bluuebunny/crossref_metadata_2025 huggingface dataset:
The Interdisciplinary Design Engineering Department: A Systems View, a Design Focus and Customizable Interdisciplinary Tracks
Authors: Stone Robert B. , Hubing Nancy , Fannin Ron , Flori Ralph
Published: June 2008

Graduates of traditional engineering programs are called on to fill a myriad of interdisciplinary design careers that are increasingly different than historical engineering jobs. These careers focus on complex problems and the importance of solving them quickly in order to be successful corporately and nationally, and demand the use of teams of interdisciplinary, people-and-process-intuitive professionals with special technical skills in engineering systems and engineering design. The students who will be needed to fill these jobs are different as well. They have grown up with computers, have seen that emerging technologies occur at the interface or outside the boundaries of traditional disciplines and are diverse in many ways beyond gender and ethnicity. National trends show smaller percentages of high school graduates are now choosing careers in engineering. In this paper we report on a fresh and innovative type of engineering department that will offer programs carefully designed to augment traditional departments and programs while providing the underpinning engineering design and systems skills to attract and create the engineers needed today. This new engineering department, called Interdisciplinary Design Engineering, will produce graduates who are experts in the process of designing engineering systems.
Frequency Response Analysis of Piecewise Nonlinear Vibration Isolator
Authors: Stahl Patrick , Nakhaie Jazar G.
Published: June 2008

Non-smooth piecewise functional isolators are smart passive vibration isolators that can provide effective isolation for high frequency/low amplitude excitation by introducing a soft primary suspension, and by preventing a high relative displacement in low frequency/high amplitude excitation by introducing a relatively damped secondary suspension. In this investigation a linear secondary suspension is attached to a nonlinear primary suspension. The primary is assumed to be nonlinear to model the inherent nonlinearities involved in real suspensions. However, the secondary suspension comes into action only during a short period of time, and in mall domain around resonance. Therefore, a linear assumption for the secondary suspension is reasonable. The dynamic behavior of the system subject to a harmonic base excitation has been analyzed utilizing the analytic results derived by applying the averaging method. The analytic results match very well in the transition between the two suspensions. A sensitivity analysis has shown the effect of varying dynamic parameters in the steady state behavior of the system.
Embedded Fault Tree Logic Implementation Based on Complex Programmable Logic Device
Authors: Yuguo Sun , Jin Chen
Published: June 2008

To meet the requirements of an embedded mechanical fault diagnosis system development, a fault tree implementation and dynamic modification method based on CPLD (Complex Programmable Logic Device) is investigated experimentally. The mechanism of fault tree logic calculation in the CPLD chip is presented. The fault logic tree is modeled by VHDL (VHSIC Hardware Description Language) and logic graphic, respectively. The effects of the bottom events on the logic result are simulated in Max + plus II platform. The fault tree logic is downloaded into the EPM7064SLC44-10 chip by ISP (In System Programmable) technology. And evaluated in terms of power consumption, system’s volume and design flexibility. The study results show that CPLD is suit to the fault tree’s construction, contributed by the chip’s outstanding ISP function and programmable logic function. And the fault tree logic synthesis and the chip resource optimization need to be further investigated.
Enhanced Sequential Optimization and Reliability Assessment Method for Changing Design Variance
Authors: Yin Xiaolei , Chen Wei
Published: June 2008

The Sequential Optimization and Reliability Assessment (SORA) method is a single loop method containing a sequence of cycles of decoupled deterministic optimization and reliability assessment for improving the efficiency of probabilistic optimization. However, the original SORA method as well as some other existing single loop methods is not efficient for solving problems with changing variance. In this paper, to enhance the SORA method, three formulations are proposed by taking the effect of changing variance into account. These formulations are distinguished by the different strategies of Inverse Most Probable Point (IMPP) approximation. Mathematical examples and a pressure vessel design problem are used to test and compare the effectiveness of the proposed formulations. The “Direct Linear Estimation Formulation” is shown to be the most effective and efficient approach for dealing with problems with changing variance. The gained insight can be extended and utilized to other optimization strategies that require MPP or IMPP estimations.
Thermal Design and Characteristics of Thermal Distribution in Process Chamber
Authors: Zheng Y. H. , Amano R. S.
Published: June 2008

Thermal distribution has a critical effect on prototyping accuracy in rapid prototyping and rapid manufacturing. Any uneven thermal distribution in the work bed of the prototyping machine process chamber will result in product distortion. In order to optimize the thermal distribution enhance product accuracy of product and guide future design efforts, a full understanding is necessary, of the characteristics of thermal distribution in the process chamber. This study focuses on how to design and control thermal distribution in the process chamber due to natural convection with experimental and numerical thermal model. For optimal thermal design, the computational fluid mechanics (CFD) approach is one of the most powerful tools. Both experimental and numerical studies of six design configurations for different source heater locations and baffle configurations are presented in this paper.
Design Navigator System: A Case Study in Improving Product Development Through Improved Information Management
Authors: Karnik M. V. , Gupta S. K. , Anand D. K. , Valenta F. J. , Wexler I. A.
Published: June 2008

