bluuebunny/crossref_metadata_2025 huggingface dataset:
Rotor Drop Transient Analysis of AMB Machinery
Authors: Kirk R. G. , Gunter E. J. , Chen W. J.
Published: June 2008

A major limitation of AMB supported machinery is their dependence on auxiliary or backup bearings in the event that the magnetic bearings lose power due to control system failure. These backup bearings should be designed to withstand the severe loads encountered after the AMB failure when the rotor drops onto them. This has prompted the development of general purpose finite element based, non-linear transient analysis programs capable of evaluating shock loading, blade loss and rotor drop phenomena experienced in rotors supported by AMBs. Previous testing and results have been made for a single AMB drop or both AMBs of a two bearing rotor. The current interest also includes the multiple AMB supported machinery systems, i.e., systems with more than two AMB or auxiliary bearings. This paper reviews the method of rotor drop analysis for AMB bearing systems. A commercially available program, DyRoBeS, is then applied to four different rotor designs to evaluate their rotor drop transient response. The total power loss rotor drop results of four different rotor systems will be discussed for assumed backup bearing conditions.
Study of a Hybrid Vibration Isolator and Its Properties
Authors: Zhu Shi-Jian , Wu Xian-Jun
Published: June 2008

In order to isolate the structural vibration in high frequency range effectively, low damping ratio of the isolator is preferred in the high frequency range. While in order to constrain the peak response value near the natural frequency, high damping ratio is preferred. Damping ratio of a passive isolation system is constant with respect to frequency. It cannot fulfill such a conflict request. A novel hybrid isolator, which consists of a passive one and a force actuator, was brought out in this paper to achieve a varying damping ratio with respect to frequency. The force actuator detects the deformation of the isolator and generates actuating force according to a designed transfer function. The transfer function was designed to have the property of increasing the damping near the natural frequency of the suspension system and decreasing the damping ratio in the high frequency range. Two application examples were given and good effect was found.
Fast Simulation of Nonlinear Compliant Mechanisms Using Convective Rate Formulation
Authors: Franitza Daniel , Lichtneckert Timo
Published: June 2008

The current paper addresses modelling and simulation of spatial compliant mechanisms, which links are of one dimensional structure. Applications of compliant mechanisms in macroscopic devices (i.e. clutches, switches) offer the advantages of cost reduction due to a lower number of parts or reduced assembly time and the avoidance of friction and wear. In microscopic devices compliant mechanisms usually apply because classical joints cannot be scaled down to the desired measurements. Usually these structures can be described with respect to their kinematic and kinetic variables for beam elements. Here the basic ideas for the calculation of compliant mechanisms at finite deformations from the viewpoint of continuum mechanics and numerics are applied. A common approach to model and simulate these structures is the use of beam elements with shape functions. Usually problems occur regarding accuracy or convergence if large deformations have to be faced. Here the beam structure is described with respect to the rates of its kinematic and kinetic variables. Using a finite element approach based on transfer matrices leads to a linear Boundary Value Problem embedded into a nonlinear Initial Value Problem. The result of this method is a fast analysis program (KOBA3D), whose abilities are presented in two examples and which results are compared to reference calculations in ABAQUS.
Kinematic Analysis of a New 3-DOF Translational Parallel Manipulator
Authors: Li Yangmin , Xu Qingsong
Published: June 2008

A novel three-degrees-of-freedom (3-DOF) translational parallel manipulator (TPM) with orthogonally arranged fixed actuators is proposed in this paper. The mobility of the manipulator is analyzed via screw theory. The inverse kinematics, forward kinematics, and velocity analyses are performed and the singularities and isotropic configurations are investigated in details afterwards. Under different cases of physical constraints imposed by mechanical joints, the reachable workspace of the manipulator is geometrically generated and compared. Especially, it is illustrated that the manipulator in principle possesses a fairly regular like workspace with a maximum cuboid defined as the usable workspace inscribed and one isotropic configuration involved. Furthermore, the singularity within the usable workspace is verified, and simulation results show that there exist no any singular configurations within the specified workspace. Therefore, the presented new manipulator has a great potential for high precision industrial applications such as assembly, machining, etc.
Smart Asset Maintenance System for Machine Fault Diagnosis: Its Effectiveness, Methodology, and Applications
Authors: Leung Jacko T. , Tse Peter W.
Published: June 2008

Maintenance is essential in all kinds of machines. In past, the machine operators would recognize the machine condition by touching the machine or hearing the machine operating sound. However, this is too subjective and not effective for inexperienced operators. In fact, most modern machineries are so complex that many components may run together, making the operator impossible to distinguish the difference between a normal and anomalous machine. Although more scientific fault diagnostic systems are available, they are expensive and difficult to use without comprehensive learning. Therefore, there is a need from industry to have an economy and efficient machine fault diagnostic system. The occurrence of fault must be identified as early as possible to avoid fatal breakdown of machines. The aim of developing the Smart Asset Maintenance System (SAMS) is to provide a portable and comprehensive but low-cost and simple-to-use solution for the industry to perform equipment maintenance effectively.
A Closed-Form Optimal Kinematic Design of the PRRRP Parallel Manipulator
Authors: Liu Xin-Jun , Wang Jinsong
Published: June 2008

