bluuebunny/crossref_metadata_2025 huggingface dataset:
Wave Propagation and Band-Gap Characteristics of Chiral Lattices
Authors: Gonella Stefano , Spadoni Alessandro , Ruzzene Massimo , Scarpa Fabrizio
Published: May 2009

Plane wave propagation in a chiral lattice is investigated through the application of Bloch’s theorem. Two-dimensional dispersion relations are estimated and analyzed to illustrate peculiar properties of chiral or non-centrosymmetric configurations and investigate the directional behavior of wave propagation for varying geometric parameters. Special attention is devoted to the determination of phase and group wave velocities. Considerations based upon the analysis of velocity plots are compared with results obtained from dispersion curves to further validate the directional behavior of the proposed lattice. Finally, The relation of directionality with frequency of the traveling waves is discussed.
Modelling of Viscous Squeeze-Film Damping and the Edge Correction for Perforated Microstructures Having a Special Pattern of Holes
Authors: Homentcovschi Dorel , Cui Weili , Miles Ronald N.
Published: May 2009

This paper contains an analysis of the squeeze-film damping in micro-electromechanical devices having a planar microstructure containing a repetitive pattern of oval holes. The planar microstructures containing oval holes assure a better protection against dust particles and water drops than the microstructures having circular holes. Consequently, they should be preferred in designing protective surfaces for microphones working in natural environment. Analytical formulas are provided for designing a planar microstructure with a periodic system of staggered holes to create a structure having minimum squeeze-film damping with an assigned open area. For the planar microstructures containing aligned oval holes an edge correction is given which accounts for the finite size of real structures.
Software for the Kinematic Synthesis of Coupler-Driven Spherical Four-Bar Mechanisms
Authors: Grimm Eric M. , Murray Andrew P. , Turner Michael L.
Published: May 2009

A spatial analogue of the Stephenson III six-bar mechanism can be formed by the connection of an SPS chain to the coupler of a spherical four-bar linkage. With the prismatic joint actuated, the spherical four-bar is driven via a force applied directly to the coupler. This linkage is termed the coupler-driven spherical four-bar mechanism, and defines an alternative to the typical scheme of actuating the four-bar via a torque applied at the input link. This paper presents software developed to assist in the kinematic synthesis of these mechanisms. In the first stage of the design, a circuit-defect free spherical four-bar is dimensioned with the capacity to guide a rigid body through two orientations. The second stage of the design is to locate the SPS leg such that the four-bar is smoothly drivable between the orientations.
Bifurcation Analysis of a One DOF Rotor on Electromagnetic Bearings
Authors: Nataraj C. , Marx Steven
Published: May 2009

This paper considers a one degree of freedom rotor supported on an electromagnetic bearing in a feedback control loop. A nonlinear model of an electromagnetic bearing is developed and a nondimensional model is derived for the system with two distinct parameters corresponding to the controller gain and the static load. Nonlinear analysis is carried out as a function of these two parameters and bifurcation diagrams are derived. The results reveal a very interesting panoply of fixed points with varying stability conditions. Numerical simulations are carried out to confirm the results of nonlinear analysis. Practical implications of the nonlinear analysis results are discussed.
Rational Motion Interpolation Under Kinematic Constraints of Spherical 6R Closed Chains
Authors: Purwar Anurag , Jin Zhe , Ge Q. J.
Published: May 2009

The work reported in this paper brings together the kinematics of spherical closed chains and the recently developed freeform rational motions to study the problem of synthesizing rational interpolating motions under the kinematic constraints of spherical 6R closed chains. The results presented in this paper are extension of our previous work on the synthesis of piecewise rational spherical motions for spherical open chains. The kinematic constraints under consideration are workspace related constraints that limit the position of the links of spherical closed chains in the Cartesian space. Quaternions are used to represent spherical displacements. The problem of synthesizing smooth piecewise rational motions is converted into that of designing smooth piecewise rational curves in the space of quaternions. The kinematic constraints are transformed into geometric constraints for the design of quaternion curves. An iterative algorithm for constrained motion interpolation is presented that detects the violation of the kinematic constraints by searching for those extreme points of the quaternion curve that do not satisfy the constraints. Such extreme points are modified so that the constraints are satisfied and the resulting new points are added to the ordered set of the initial positions to be interpolated. An example is presented to show how this algorithm produces smooth spherical rational spline motions that satisfy the kinematic constraints of a spherical 6R closed chain. The algorithm can also be used for the synthesis of rational interpolating motions that approximate the kinematic constraints of spherical 5R and 4R closed chains within a user-defined tolerance.
The Development of a Continuum Hydraulic/Pneumatic Actuator for Enhancing Gripping Function
Authors: Fronczak Frank , Johnson Alwyn , Randall Scott , Ferrier Nicola
Published: May 2009