This paper provides an overview of the Design Navigator system being developed for the Naval Surface Warfare Center, Indian Head. This system addresses the following three information management needs. First, it captures all the relevant information being generated during the product development process in a computer-interpretable form. This eliminates information loss from the design process. Second, it builds fully interconnected information models. Thus ensuring full connectivity between requirements and specifications to various parts and assemblies in the design. Third, it offers multiple modes of searching and retrieving design information in an intuitive and convenient manner. By supporting functionality-based queries, change-based queries, geometry-based queries, and visual navigation of the entire product database, the Design Navigator system is expected to offer maximum flexibility and power to the designers to meet their diverse information retrieval needs.
Adaptive Modeling of Laser Powder Deposition Process for Control and Monitoring Application
Authors: Durali Mohammad , Fathi Alireza , Khajepour Amir , Toyserkani Ehsan
Published: June 2008

Laser Powder Deposition technique is an advanced production method with many applications. Despite this fact, reliable and accurate control schemes have not yet fully developed for this method. This article presents method for in time identification of the process for modeling and adaptation of proper control strategy. ARMAX structure is chosen for system model. Recursive least square method and Kalman Filter methods are adopted for system identification, and their performance are compared. Experimental data was used for system identification, and proper filtering schemes are devised here for noise elimination and increased estimation results. It was concluded that although both methods yield efficient performance and accurate results, Kalman Filter method gives better results in parameter estimations. The comparison of the results shows that this method can be used very efficiently in control and monitoring of Laser Powder Deposition process.
A Divide-and-Conquer Algorithm for Machining Feature Recognition Over Network
Authors: Gao Shuming , Zhou Guangping , Liu Yusheng , Chen Xiang
Published: June 2008

In this paper, a divide-and-conquer algorithm for machining feature recognition over network is presented. The algorithm consists of three steps. First, decompose the part and its stock into a number of sub-objects in the client and transfer the sub-objects to the server one by one. Meanwhile, perform machining feature recognition on each sub-object using the MCSG based approach in the server in parallel. Finally, generate the machining feature model of the part by synthesizing all the machining features including decomposed features recognized from all the sub-objects and send it back to the client. With divide-and-conquer and parallel computing, the algorithm is able to decrease the delay of transferring a complex CAD model over network and improve the capability of handling complex parts. Implementation details are included and some test results are given.
On the Rarefied Gas Flow in Pipes
Authors: Djordjevic Vladan D.
Published: June 2008

Rarefied gas flow in a pipe is treated in the paper by modeling the slip boundary condition by means of a fractional derivative. At that the order of the derivative is conveniently chosen to be a function of the average value of the Knudsen number so that the entire Knudsen number range, from continuum flow to free molecular flow, is covered. Very good agreement with the solutions of linearized Boltzmann equation is achieved. The paper represents a natural extension of the work of the same author on the rarefied micro channel flow, published earlier.
Recursive Algorithm Based on Canonical Momenta for Forward Dynamics of Multibody Systems: Numerical Results
Authors: Naudet Joris , Lefeber Dirk
Published: June 2008

In this paper, a recursive O(n) method to obtain a set of Hamiltonian equations for open-loop and constrained multibody system is briefly discussed. The method is then used to perform a numerical comparison of acceleration based and canonical momenta based equations of motion. A relatively simple example consisting of a biped during double support phase is used for that purpose. While no significant difference in efficiency is found when using a fixed step numerical integration method, the Hamiltonian equations perform considerably better when using an adaptive method. This is at least the case when the error control is applied straightforwardly. Both methods can be made equally efficient by removing the error control on the velocities for the acceleration based equations.
On Response Prediction of Degrading Structures
Authors: Ng C. H. , Ajavakom N. , Ma F.
Published: June 2008

All structures degrade when acted upon by cyclic forces associated with earthquakes, high winds, and sea waves. Identification and prediction of degradation is thus a problem of considerable practical significance in the field of engineering mechanics. Under cyclic excitations, system degradation manifests itself in the evolution of the associated hysteresis loops. In this paper, a robust identification algorithm is devised to generate hysteretic models of a deteriorating structure from its experimental load-displacement traces. This algorithm is based upon the generalized Bouc-Wen model and the latest theory of differential evolution, streamlined through global sensitivity analysis. It can account for strength degradation, stiffness degradation, and pinching characteristics in the evolution of hysteretic traces, whereby earlier studies in parametric identification of hysteresis are extended. In addition, it is shown experimentally that a hysteretic model obtained by identification can be used to predict the future performance of a degrading structure. Prediction of degradation through identification is a brute-force approach that offers a close representation of reality. There is not any method based upon the fundamental postulates of mechanics that can predict the response of a degrading structure well beyond its linear range.
Multibody Simulation Formulations in Fault Diagnosis of a Reel
Authors: Korkealaakso Pasi , Rouvinen Asko , Mikkola Aki
Published: June 2008