This paper addresses the optimal kinematic design of the PRRRP parallel manipulator that is actuated horizontally by linear actuators. Kinematically, the symmetrical PRRRP parallel manipulator has only one geometric parameter, i.e., the link length of each of the two legs. Here, we propose a design approach utilizing the performance chart and local performance specification. The key problem in the design of the manipulator is the determination of not the link length but the workspace that the manipulator can reach satisfying the design specification. Such a kind of workspace when the link length is unit is defined as the basic good-conditioning workspace (GCW). For the manipulator studied here, the link length is actually the ratio of the desired task workspace to the basic GCW. This paper gives an effective method to obtain the basic GCW with respect to indices in closed form. One of the advantages of the method is that the basic GCW is achieved by taking into account both the global and local indices.
Analytical Investigation of the Dynamics of a Nonlinear Structure With Two Degree of Freedom
Authors: Pascal Madeleine
Published: June 2008

A two degree of freedom oscillator with a colliding component is considered. The aim of the study is to investigate the dynamic behavior of the system when the stiffness obstacle changes from a finite value to an infinite value. Several cases are considered. First, in the case of rigid impact and without external excitation, a family of periodic solutions are found in analytical form. In case of soft impact, with a finite time duration of the shock, and no external excitation, the existence of periodic solutions, with an arbitrary value of the period, is proved. Periodic motions are also obtained when the system is submitted to harmonic excitation, in both cases of rigid or soft impact. The stability of these periodic motions is investigated for these four cases.
Power Transmission System Modeling
Authors: Ebrahimi M. , Whalley R.
Published: June 2008

The modeling of mechanical power transmission systems comprising rotors, shafts and bearing assemblies will be considered. Spatially dispersed elements, with significant distributed inertia and stiffness characteristics, will be included in the system descriptions. Relatively concentrated units will be modeled using conventional lumped parameter techniques. Compact, accurate analytical models in impedance and admittance form will be derived enabling the investigation of the combined distributed-lumped system’s, torsional response dynamics. The performance of the system under open and closed -loop conditions will be illustrated via computer studies. Typical mechanical drive application will be presented.
A Reduced Order System ID Approach to the Modeling of Nonlinear Structural Behavior in Aeroelasticity
Authors: Attar Peter J. , Dowell Earl H.
Published: June 2008

A method is proposed for identifying a set of reduced order, nonlinear equations which describe the structural behavior of aeroelastic configurations. The strain energy of the system is written as a (polynomial) function of the structures’ modal amplitudes. The unknown coefficients of these polynomials are then computed using the strain energy data calculated from a steady state, high-order, nonlinear finite element model. The resulting strain energy expression can then be be used to develop the modal equations of motion. From these equations zero and nonzero angle of attack flutter and LCO data are computed for a 45 degree delta wing aeroelastic model. The results computed using the reduced order model compare well with those from a high fidelity aeroelastic model and to experiment. A two to three order of magnitude reduction in the number of structural equations and a two order of magnitude reduction in total computational time is accomplished using the current reduced order method.
Study on Optimization Design of Hybrid Vibration Isolation System on Flexible Foundation
Authors: Mao Wei-Min , Zhu Shi-Jian , Jiang Hui-Ming
Published: June 2008

This article analyzes the process to design hybrid vibration isolation system on flexible foundation. The dynamic model of a hybrid vibration isolation system on flexible foundation is build and the character of power flow transmission is analyzed by sub-system structure impedance synthesis technique and four poles parameter method. The global sensitivity analysis with the Sobol’ method is used to study the global sensitivity behavior of the hybrid vibration isolation system. The multi-objective optimization design method of hybrid vibration isolation system is studied and the mathematic optimization model has been built. Gene algorithm has been used to solve the global optimization problem, and the numerical simulation is carried out.
Self-Excited Oscillation of a Taut String in a Wire-Plate Electrode System With a Corona Discharge
Authors: Itoh Yoshiaki , Yoshizawa Masatsugu , Ikejiri Noritaka , Kumashiro Takashi
Published: June 2008