This paper describes a research project being conducted to develop a flexible actuator to be used in orthotic and robotic devices. A unique Continuum Hydraulic/Pneumatic Actuator (CHPA) has been designed at the University of Wisconsin-Madison Fluid Power Research Laboratory (UW-FPRL). As the name suggests, the CHPA can be hydraulically or pneumatically energized to produce a pushing force. The actuator is being developed to flex fingers to assist the gripping capability of persons who have a combination of diminished strength and motor control. The CHPA is implemented within a powered hand orthosis (PHO) and can feasibly be used with end effectors. A glove-like, non-bulky, and non-patient specific PHO prototype was fabricated to be used in conjunction with the actuator. Test results indicate that with component development and improved fabrication methods, the performance of the CHPA can be optimized for common gripping tasks. At an operating pressure of 120 psi (830 kPa) an actuator 0.35 inches (9 mm) in diameter and 4.5 inches (114 mm) in length provides (distal) pushing forces between 5–6 pounds (22–27 N) and produces corresponding (palmar) finger-tip forces in the range of 2–5 pounds (9–22 N). Future efforts will focus on optimizing the CHPA mechanism, it’s configuration within the orthosis and integrating a suitable control interface.
Geometric Optimization of a Piezoelectric Power Harvesting Plate for Increased Bandwidth
Authors: Wells Lee , Lin Yirong , Sodano Henry , Youn Byeng
Published: May 2009

The continual advances in wireless technology and low power electronics have allowed the deployment of small remote sensor networks. However, current portable and wireless devices must be designed to include electrochemical batteries as the power source. The use of batteries can be troublesome due to their limited lifespan, thus necessitating their periodic replacement. Furthermore, the growth of battery technology has remained relatively stagnant over the past decade while the performance of computing systems has grown steadily, which leads to increased power usage from the electronics. In the case of wireless sensors that are to be placed in remote locations, the sensor must be easily accessible or of disposable nature to allow the device to function over extended periods of time. For this reason the primary question becomes how to provide power to each node. This issue has spawned the rapid growth of the energy harvesting field. Energy scavenging devices are designed to capture the ambient energy surrounding the electronics and convert it into usable electrical energy. The concept of power harvesting works towards developing self-powered devices that do not require replaceable power supplies. However, when designing a vibration based energy harvesting system the maximum energy generation occurs when the resonant frequency of the system is tuned to the input. This poses certain issues for their practical application because structural systems rarely vibrate at a signal frequency. Therefore, this effort will investigate the optimal geometric design of two dimensional energy harvesting systems for maximized bandwidth. Topology and shape optimization will be used to identify the optimal geometry and experiments will be performed to characterize the energy harvesting improvement when subjected to random vibrations.
Robust and Accurate Boolean Operations on Polygonal Models
Authors: Chen Yong
Published: May 2009

We present a new sampling-based method for the efficient and reliable calculation of boundary surface defined by a Boolean operation of given polygonal models. We first construct uniform volumetric cells with sampling points for each geometric element of polygonal models. We then calculate an error-minimizing point in each cell based on a quadratic error function (QEF). Based on a novel adaptive sampling condition, we construct adaptive octree cells such that a QEF point in each cell can capture the shape of all the geometric elements inside the cell. Finally we reconstruct a polygonal model from the volumetric grids and QEF points for approximating the boundary of a solid defined by the Boolean operation. Our method is robust since we can handle different types of topological inconsistency including non-manifold configurations. It is also accurate since we guarantee the boundary approximation has the same topology as the exact surface, and the maximum approximation error from the exact surface is bounded by a user specified tolerance. The efficient hierarchical scheme based on octree enables using sufficient grid resolutions on a commodity PC. We demonstrate our algorithm for a number of test cases and report experimental results.
An Energy-Based Approach to the Dynamics of Impacts in Unilaterally-Constrained Multibody Systems
Authors: Modarres Najafabadi Seyed Ali , Ko¨vecses Jo´zsef , Angeles Jorge
Published: May 2009