In order to improve the recognition of faulty situations, the model-based fault diagnosis can be used together with signal processing methods. In this study, faults and abnormalities of a reel is studied by employing the multibody simulation approach. The reel under consideration consists of a number of subsystems including hydraulics, electrical drives and mechanical parts, which are coupled by joints, friction forces and contact forces. Using the multibody simulation approach, the complete model of the reel can be obtained by coupling different subsystems together. Three well-known multibody formulations, a method of Lagrange multipliers, an Augmented Lagrangian method and a method based on projection matrix R, are briefly described and compared in order to find out the most efficient method for simulating the studied reel. It is noteworthy, that the method based on an Augmented Lagrangian formulation is also capable of real-time fault diagnosis of a reel.
Design of Brewery Pasteurization Method by High Pressure Carbon Dioxide
Authors: Lee S. , Amano R. S.
Published: June 2008

The compressed CO2 was supplied from the CO2 cylinder to the steel vessel containing yeast-water mixture until the pressure inside the steel vessel reached a desired pressure level. The steel vessel was kept at the prescribed pressure level during the treatment period. After the treatment, the pressure inside the vessel was released to the atmospheric pressure within the evacuation time by controlling the relief control valve. The sterilization effect was evaluated by vial counting the treated sample taken from the steel vessel. Several experiments have been performed varying each factor such as the total treatment time, the evacuation time and the applied pressure. As a result, it was verified that these factors are strongly related to the sterilization effect. In addition, it was observed that increase of the treatment time could enhance the concentration rate of CO2 in the mixture. Furthermore, it was concluded that fast depressurizing rapidly expanded CO2 penetrated into each yeast cell. Also, the experimental results showed that when treatment time is longer, the pressure becomes higher, and the evacuation time is shorter, thus, a better sterilizing effect was obtained. Contrary to the results above, both the treatment time and the evacuation time rarely affected sterilization effect under supercritical condition. By adopting Supercritical condition, a desirable result could be achieved with shorter treatment and longer evacuation time. Thus, as long as supercritical condition is adopted for test, either fast evacuation time or long treatment time is not essential any more.
A Methodology to Support Product Family Redesign Using Genetic Algorithm and Commonality Indices
Authors: Thevenot Henri J. , Nanda Jyotirmaya , Simpson Timothy W.
Published: June 2008

Many of today’s manufacturing companies are using platform-based product development to realize families of products with sufficient variety to meet customers’ demands while keeping costs relatively low. The challenge when designing or redesigning a product family is in resolving the tradeoff between product commonality and distinctiveness. Several methodologies have been proposed to redesign existing product families; however, a problem with most of these methods is that they require a considerable amount of information that is not often readily available, and hence their use has been limited. In this research, we propose a methodology to help designers during product family redesign. This methodology is based on the use of a genetic algorithm and commonality indices - metrics to assess the level of commonality within a product family. Unlike most other research in which the redesign of a product family is the result of many human computations, the proposed methodology reduces human intervention and improves accuracy, repeatability, and robustness of the results. Moreover, it is based on data that is relatively easy to acquire. As an example, a family of computer mice is analyzed using the Product Line Commonality Index. Recommendations are given at the product family level (assessment of the overall design of the product family), and at the component level (which components to redesign and how to redesign them). The methodology provides a systematic methodology for product family redesign.
Computational Algorithms for a Damage-Coupled Cyclic Viscoplasticity Material Model
Authors: Zhao Aihong A. (Rachel) , Chow C. L.
Published: June 2008

The primary objective of the investigation is to develop efficient and robust computational schemes for a damage-coupled cyclic thermoviscoplasticity model for solder material. Three constitutive integration algorithms, Euler, modified Euler and semi-implicit algorithm for the model are examined. The three algorithms for the model are coded in the commercial finite element (FE) code ABAQUS (version 6.21) via the user-defined material subroutine UMAT. Two single-step algorithms of the substep scheme are applied for the modified Euler algorithm to control the error in the integration of constitutive laws. A semi-empirical formulation is established for an adaptive time stepping algorithm that is based on the Euler algorithm. Single-element, miniature specimen and notched specimen simulations have been conducted to compare with the test results, which include monotonic tensile, creep and fatigue tests of 63Sn-37Pb solder. It is observed that the explicit algorithm consistently requires much less CPU time than others. The modified Euler algorithm has shown on the other hand to be not only efficient but also accurate. The semi-implicit algorithm yields accurate solution. It is worth noting that the method is also effective when an appropriate integration scheme is chosen.
Stabilization of a Buckled Beam by High-Frequency Excitation: Linear Analysis and Experiments
Authors: Tsumoto Koji , Yabuno Hiroshi , Aoshima Nobuharu
Published: June 2008

