifying these impacts requires considerable experience and expertise. This paper addresses the need for automated tools to assist this process. The approach involves dynamic creation of workflow tasks for evaluating cascaded effects of any change using a predefined industry specific knowledge base. The process is further enhanced by prioritising the evaluation of effects based on experience generated by past engineering changes.
Intersections With Validated Error Bounds for Building Interval Solid Models
Authors: Mukundan Harish , Ko Kwang Hee , Patrikalakis Nicholas M.
Published: June 2008

Interval arithmetic has been considered as a step forward to counter numerical robustness problem in geometric and solid modeling. The interval arithmetic boundary representation (B-rep) scheme was developed to tackle this problem. In constructing an interval B-rep solid, robust and efficient computation of intersections between the bounding surfaces of the solid is a critical issue. To address this problem, a marching method based on a validated interval ordinary differential equation (ODE) solver was proposed, motivated by its potential for the interval B-rep model construction. In this paper, we concentrate on the issue of error control in model space using the validated ODE solver, and further explain that the validated ODE solver can be used in the construction of an interval B-rep solid model using such an error control.