In this paper, the existence of self-excited oscillation of a taut string is observed when the string is stretched in a wire-plate electrode system with a corona discharge in order to give some useful information on final goal of our research. The goal is to explain the outbreak mechanism of self-excited oscillation of the wire electrode in the wire-plate electrode system. Some experiments are made under the condition that the wire oscillation is not excited. This means that an electrostatic field is constant with respect to time, and only a fluid field is unsteady even though the string oscillation is excited. As a result, the horizontal component of the string oscillation is self-excited with the fundamental natural frequency. In particular, the similarity between the string oscillation and the wire oscillation is confirmed. Moreover, relationship between the fluid force and the string oscillation is examined experimentally. It is confirmed that the fluid force is main reason for the outbreak mechanism of the string oscillation. Furthermore, the outbreak mechanism is discussed theoretically under some assumptions, and a guideline for our future theoretical work is also indicated.
A VR-Based Data Retrieval System
Authors: Yu Chunsheng , Peng Qingjin , Wu Lushen
Published: June 2008

Concurrent Engineering (CE) considers a product design and manufacturing simultaneously. The CE research has led to the product information integration. However, the current CE research focuses on smooth of the product information flow rather than a user-friendly searching process for users to obtain product information quickly. A new data retrieval system for product design and manufacturing is proposed in this paper. The system not only provides an integrated product database, but also uses Virtual Reality (VR) and Web technologies for easing navigation in product data and for accelerating access to useful information. The effective collaboration in a product design and manufacturing can be achieved through the proposed information searching method. Examples are presented in the discussion.
Quality Control of Micro-Drilled Hole Wall of PWBs Using Data-Mining
Authors: Aoyama Eiichi , Hirogaki Toshiki , Ogawa Keiji , Otsuka Tsuyoshi , Yamauchi Katsutoshi
Published: June 2008

In the manufacturing of printed wiring boards (PWBs), various methods have been developed in order to improve the circuit packaging density. Micro-drills are generally used to make smaller diameter through-holes in PWBs, which are desired for the miniaturization of equipment. However, a problem has emerged in that copper plating degraded by hole drilling can reduce the reliability of the electrical connection between layers. The surface roughness of drilled hole wall is one of the important factors affecting the plating quality. The purpose of the present report is to apply data-mining to the surface roughness data of drilled through-hole walls, and to elucidate the factors required to control the drilled hole quality. The following conclusions were obtained. (1) The data-mining aided by a computer was found to be effective to control the drilled hole wall quality in the PWBs manufacturing. (2) It was clear that the surface roughness of drilled hole walls depended on three factors: the drill temperature, cutting distance, and the width of the fiber bundle of weft yarn.
Methodology to Reach Optimal Design of CHP Plants
Authors: Gonzalez-Chapa Manuel-Angel , Vega-Galaz Jose-Ramon
Published: June 2008

A methodology to reach the best CHP plant design is proposed. The standard method to choose the best fit in the process design of a CHP plant is improved considering off-design simulation of the pre-selected schemes. The off-design simulation deals specifically with economic dispatch optimization applied on each pre-selected plant to calculate the operation performance under well-known heat and power loads. The economic dispatch include fuel, uniform series payments related with investment and operation & maintenance costs and evaluates the variable behavior for power and heat along time with a scenario that takes into account transactions with the utility grid as well as auxiliary or back up boilers. It is shown the different result reached in each approach and the new point of view gotten with the use of the methodology proposed.
Nonlinear Statical and Dynamical Models of Fractional Derivative Viscoelastic Body
Authors: Nasuno H. , Shimizu N.
Published: June 2008

The authors have been conducting experiments on the investigation of nonlinear quasi-statical and dynamical behaviors of a viscoelastic body described by the fractional derivative law. Pre-stress due to pre-displacement induces high damping performance during sinusoidal excitation. To understand this behavior, nonlinear statical and dynamical models are investigated by theoretical consideration. The authors establish and propose appropriate models to describe the nonlinear behavior of the fractional derivative viscoelastic body. The nonlinearity of the viscoelastic coefficient for quasi-statical compressive displacement may be described by the power function with respect to pre-displacement and the nonlinearity of the viscoelastic coefficient for sinusoidal excitation may be described by the exponential function with respect to pre-displacement. Some discussions on the values of the viscoelastic coefficients.
A Method for Integrating Form Errors Into Geometric Tolerance Analysis
Authors: Pierce Robert Scott , Rosen David
Published: June 2008

In this research we describe a computer-aided approach to geometric tolerance analysis for assemblies and mechanisms. This new tolerance analysis method is based on the “generate-and-test” approach. A series of as-manufactured component models are generated within a NURBS-based solid modeling environment. These models reflect errors in component geometry that are characteristic of the manufacturing processes used to produce the components. The effects of different manufacturing process errors on product function is tested by simulating the assembly of these imperfect-form component models and measuring geometric attributes of the assembly that correspond to product functionality. A tolerance analysis model is constructed by generating-and-testing a sequence of component variants that represent a range of manufacturing process capabilities. The generate-and-test approach to tolerance analysis is demonstrated using a case study that is based on a high-speed stapling mechanism. As-manufactured models that correspond to two different levels of manufacturing precision are generated and assembly between groups of components with different precision levels is simulated. Misalignment angles that correspond to functionality of the stapling mechanism are measured at the end of each simulation. The results of these simulations are used to build a tolerance analysis model and to select a set of geometric form and orientation tolerances for the mechanism components. It is found that this generate-and-test approach yields insight into the interactions between individual surface tolerances that would not be gained using more traditional tolerance analysis methods.
Ziegler-Nichols Type Tuning Rules for Fractional PID Controllers
Authors: Vale´rio Duarte , Sa´ da Costa Jose´
Published: June 2008