Beam is one of the fundamental elements in complex structures. It is very significant to clarify its stability under the various circumstances. In particular, the buckling phenomenon, which is characterized as a pitchfork bifurcation, has accepted much interest by many researchers. In this paper, we propose a stabilization control method for the first-mode buckling phenomenon in the clamped-clamped beam without feedback control. We analyze the stability of a buckled beam under high frequency excitation in linear theory. It is theoretically clarified and experimentally that the high-frequency excitation shifts the bifurcation point (the critical compressive force) and prevents the beam buckling.
A Configurable Module Based Technology for Complex Engineering Process Management Systems
Authors: Song Bin , Li Zenzhi , Ao Yintai , Xiao Xuejian , Zhou Hong , Lu W. F.
Published: June 2008

An integrated end-to-end lifecycle engineering process management system is deemed critical to boost the manageability, efficiency and responsiveness of an engineering enterprise. The challenge lies in the realization of such a system that is flexible and scalable. To overcome the challenge, a configurable module based system technology is developed to simplify the realization of a complex process management system and to offer the system a high level of flexibility and scalability. The technology is based on the belief that a complex process management system can be built by a set of static and process-based function modules. Each of the function modules consists of a set of categorized elements to meet the desired functional requirements. These categorized elements can be extracted into a unified process model upon which a configurable modular can be developed. The modular can be configured into a desired function module with specific functional requirements. The assignment of the function modules to the specific roles at the lifecycle processes forms a system. The technology has been successfully applied in a company specializing in make-to-order operations.
An Applied Form of Kane’s Equations of Motions
Authors: Pishkenari Hossein Nejat , Gaskarimahalle Amir Lotfi , Oskouei Seyed Babak Ghaemi , Meghdari Ali
Published: June 2008

In this paper we have presented a new form of Kane’s equations. This new form is expressed in the matrix form with the components of partial derivatives of linear and angular velocities relative to the generalized speeds and generalized coordinates. The number of obtained equations is equal to the number of degrees of freedom represented in a closed form. Also the equations can be rearranged to appear only one of the time derivatives of generalized speeds in each equation. This form is appropriate especially when one intends to derive equations recursively. Hence in addition to the simplicity, the amount of calculations is noticeably reduced and also can be used in a control unit.
Vehicle Crashworthiness Design Via a Surrogate Model Ensemble and a Co-Evolutionary Genetic Algorithm
Authors: Hamza Karim , Saitou Kazuhiro
Published: June 2008

This paper presents a new method for designing vehicle structures for crashworthiness using surrogate models and a genetic algorithm. Inspired by the classifier ensemble approaches in pattern recognition, the method estimates the crash performance of a candidate design based on an ensemble of surrogate models constructed from the different sets of samples of finite element analyses. Multiple sub-populations of candidate designs are evolved, in a co-evolutionary fashion, to minimize the different aggregates of the outputs of the surrogate models in the ensemble, as well as the raw output of each surrogate. With the same sample size of finite element analyses, it is expected the method can provide wider ranges potentially high-performance designs than the conventional methods that employ a single surrogate model, by effectively compensating the errors associated with individual surrogate models. Two case studies on simplified and full vehicle models subject to full-overlap frontal crash conditions are presented for demonstration.
An Analytic Study on Controlling Duffing Chaos in Amplitude Domain and in Frequency Domain
Authors: Peng Jie-Hua , Tang Jia-Shi
Published: June 2008

An analytical study on the chaos control of Duffing oscillator both in amplitude domain and in frequency domain is made in this paper. By means of the combined action of harmonically parametrical perturbation and forcing perturbation and suitably adjusting the parameters of perturbations, the chaotic motion of Duffing oscillator can be effectively controlled in a small region in the parametric space. We find that, in the amplitude domain, the chaotic motion exists only in the region where the ratio of the amplitudes of the perturbations is large than critical ratio, and, in the frequency domain, the chaotic motion exists only in a limited region where the frequency of perturbation is lower than superior frequency limit and larger than inferior frequency limit. The inferior frequency limit and superior frequency limit of chaotic region are discovered and determined firstly. An analytical expression of the critical ration of the amplitudes of forcing and parametrical perturbations is established.
Efficient Computation of Stability Charts for Linear Time Delay Systems
Authors: Breda Dimitri , Maset Stefano , Vermiglio Rossana
Published: June 2008