This paper introduces a novel approach to dynamics analysis of contacts involving multibody systems, and particularly the case of simultaneous multiple-point impact. This approach is based on an analysis of energy absorption and restitution during impact, using a decomposition technique, which exactly decouples the kinetic energy associated with the normal and tangential directions of the contact pairs. Such decomposition leads to a generalized definition of the energetic coefficient of restitution, which allows for consideration of simultaneous multiple-point contact scenarios. The main advantages of this new definition and the potential applications of the said technique are highlighted.
Interactive Image Processing and Manipulation
Authors: Nestinger Stephen S. , Cheng Harry H.
Published: May 2009

Electronic imaging informatics spans a diverse range of applications. These applications would benefit from an interpretive imaging platform, which allows dynamic manipulation and processing of electronic images. Ch is an embeddable C/C++ interpreter that provides an interpretive platform for C/C++ based scripts and programs. Combining Ch with ImageMagick provides the functionality for rapid development of user defined image manipulation and processing applications and scripts. The presented Ch ImageMagick package provides users with the ability to interpretively execute C code based on the ImageMagick C library. This article describes the integration of ImageMagick and Ch. The use of ImageMagick utilities in Ch scripts for rapid prototyping is illustrated. A Web-based example demonstrates the use of Ch and ImageMagick in C based CGI scripting to facilitate the development of Web-based applications involving image manipulation and processing.
A Function-Based Approach for Integrated Design of Material and Product Concepts
Authors: Messer Matthias , Panchal Jitesh H. , Allen Janet K. , McDowell David L. , Mistree Farrokh
Published: May 2009

Designing advanced multifunctional materials and products in an integrated fashion starting from the conceptual stage provides designers with increased flexibility to achieve system performance goals that were not previously achievable. Today however, product designers commonly select more or less advanced materials from selection charts or catalogs, rather than designing them along with the product from the conceptual stage on. In order to increase a designer’s flexibility in the conceptual stage and render conceptual materials design more systematic, hence less ad-hoc and intuitive, the main contribution is the development of a systematic approach to the integrated design of material and product concepts from a systems perspective. This systematic approach is focused on developing multilevel function structures, including the material levels. Based on functional analysis, abstraction and synthesis, multiscale phenomena and associated governing solution principles are mapped to functional relationships. Hence, multilevel function structures are embodied into principal solution alternatives based on comprehensive identification and integration of phenomena and associated governing solution principles occurring at multiples levels and time and length scales. In this paper, the function-based approach to integrated design of material and product concepts is illustrated through the systematic design of reactive material containment system concepts. Having developed an overall reactive material containment system function structure, a more detailed function structure on the materials level is created. For dominating functional relationships at the materials level, governing solution principles are identified on multiple scales. The most promising solution principles are then classified in morphological charts. Combining solution principles in a systematic fashion including the materials level, product and material system concepts are identified. The most promising system concepts, in other words the principal solution alternatives that narrow the gap to desired system performance goals, are selected and illustrated in concept selection charts. A selected material and product system concept is then characterized in terms of its specific properties, which are to be tailored to the functional requirements and performance goals in subsequent embodiment design processes. By developing concepts of the product and material as an integrated system, materials design becomes more systematic and hence less ad-hoc and intuitive. At the same time, designers are enabled to realize new functionality and achieve system performance goals that were not previously achievable.
Flexible and Reconfigurable Systems: Nomenclature and Review
Authors: Ferguson Scott , Siddiqi Afreen , Lewis Kemper , de Weck Olivier L.
Published: May 2009

The demands on today’s products have become increasingly complex as customers expect enhanced performance across a variety of diverse and changing system operating conditions. Reconfigurable systems are capable of undergoing changes in order to meet new objectives, function effectively in varying operating environments, and deliver value in dynamic market conditions. Research in the design of such responsive and changeable systems, however, currently faces impediments in effective and clear discourse due to ambiguity in terminology. Definitions of the terms flexibility and reconfigurability, two related concepts in reconfigurable system design, are explored based on their original lexical meanings and current understanding in design literature. Design techniques that incorporate flexibility both in the design (form) and performance (function) space are presented. Based upon this literature survey, a classification scheme for flexibility is proposed, and its application to reconfigurable system design is explored. This paper also presents recent methodologies for reconfigurable system design and poses important research questions that remain to be investigated.
Creative and Supporting Cognitive Modes
Authors: Wilde Douglass J. , Kim Sohyeong
Published: May 2009