This paper presents two sets of tuning rules for fractional PIDs that rely solely on the same plant time-response data used by the first Ziegler-Nichols tuning rule for (usual, integer) PIDs. Thus no model for the plant to control is needed; only an S-shaped step response is. These rules are quadratic and their results compare well with those obtained with rule-tuned integer PIDs.
Dynamic-Signal Characterization of Rotary Machinery Using Improved Gabor Order Tracking Technique
Authors: Pan Min-Chun , Liao Shu-Wei
Published: June 2008

The study proposes an improved Gabor order tracking (GOT) technique to cope with crossing orders that cannot be effectively separated by using the original GOT scheme. The improvement aids both the reconstruction and interpretation of two crossing orders such as a transmission-element- related order component and a structural resonance. The dual function of the Gabor elementary function can affect the precision of tracked order components. Its influence on the computed Gabor expansion coefficients is investigated in the study. For applying the improved GOT in practical works, the separation and extraction of close-order components of vibration signals measured from a transmission-element test bench is illustrated by using both the GOT and Vold-Kalman filtering OT schemes. Additionally, the ranking of noise components from a riding electric scooter is demonstrated.
Order Tracking Techniques in Diagnostic Tasks
Authors: Pan Min-Chun
Published: June 2008

Order tracking techniques have been applied in processing dynamic signals measured from rotary machines for decades. The developed order tracking techniques can be classified into waveform reconstruction and non-reconstruction approaches. The waveform-reconstruction schemes such as the Gabor and the Vold-Kalman filtering order tracking techniques can extract specific order and/or spectral components in addition to characterizing the processed signal in an rpm-frequency plane. The paper objectively compares the characteristics of the improved Gabor order tracking and angular-displacement Vold-Kalman Filtering order tracking schemes. Two diagnostic tasks including ECG signal reconstruction to enhance tiny information, and the characterization of crossing-order noise measured from a riding electric scooter, are accomplished as examples of application.
3D CAD Model Similarity Assessment and Retrieval Using DBS
Authors: Gao Wei , Gao Shuming , Liu Yusheng
Published: June 2008

Similarity assessment and retrieval of 3D CAD models play a key role in achieving reuse of huge amount of 3D CAD models. In this paper, a new approach to similarity assessment and retrieval of 3D CAD models based on dilation based skeleton (DBS) is presented. First the DBS of a 3D CAD model is introduced; Then the detailed algorithms of generating and refining the DBS of a 3D CAD model are described; Furthermore the method of performing similarity assessment and retrieval of 3D CAD models based on the matching of the DBS graphs derived from the DBS representations and containing both primary topological and geometric information of the models is presented; Finally some preliminary test results are given.
A New O(n) Method for Inverting the Mass Matrix for Serial Chains Composed of Rigid Bodies
Authors: Wang Yunfeng , Chirikjian Gregory S.
Published: June 2008

Over the past several decades a number of O(n) methods for forward and inverse dynamics computations have been developed in the multibody dynamics and robotics literature. In this paper, a method developed in 1973 by Fixman for O(n) computation of the mass-matrix determinant for a polymer chain consisting of point masses is adapted and modified. In other recent papers, we and our collaborators recently extended this method in order for Fixman’s results to be applicable to robotic manipulator models with lumped masses. In the present paper we extend these ideas further to the case of serial chains composed of rigid-bodies. This requires the use of relatively deep mathematics associated with the rotation group, SO(3), and the special Euclidean group, SE(3), and how to differentiate functions of group-valued argument.
Non-Linear Dynamic Analysis of a Cable-Stayed Beam
Authors: Mazzilli Carlos E. N. , Villarroel Rojas Franz Rena´n
Published: June 2008