A new efficient algorithm for the computation of the stability chart of linear time delay systems is proposed and tested on several examples. The stability chart is obtained by investigating the 2d-parameter space by a first coarse square grid which is then adaptively refined by triangulation to match the desired tolerance. This leads to a considerable reduction in computational cost with respect to investigate a uniform fine square grid. Stability of each point is determined by approximating the rightmost characteristic root real part via a numerical scheme recently developed by the authors and based on pseudospectral differencing methods. A Matlab code is included in appendix.
Stabilizing Effects of Speed Fluctuations on the Dynamic Response of Rolling Element Bearings With Radial Clearances
Authors: Lioulios A. N. , Antoniadis I. A.
Published: June 2008

A horizontal balanced rotor supported on ball bearings with radial internal clearance, subjected to rotational speed fluctuations is modeled. The dynamic model takes under consideration contact forces derived by the hertzian theory of elasticity between the balls and the races, the effect of varying compliance, the internal radial clearance and the rotor’s speed fluctuations. The effect of variation in speed fluctuations is examined for periodic, unstable periodic and chaotic responses with the use of frequency distributions, higher order Poincare maps, and Lyapunov exponents. All results presented show a dominant stabilization effect of the speed fluctuations to the system behavior. From the analysis performed, it is concluded that even a minimum fluctuation of the rotor speed may result to major changes of the system dynamics, indicating that speed fluctuations of the rotor are a governing parameter to the dynamic behavior of the system.
Observer Based Adaptive Backstepping Velocity Controller for a Flexible Mechanism of a PMLSM
Authors: Hirvonen Markus , Pyrho¨nen Olli , Handroos Heikki
Published: June 2008

In the paper a nonlinear load control method is developed and implemented for a permanent magnet linear synchronous motor (PMLSM). The purpose of the controller is to track a flexible load to the desired velocity reference as fast as possible and without awkward oscillation. The control method is based on an adaptive backstepping algorithm whose stability is analyzed by the Lyapunov stability theorem. The states of the system needed in the controller are estimated by using the Kalman filter. The proposed controller is implemented and tested in a linear motor test drive and responses are presented.
Dynamic Analysis of the Nonlinear Behavior of Capacitive MEMS Using the Finite Element Formulation
Authors: Rochus Ve´ronique , Kerschen Gaetan , Golinval Jean-Claude
Published: June 2008

The dynamic response of a mass-spring model of electrostatically actuated MEMS is analyzed when a voltage step is applied. The dynamics of a clamped-clamped beam representing a micro-bridge system are also considered. To model and simulate the strong coupling between the electric and mechanical fields, a general finite element program has been developed based on a new monolithic formulation. The methodology proposed in this program does not require any iterative numerical scheme based on separate electrostatic and mechanical solvers, respectively.
Advanced Model-Based Disturbance Compensation Control Using Proportional-Integral-Observer
Authors: Krajcin Idriz , So¨ffker Dirk
Published: June 2008

This contribution presents a state feedback control and a new disturbance compensation method using the Proportional-Integral-Observer (PI-Observer). For a suitable class of systems the observer estimates the unmeasured states as well as unknown inputs acting on a structure using a small number of measurements. Here, the observer is applied to elastic structures where the PI-Observer can be used for model-based diagnosis and control. An extended disturbance compensation is proposed to improve the dynamical behavior, to decouple the effect of disturbances on defined outputs using the PI-Observer. The observer and the control are applied to an all side clamped elastic plate. The performance of the control is illustrated by simulation results.
V8 Engine Bearing Dynamics: High Perfomance With Minimum Friction
Authors: McLuckie Ian , Barrett Scott
Published: June 2008

This paper concerns the study of the high-speed effects of gas and inertial loading of the bearing system response of a V8 racing crank train system operating at speeds of up to 20,000 rpm. The system has been modelled within the author’s engine design software, which is an object oriented engine design CAE environment. The study is restricted to the bearing responses and resulting system friction whilst operating at speeds of 5,000, 10,000, 15,000 and 20,000 rpm at full load conditions. Two crankshaft configurations have been investigated, the cruciform and the planar crankshaft systems. The bearings have been modelled as Rigid HydroDynamic (RHD) solutions with a Bulirsch-Stoer time integration scheme. The bearing system, frictional response and loading of both engine arrangements have been compared to determine the best configuration from both a loading and overall frictional losses point of view.
Delay Differential Equation Models for Real-Time Dynamic Substructuring
Authors: Wallace Max , Sieber Jan , Neild Simon , Wagg David , Krauskopf Bernd
Published: June 2008

Real-time dynamic substructuring is a testing technique that models an entire system through the combination of an experimental test piece, representing part of the system, with a numerical model of the rest of the system. Delays can have a significant effect on the technique, as signals are passed between the two parts of the system in real-time. The focus of this paper is the influence of the delay on the dynamics of the substructured system. This is addressed using a linear example which may be described by a delay differential equation (DDE) model. This type of analysis allows critical delay values for system stability to be computed, which in turn can be used to help design the substructuring test system. Two methods are presented for the example considered. The first makes use of an analytical approach and the second of a numerical software tool, DDE-BIFTOOL. Normally, in substructuring tests, the actuator’s response time exceeds the critical delay time and the substructured system is unstable. It is demonstrated that the system can be stabilized using an adaptive delay compensation technique based on forward polynomial prediction. Finally we outline how these techniques may be applied to an industrial example of modelling a nonlinear spring.
A Case Study in Backlash Characterization in Mechanical Systems
Authors: Tjahjowidodo T. , Al-Bender F. , Van Brussel H.
Published: June 2008

The Frequency Response Function (FRF) method using an experimental analysis such as free vibration with shock excitation or forced vibration with step or chirp excitation has proven to be a most efficient way to identify the modal parameters of mechanical structures. However, there is a limitation that only linear dynamic systems can be tested through these methods. The problem becomes more complex when nonlinear systems have to be identified. If the nonlinear system is ‘well-behaved’, i.e. if it shows periodic response to a periodic excitation, ‘skeleton’ identification techniques may be used to estimate the modal parameters, in function of the amplitude and frequency of excitation. However, under certain excitation conditions, chaotic behaviour might occur so that the response is aperiodic. In that case, chaos quantification techniques, such as Lyapunov exponent, are proposed in the literature. This paper deals with the application of the aforementioned nonlinear identification techniques to an experimental mechanical system with backlash. It compares and contrasts Hilbert transforms with Wavelet analysis in case of skeleton identification showing their possibilities and limitations. Chaotic response, which appears under certain excitation conditions and could be used as backlash signature, is dealt with both by a simulation study and by experimental signal analysis after application of appropriate filtration techniques.
Assembly Process Selection to Minimize Existing Assembly System Modification Cost During New Product Family Member Design
Authors: Siddique Zahed
Published: June 2008

Proper utilization of available assembly resources can reduce the development time and cost for platforms and new product family members. This paper presents a method to explicitly consider existing assembly plant configuration and resources during selection of assembly process for new product family members. In order to perform the trade-off studies, first constraints on the assembly sequence are identified and used to generate the feasible assembly sequence space, which is combinatorial in nature and is enumerated using recursive functions. The assembly sequence design spaces and representation of effects of constraints on these spaces to explicitly represent feasible regions, and efficiently enumerate designs within this space are investigated. A method that stops recursive growth based on constraints and minimization of assembly plant modification cost is used for efficient search of the feasible assembly sequence space. The assembly sequence modification cost is estimated by dividing assembly plant modification tasks into smaller activities and determining cost associated with each activity. Application of the Assembly Resource Utilization Design Module (ARUDM) to determine assembly sequence while increasing utilization of existing assembly plants is demonstrated using a coffeemaker family.
Experimental Validation of a State-Switched Absorber Used to Control Vibrating Continuous Systems
Authors: Holdhusen Mark , Cunefare Kenneth A.
Published: June 2008

A state-switched absorber (SSA) is a device capable of instantaneously changing its stiffness, thus it can switch between resonance frequencies, increasing its effective bandwidth as compared to classical tuned vibration absorbers for vibration control. Previous numerical work has shown that an optimized SSA outperforms an optimized TVA at controlling vibrations of both a beam and a plate. This paper details the experimental validation of these simulation results. An SSA was realized by employing magneto-rheological elastomers to achieve a stiffness change. The stiffness of these elastomers is a function of the magnetic field put across them. Experiments were conducted on both a cantilever beam and a square plate clamped on all sides. Each system was excited by several two-frequency component excitations. For each forcing combination, several tuning configurations of the SSA were applied and the kinetic energy of the system was found. This observed performance was compared to the performance found through numerical simulations of a system with a similar tuning and excitation configuration. It was found that the observed performance follows closely with results found through numerical simulation.
Nonlinear Dynamics of Pneumatic Tires and Application to Elastic Vehicles
Authors: Bo¨hm Friedrich
Published: June 2008