The dynamic behaviour of a simple clamped beam suspended at the other end by an inclined cable stay is surveyed in this paper. The sag due to the cable weight, as well as the non-linear coupling between the cable and the beam motions are taken into account. The formulation for in-plane vibration follows closely that of Gattulli et al. [1] and confirms their findings for the overall features of the equations of motion and the system modal properties. A reduced non-linear mathematical model, with two degrees of freedom, is also developed, following again the steps of Gattulli and co-authors [2,3]. Hamilton’s Principle is evoked to allow for the projection of the displacement field of both the beam and the cable onto the space defined by the first two modes, namely a “global” mode (beam and cable) and a “local” mode (cable). The method of multiple scales is then applied to the analysis of the reduced equations of motion, when the system is subjected to the action of a harmonic loading. The steady-state solutions are characterised in the case of internal resonance between the local and the global modes, plus external resonance with respect to either one of the modes considered. A numerical application is presented, for which multiple-scale results are compared with those of numerical integration. A reasonable qualitative and quantitative agreement is seen to happen particularly in the case of external resonance with the higher mode. Discrepancies should obviously be expected due to strong non-linearities present in the reduced equations of motion. That is specially the case for external resonance with the lower mode.
Design and Experimental Research of Magneto-Rheological Fluid Fan Clutch
Authors: Shen Yuliang , Yang Shaopu , Pan Cunzhi
Published: June 2008

The fundamental principle of MR fluid fan clutch in transmitting torque is analyzed, in the meantime, a shear model of MR clutch is proposed; MR fluid fan clutch having simple, novel structure is designed and made; At the same time, on the basis of experiments, the characteristic of velocity regulating of the clutch is studied in detail. The experimental results indicate that, compared with the shearing rate, the change of magnetic fields has a tremendous influence on the speed regulating characteristic of a fan clutch, and output torque of fan clutch can satisfy demand of engine cooling fan.
An Experimental Investigation of the Natural Frequencies of the Tracheobronchial Network
Authors: Au P. M. , Al-Jumaily A. M.
Published: June 2008

Determining the natural frequencies of cylindrical non uniform tissues such as the tracheobronchial branched network is a task of multiple difficulties. Two classical experimental procedures, based on mechanical and acoustical excitations, are adopted to determine these frequencies and the results are compared with some numerical values. Although in-vitro test samples of pigs’ tissues are used for the measurements, the results are well indicative of some of the in-vivo dynamic behavior of the respiratory system, which could be correlated to diagnosis and control of lung disorders.
Seismic Response Analysis System by Means of Multibody Dynamics Approach: Modeling and Analysis of Geometric Time Varying Structure Systems
Authors: Takahashi Yoshitaka , Shimizu Nobuyuki
Published: June 2008

In Japan, the seismic design methods for structures are developed in the civil and architectural fields. And these seismic design technologies have also been brought to mechanical structures such as piping facilities and boiler structures, etc.. But, for the geometric time varying structure of which geometric configuration is dependent on time such as cranes, the kinetic and the dynamic characteristics of such structures are not fully considered in the seismic response analyses. In this paper, we try the modeling of the geometric time varying structure systems by means of the method of multibody dynamics. And we examine the effect of the geometric time varying system on the seismic response. The beam elements formulated by the absolute nodal coordinate are used to model the structure that has large displacement motion of the base of the structure. The crane structure for the building construction is modeled in the numerical example. The seismic responses of the moving boom part of the crane model are simulated. New phenomenon has been explored.
Analysis for Compression Strength of Elbow Rubber Hose Reinforced by Fibers
Authors: Shuai Chang-Geng , He Lin , Lv Zhi-Qiang
Published: June 2008

The stress of curved rubber hose with inner pressure is analyzed. On the base of the spiraled geometrical configuration of fiber around the curved rubber hose, the formulation of its neutral angle and compression strength is derived. The theoretical analysis and experimental results indicate that the axial stress of curved rubber hose with inner pressure is the same as that of straight rubber hose, and the hoop stress of curved rubber hose with inner pressure reaches the maximum value on the inside of its camber line and the minimum value on its outside respectively. The compression strength of curved rubber hose is not only dependent on the strength, layer and spiraled density of reinforced materials, but also on its geometrical configuration.
Stiffness Control of Multi-DOF Joint by Passive/Active Parallel Actuation
Authors: Koganezawa Koichi , Inomata Hiroshi , Nakazawa Toshiki
Published: June 2008

This paper deals with mechanical stiffness control of multi-DOF joint. It fundamentally mimics skeleto-muscular system of human articulation, in which at least two muscles cooperatively handle one DOF under their antagonistic action. In the first part of the paper one describes a novel actuator called ANLES (Actuator with Non-Linear Elastic System) that mimics a skeletal muscle in the sense of having a non-linear elasticity. Next one introduces a basic formula for controlling stiffness of the joint as well as its angles using multiple ANLESes. It follows the evaluation of the proposed formula by the simulation analysis. Three DOF joint manipulated by six or eight tendons that are individually controlled by the ANLES is evaluated with respect to the stiffness control. Based on the results of the simulation a new mechanism for the wrist joint having three DOF is proposed in the practical feasibility, in which only four ANLESes are used to control the stiffness of the wrist.
Dynamics of Multibody Systems With Spherical Clearance Joints
Authors: Flores P. , Ambro´sio J. , Claro J. C. P. , Lankarani H. M.
Published: June 2008