A vehicle is a light weight elastic, hysteretic damped free body only connected with the assumed intertial system by accelerations and mutual contact forces. Tires produce, if in contact with the ground, accelerations at the axles and all mass elements have to be integrated simultanously to get their pathes, according to Newton’s law. The rotational motion of the body-tire system is very sensitive to disturbances in the accelerations and changes the slip conditions of the tires. Nonlinearity is kinematic, compression stiffness, friction and hysteresis. Slip is simulated using the dislocation way of sensor points on the surface. The slip conditions together with the contact conditions produce the nonlinear tire deformations in every computed time step. Relevant time intervals are to be elucidated from frequency measurements and are to be used for defining splitted masses and for connecting with stiffness parameters from material tests. To the resulting central force system a D’Alembert bending force system can be added as a small disturbance. Explicit time integration by predictor-corrector method of third order, controlling acceleration, is used. The computing procedure is therefore an exact central force system only disturbed by a bending force system in equilibrium. No assumption for small nonlinear terms is necesssary, numerical stability is controlled by Shannon and Gershgorin theorems, Lit [1–11].
Benchmarking of MBS Simulation Software
Authors: Gonza´lez Manuel , Lugri´s Urbano , Gutie´rrez Ruth , Cuadrado Javier
Published: June 2008

Despite the importance given to the computational efficiency of multibody system (MBS) simulation tools, there is a lack of standard benchmarks to measure the performance of these kinds of software applications. Benchmarking is done on an individual basis: different sets of problems are used, and the procedures and conditions considered to measure computational efficiency are also different. In this scenario, it becomes almost impossible to compare the performance of the different available simulation methods in an objective and quantitative way. This works proposes a benchmarking system for MBS simulation tools. The system is made up by two components: (a) a collection of test problems with reference solutions and standardized procedures to measure computational efficiency; and (b) a web-based application to collect, organize and share information about performance of existing simulation methods. The benchmarking system has been applied to evaluate the performance of ADAMS/Solver, a popular MBS simulation tool.
Extended Radial Basis Functions for Metamodeling: A Comparative Study
Authors: Mullur Anoop A. , Messac Achille
Published: June 2008

The process of constructing computationally benign approximations of expensive computer simulation codes, or metamodeling, is a critical component of several large-scale Multidisciplinary Design Optimization approaches. Such applications typically involve complex models, such as finite elements, computational fluid dynamics, or chemical processes. The decision regarding the most appropriate metamodeling approach usually depends on the type of application. However, several newly-proposed kernel-based metamodeling approaches can provide consistently accurate performance for a wide variety of applications. The authors recently proposed one such novel and effective metamodeling approach — the Extended Radial Basis Function approach — and reported encouraging results. To further understand the advantages and limitations of this new approach, we compare its performance to that of the typical radial basis function approach, and another closely related method — kriging. Several test functions with varying problem dimensions and degrees of nonlinearity are used to compare the accuracies of the metamodels using these metamodeling approaches. We consider several performance criteria, such as metamodel accuracy. effect of sampling technique, effect of problem dimension, and computational complexity. The results suggest that the E-RBF approach is a potentially powerful metamodeling approach for MDO-based applications.
Insertion of Planar Areas Into Free-Form Surfaces in Early Product Design
Authors: Cheutet V. , Pernot J. P. , Le´on J. C. , Falcidieno B. , Giannini F.
Published: June 2008

Surfaces, like planes, cylinders or spheres, are basic primitive surfaces not only for mechanical engineering but also for aesthetic design, world of free-form surfaces, where they are essentially used to answer some functional constraints, like assembling and manufacturing ones, or to achieve specific light effects. The early design steps are characterised by the uncertainty in the definition of the precise geometry and most of the time, product constraints are only partially available. Unfortunately, until now, the insertion of primitive surfaces requires precise curve and surface specifications together with trimming operations, thus imposing that the free-form geometry is recreated each time a modification occurs. In this paper we present a method for the insertion of planar surfaces suitable to handle the uncertainty in the first draft of a product. The approach does not provide effective precise primitive surfaces, but it is able to introduce regions resembling such a behaviour in a free-form surface, without requiring trimming operations, so allowing more efficient shape alternative evaluations.
Effect of the Linearization of the Kinematic Equations in Railroad Vehicle System Dynamics
Authors: Shabana Ahmed A. , Tobaa Mahmoud , Marquis Brian , El-Sibaie Magdy
Published: June 2008