This work deals with a methodology to assess the influence of the spherical clearance joints in spatial multibody systems. The methodology is based on the Cartesian coordinates, being the dynamics of the joint elements modeled as impacting bodies and controlled by contact forces. The impacts and contacts are described by a continuous contact force model that accounts for geometric and mechanical characteristics of the contacting surfaces. The contact force is evaluated as function of the elastic pseudo-penetration between the impacting bodies, coupled with a nonlinear viscous-elastic factor representing the energy dissipation during the impact process. A spatial four bar mechanism is used as an illustrative example and some numerical results are presented, being the efficiency of the developed methodology discussed in the process of their presentation. The results obtained show that the inclusion of clearance joints in the modelization of spatial multibody systems significantly influences the prediction of components’ position and drastically increases the peaks in acceleration and reaction moments at the joints. Moreover, the system’s response clearly tends to be nonperiodic when a clearance joint is included in the simulation.
Visualizing the Time Motion of Planar Mechanisms With Volume Methods
Authors: Bailley Mike
Published: June 2008

Two dimensional, or planar, mechanism design is a mainstay of Mechanical Engineering modeling and analysis. An important part of the design process is the visualizing of the motion of the mechanism. This paper describes a novel approach to visualizing the time motion of a planar mechanism — turning the time dimension into a spatial dimension. All three dimensions (x,y,time) are then treated as a 3D volume. From there, we use interactive volume visualization techniques, including slicing and thresholding. As is seen, this method is able to produce new insights into planar mechanism motion, particularly when more than one mechanism is working cooperatively.
Modeling and Imaging Mechanical Chaos
Authors: Bailley Mike
Published: June 2008

The word “chaotic system” [Peitgen92] describes a system whose outputs are very sensitive to its initial conditions. Because of their inherent complex nature, chaotic systems are difficult to visualize and understand. This paper describes the visualization of a mechanical chaotic system — a magnetic pendulum. The program uses dynamics modeling and imaging, so that a user can experiment with different configurations and then visualize how that configuration responds to all input conditions. The result shows interesting patterns and insights into the mechanical system itself. This same technique would be applicable to visualizing many other chaotic systems.
A Comparison on the Performance of Heuristic Methods of Search for Parameter Characterization of the Bouc/Wen Model of Mechanical Hysteresis
Authors: Hornig Klaus H. , Flowers George T.
Published: June 2008

The Bouc/Wen model of mechanical hysteresis may be stated as a system of coupled parametric nonlinear differential equations of third order. This model is based on the equation of motion with damping for a single degree-of-freedom (DOF) system, which is able to reproduce the dynamics of a wide variety of hysteresis shapes, depending on the values of the seven parameters present in the equations. The characterization of the parameters that describe the specific shapes of hysteresis loops is not an easy task, due to the complexity of the model and the great amount of local minima in the search space. Accordingly, heuristic methods of search (optimization) must be carried out in order to curve-fit the model to the trial data sets, in order to extract damping information. Previous works on this topic deal with optimization using Genetic Algorithms (GA). This paper presents a new approach, using Particle Swarm Optimization (PSO). The performances of both methods are then compared when used for artificial and experimental hysteresis loops obtained for sandwich composite materials under test. Some damping measurement techniques often used by researchers are also explained.
Evaluation of Modular Design Concepts of Complex Mechatronic Systems
Authors: Hehenberger Peter , Zeman Klaus
Published: June 2008

Synergies and integration in design set a mechatronic system apart from a traditional, multi-disciplinary system. This paper proposes a method for the modularization and evaluation of different mechatronic design concepts in the early stages of product development processes. In order to consider the specific aspects of complex systems, a design metric is presented, which assists the design engineer in finding the best solution concept. For the description and evaluation of a complex mechatronic system, it is essential to decompose the total system into a hierarchical structure of mechatronic sub-modules. The number of levels in the decomposition, as well as the number of mechatronic modules involved, is indicative of the complexity of the design task.
Detecting Suspicious Behavior From Only Positional Data With Distributed Sensor Networks
Authors: Rowe Neil C.
Published: June 2008

Wireless sensor networks are increasingly popular, and are being used to measure simple properties of their environment. In many applications such as surveillance, we would like them to distinguish “suspicious” behavior automatically. We distinguish here between suspicious and anomalous behavior, and develop a mathematical model which we illustrate on some sample data. We show the model predicts six classic deception strategies. We conclude with analysis of more sophisticated deceptions that exploit system responses to simpler deceptions.
Modeling of Non-Linear Relations Among Different Design Evaluation Measures for Multi-Objective Design Optimization
Authors: Yang H. , Xue D. , Tu Y. L.
Published: June 2008

This research introduces a new approach to model the non-linear relations among different design evaluation measures and to achieve the optimal design considering these different design evaluation measures through multi-objective optimization. In this approach, different design evaluation measures are mapped to comparable design evaluation indices. The non-linear relation between a design evaluation measure and its design evaluation index is identified based on the least-square curve-fitting method. The weighting factors for different design evaluation indices, representing the importance measures of these indices in the multi-objective design optimization, are achieved using the pair-wise comparison method. A case study example of automobile caliper disc brake design considering 4 different design evaluation measures is given to illustrate the effectiveness of the introduced approach.
On the Development of a Fast Fourier Transform (FFT)-Accelerated Stokes Flow Solver for Drag Computation on MEMS Devices
Authors: De Suvranu
Published: June 2008

In this paper we report the development of a technique of computing the fluid drag forces on single and multiple micro-machined devices using a Fast Fourier Transform (FFT)-accelerated solver for the integral form of the incompressible Stokes flow equations. The boundary element formulation necessitates the discretization of the surface of the device using a large number of “panels” whose interactions are coupled by multidimensional Stokes kernels. The resulting “n-body” problem generates dense matrices that can be solved in O(n log n) complexity using a pre-corrected FFT approach, where ‘n’ is the number of panels used in discretizing the surface of the device. However, for single and multi-body problems, steps must be taken to eliminate the null space of the Stokes kernel to obtain a unique solution. Also discussed are techniques of improving the numerical efficiency of the multiresolution computational scheme.
Automotive Product Design and Development: The Current State and Looking Into the Future
Authors: Verma Dhiren
Published: June 2008

This paper shall present the details of recently conducted studies that examine the criteria for success and the future of product development in the automotive industry. A majority of the forecasts predict increasing globalization, cost containment, dependence on suppliers and increase in electronics content. Correspondingly, OEM’s and suppliers are adopting and implementing CAD and PLM strategies that shall be explored together with the ideal PLM strategy for OEM’s and suppliers.
Principal Parametric Resonance of Axially Accelerating Viscoelastic Strings
Authors: Chen Li-Qun
Published: June 2008

The steady-state transverse responses and the stability of an axially accelerating viscoelastic string are investigated. The governing equation is derived from the Eulerian equation of motion of a continuum, which leads to the Mote model for transverse motion. The Kirchhoff model is derived from the Mote model by replacing the tension with the averaged tension over the string. The method of multiple scales is applied to the two models in the case of principal parametric resonance. Closed-form expressions of the amplitudes and the existence conditions of steady-state periodical responses are presented. The Lyapunov linearized stability theory is employed to demonstrate that the first (second) nontrivial steady-state response is always stable (unstable). Numerical calculations show that the two models are qualitatively the same, but quantitatively different. Numerical results are also presented to highlight the effects of the mean axial speed, the axial speed fluctuation amplitude, and the viscoelastic parameters.
Reduction of Vibration for an Axially Moving String With a Tensioner
Authors: Chen Li-Qun , Zhang Wei
Published: June 2008

This paper deals with reducing transverse vibration for an axially moving string by a damped tensioner. The governing equation and the boundary conditions are derived for the system. Based on the analysis of the reflection and transmission of waves propagating along the string, the maximal energy dissipation is realized by determining the optimal damping. To simulate numerically the effect of vibration reduction, the Crank-Nicolson scheme is applied to discretize the governing equation of the string. The numerical results demonstrate the optimality of the determined damping in suppressing the transverse vibration.
Fractional Derivative Consideration on Nonlinear Viscoelastic Dynamical Behavior Under Statical Pre-Displacement
Authors: Fukunaga Masataka , Shimizu Nobuyuki , Nasuno Hiroshi
Published: June 2008

Nonlinear fractional calculus model for the viscoelastic material is examined for oscillation around the off-equilibrium point. The model equation consists of two terms of different order fractional derivatives. The lower order derivative characterizes the slow process, and the higher order derivative characterizes the process of rapid oscillation. The measured difference in the order of the fractional derivative of the material, that the order is higher when the material is rapidly oscillated than when it is slowly compressed, is partly attributed to the difference in the frequency dependence between the two fractional derivatives. However, it is found that there could be possibility for the variable coefficients of the two terms with the rate of change of displacement.
Automatic Decomposition and Refinement of Oversized Components for Rapid Prototyping
Authors: Medellin H. , Lim T. , Corney J. , Ritchie J. M. , Davies J. B. C.
Published: June 2008

The objective of the work presented in this paper is to enable production of large, complex components on rapid prototyping (RP) machines whose build volume is less than the size of the desired component. Such oversized parts can be produced as fabrications if a suitable subdivision can be generated. The methodology presented here creates a decomposition designed for both Rapid Prototyping (DFRP) and assembly (DFA). Any component can be subdivided by an array of orthogonal planes but the shapes resulting from such a brute force approach could have geometries that are difficult to produce accurately on many rapid prototyping systems. Typically, complications will arise when features have insufficient strength to withstand finishing processes or have a cross-section prone to distortion (e.g. warping) during the build process (e.g. thin sections and cusps). Consequently, the method proposed for partitioning considers potential manufacturing problems and modifies the boundaries of individual components where necessary. As part of the decomposition process, the system also generates complimentary male/female (i.e. matching protrusion/depression) assembly features at the interface between the component parts in order to improve the integrity of the final component.
Identification of Nonlinear and Chaotic Behavior in Model-Scale Liquefied Natural Gas (LNG) Carrier Experimental Data
Authors: McCue Leigh S. , Troesch Armin W.
Published: June 2008