The sensitivity of the wheel/rail contact problem to the approximations made in some of the creepage expressions is examined in this investigation. It is known that railroad vehicle models that employ kinematic linearization can predict, particularly at high speeds, significantly different dynamic response as compared to models that are based on fully nonlinear kinematic and dynamic equations. In order to analytically examine this problem and numerically quantify the effect of the approximations used in the linearized railroad vehicle models, the fully nonlinear kinematic and dynamic equations of a wheel set are presented. The linearized kinematic and dynamic equations used in some railroad vehicle models are obtained from the fully nonlinear model in order to shed light on the assumptions and approximations used in the linearized models. The assumptions of small angles that are often made in developing railroad vehicle models and their effect on the angular velocity, angular acceleration, and the inertia forces are investigated. The velocity creepage expressions that result from the use of the assumptions of small angles are obtained and compared with the fully nonlinear expressions. Newton-Euler equations for the wheel set are presented and their dependence on Euler angles and their time derivatives is discussed. The effect of the linearization assumptions on the form of Newton-Euler equations is examined. A suspended wheel set model is used as an example to obtain the numerical results required to quantify the effect of the linearization. The results obtained in this investigation show that linearization of the creepages can lead to significant errors in the values predicted for the longitudinal and tangential forces as well as the spin moment. There are also significant differences between the two models in the prediction of the lateral and vertical forces used to evaluate the L/V ratios as demonstrated by the results presented in this investigation.
A Search Algorithm of Interface Structure to Achieve Required Product Behavior
Authors: Koga Tsuyoshi , Aoyama Kazuhiro
Published: June 2008

The design of interactions of product components, i.e., an interface structure, is a very difficult design problem, because the whole product behavior is determined by the interface structure. This paper proposes a new algorithm that can be used to derive the interface structure automatically to achieve the required product behaviors. Generally, two or more different design proposals can achieve the same required product behavior. Therefore, the designer must select the better design proposal based on consideration of both cost and mechanical constraints. To support the evaluation, decision, and selection by the designer, an evaluation method for product behavior by comparison of the required product behavior is proposed. We call this methodology the design system of Product Behavior by automatic calculation of the Interface Structure (PBIS). Here, we demonstrated the effectiveness of the PBIS algorithm in an implemented prototype system. PBIS enables the designer to determine the interface structure interactively based on a list of proposed interface structures that can realize the required product behavior. The methodology addresses: (1) how the interface structure problem should be formulated; (2) how the algorithm for automatic proposition of the interface structure achieves the required product behaviors; and (3) the evaluation method of the interface structure by comparison between the required product behavior and achieved product behavior.
A Software Application to Assist Machine Tools Configuration
Authors: Flores Miguel A´. , Borja Vicente , Ayala A´lvaro , Lo´pez Marcelo
Published: June 2008

The selection of manufacturing resources affects the cost, time, and quality of products. Manufacturing resources must be selected to fulfill product design specifications and production requirements. One particular case of determining resources is the configuration of machine tools, as it includes the selection of the required machine tools and the corresponding cutters, fixtures and operation conditions. This paper describes a machine tools configuration process and a software application based on information models to assist it. The process has been devised to concurrently select resources and determine operation conditions, emphasizing the close relationship that exists between them and to guarantee their compatibility. The information models represent product and manufacturing data, and capture suppliers catalogues information. The software applications employ neural networks to select manufacturing process and resources, and genetic algorithms to determine operation conditions to obtain a compromise between cost, time and quality. The utility of the approach is explored through a case study.
Function Based Risk Assessment: Mapping Function to Likelihood
Authors: Grantham Lough Katie , Stone Robert , Tumer Irem Y.
Published: June 2008

Risk assessments are necessary to anticipate and prevent accidents from occurring or repeating. This paper focuses specifically on the relationship between function and risk by presenting a mathematical mapping from product function to risk likelihood. This type of mapping will aid designers by removing the subjectivity of the likelihood value from a risk element, provide three key risk element properties (design parameter, failure mode, and likelihood) for numerous risk elements with one simple mathematical calculation, and provide a means for inexperienced designers to effectively address risk in the conceptual design phase. In addition, the level of detail a functional model should be written in to produce adequate likelihood risk assessments is examined. Three case studies are used to validate the proposed mapping: A spacecraft orientation subsystem, a subsystem to guide science instruments on an extraterrestrial, and subsystems from a Bell 206 rotorcraft. The work described in this paper continues is part of ongoing research relating function to failure.
Collaborative Optimization Strategy for Multi-Objective Design
Authors: De´pince´ Philippe , Rabeau Se´bastien , Bennis Fouad
Published: June 2008

The increasing economic competition of all industrial markets and growing complexity of engineering problems lead to a progressive specialization and distribution of expertise, tools and works. On the other hand, engineering products becomes more and more complex and the designer has to face with an increase design variables and design objectives. Besides multi-objective optimization (MOO) and multi-disciplinary design optimization (MDO) are more commonly used as methods to provide optimal solutions for complex design problems. The paper describes an innovative mixing between genetic algorithms (MOGA) and collaborative optimization (CO) as a tool to: 1) increase the convergence rate when a design problem can be broken up regarding design variables, and 2) provide an optimal set of design variables in case of multi-level design problem. This method gives multidisciplinary optimization the advantages AG has brought to multi-objective optimization. The method, tested on test functions, assures high optimization results containing CPU times.