This paper presents the results of an experimental study simulating the behavior of LNG carriers with partially filled tanks exposed to beam seas. Details of the experimental model and method of data collection are presented. Additionally, surrogate data testing is employed to demonstrate nonlinearity in vessel roll time series. Lastly, Lyapunov exponent calculations are performed to detect chaotic behavior resulting from nonlinear vessel motions coupled with the dynamics of fluid sloshing in on-board tanks. The nonlinear time series analysis programs contained in the TISEAN package [1] are used extensively throughout this work.
A New Implicit Integration Scheme for the Simulation of Stiff-Complex Mechanical Systems
Authors: Oghbaei Mojtaba , Anderson Kurt S.
Published: June 2008

When performing the dynamic simulation of stiff mechanical systems, implicit type integration schemes are usually required to preserve stability. This article presents a new implicit time integrator, which is a particular application of a novel state-time formulation recently developed by the authors in a more general scope. The proposed scheme is constructed with the intent of benefitting from the accuracy and apparent robustness thus far achieved with this algorithm in an integration context. This is realized by first setting up the weighted residual form of the governing equations of the system in a form associated with the application of a time marching integration scheme. The resulting algebraic equations are then solved, minimizing the error of integration time step in a generalized energy sense, allowing one to capture the stiff behavior of solution in an efficient manner. Examples are provided to show the proposed method performance when dealing with a stiff system.
A State-Time Formulation for Multibody Systems Dynamics Simulation: Part II — Parallel Implementation
Authors: Oghbaei Mojtaba , Anderson Kurt S. , Evans John A.
Published: June 2008

This paper outlines the parallel implementation of a newly developed multibody system dynamics formulation. The methodology provides the means for the dynamic simulation to be parallelized temporally as well as spatially which will allow better exploitation of anticipated massively parallel computing resources. This will have three advantages: First, the system of equations may now be coarse grain parallelized to a far greater degree allowing an increased number of processors to be effectively utilized. Secondly, this will significantly reduce the fraction of serial operations and thus should increase speedup (reduced turn-around). Finally, the method allows temporal scale of each variable to be adjusted independently and as such offer considerable advantage for the efficient and accurate modeling and simulation of multiscale behaviors. These gains can be accomplished by discretizing a special form of the equations of motion in both temporal and spatial domains. Examples are provided to clarify the application of this scheme with particular attention on time domain parallelization.
Dynamic Analysis of the Vehicle Running on Turnout at High Speed Considering Longitudinal Variation of Rail Profiles
Authors: Kono Hiroyuki , Suda Yoshihiro , Yamaguchi Masahiro , Yamashita Hiroshi , Yanobu Yukihide , Tsuda Kazunori
Published: June 2008

Recently, railroad systems are getting increased worldwide attention in order to reduce environmental pollution and traffic jam. The railway systems are light rail transit systems in city or high-speed railroad systems between cities. Up to now, dynamic behavior of the vehicle running on a turnout at high speed was NOT researched. In this research, dynamic behavior of the vehicle running on turnout at high speed was calculated using A’GEM (Multi-Body Dynamics program), which was developed to enable to calculate the longitudinal variation of cross-section of rail profiles with vehicle running on turnout which has tongue rails and crossing rails. This paper shows the analysis method and the results of dynamic simulation of the vehicle running on a turnout at high speed considering longitudinal variation of rail profiles.
Nonlinear Vibrations of Elastic Structures Carrying Two Rectangular Liquid-Filled Tanks Under Horizontal Excitation
Authors: Ikeda Takashi
Published: June 2008

Nonlinear vibrations of an elastic structure carrying two liquid-filled tanks under horizontal harmonic excitation are investigated. When a 1:1:1 ratio of internal resonance is satisfied among the natural frequencies of the structure and sloshing in the two liquid tanks, modal equations are derived by using Galerkin’s method, taking into account the nonlinearity of the hydrodynamic force. Then, frequency response curves are calculated by using Andronov and Witt’s method. Peculiar vibrations, referred to as ‘multi-mode vibrations’, sometimes may appear depending on the values of the system parameters. They never occur in a structure carrying only one liquid-filled tank. In other words, even if the dimensions of the two tanks are identical, the sloshing which occurs in each tank differs depending on the excitation frequency. The multi-mode vibrations include constant amplitude vibrations and amplitude modulated motion as well as chaotic vibrations.