The psychiatrist Carl G. Jung has asserted that the “creative impulse” — the drive to solve problems — is almost an instinct on a par with hunger, sex drive, aggression and flight from danger. Unlike the instincts, however, creativity can be extinguished or can atrophy from disuse. Jung’s personality theory identifies eight “cognitive modes” which channel the creative impulse in different directions for various people. A given person’s “creative mode” — the most conscious — can be identified by the four-letter code of the Myers-Briggs Type Indicator (MBTI®). Of the remaining seven modes, as many as three “supporting” modes can be found by simple calculation using the four “clarity index” numbers associated with the MBTI® letters. Although these supporting modes are not the “creative” one, they back it up during problem-solving and at Stanford have been found useful for forming, organizing and analyzing student design teams.
Development of Paper Feeding Speed Control System Using Co-Simulation Tool
Authors: Cha Ho-Young , Yun Duk-Jin , Rhim Sungsoo , Lee Soon-Geul
Published: May 2009

Recently, the demand of a high speed and high accuracy increases in the media transport (or feeding) system (MTS) which is one of the most essential parts in copiers, digital printers, ATM’s and so forth. This paper illustrates the development of a high-speed, high-accuracy paper feeding system including a feedback feeding speed control system with a learning controller. The controller is designed to reduce the slippage between the feeding rollers and paper in the presence of the periodic disturbance in the nip force of the driven roller which is mainly caused by the eccentricity of the driven roller. The lack of an accurate model of the plant often makes control system designers to face difficulties at an early stage in designing a robust controller for highly non-linear multi-body dynamics system such as the MTS with flexible media. To mitigate the problem, a so-called co-simulation approach, the combination of a controller development tool and a model developed in MBD, is often adopted and it would allow the controller designer to expedite the design and evaluation of control systems. In the paper, using a co-simulation approah a MTS with a paper is modeled and a repetitive learning controller is develped and evaluated.
Analysis of Energy Harvesting Devices Using Macro-Fiber Composite Materials
Authors: Song Hyun Jeong , Choi Young-Tai , Wereley Norman M. , Purekar Ashish S.
Published: May 2009

This paper addresses modeling, design, theoretical and experimental characteristics of an energy harvesting device utilizing macro-fiber composite (MFC) materials. The energy harvesting device is composed of a cantilever beam with MFC materials, a tip mass, a rectifier, and an electrical resistance. An theoretical model of the energy harvesting device is established for estimation of generated power, voltage, and current under sinusoidal base excitation at its first natural frequency. Parametric studies are achieved to maximize generated power and current with variation of beam thickness, natural frequency, type of MFC and electrical resistance. Also, performance characteristics of the energy harvesting device with two MFC patches are theoretically and experimentally evaluated under different acceleration levels.
Impact of Tooth Friction and Its Bending Effect on Gear Dynamics
Authors: Liu Gang , Parker Robert G.
Published: May 2009

This work studies the influences of tooth friction on parametric instabilities and dynamic response of a single-mesh gear pair. A mechanism whereby tooth friction causes gear tooth bending is shown to significantly impact the dynamic response. A dynamic translational-rotational model is developed to consider this mechanism together with the other contributions of tooth friction and mesh stiffness fluctuation. An iterative integration method to analyze parametric instabilities is proposed and compared with an established numerical method. Perturbation analysis is conducted to find approximate solutions that predict and explain the numerical parametric instabilities. The effects of time-varying friction moments about the gear centers and friction-induced tooth bending are critical to parametric instabilities and dynamic response. The impacts of friction coefficient, bending effect, contact ratio, and modal damping on the stability boundaries are revealed. Finally, the friction bending effect on the nonlinear dynamic response is examined and validated by finite element results.
Application of Product Platform Design for Engineered System
Authors: Goswami Mohit , Allada Venkat
Published: May 2009

The focus of this paper is on the design of the engineered system comprising various subsystems that have functional interactions amongst themselves. Depending on the system architecture, subsystems can be classified into one of the two types: scalar and modular subsystems. Each subsystem is defined by various primary and secondary parameters, performance criteria, and compatibility constraints. The objective function is formulated as minimization of total cost of all the subsystems while meeting the required performance criteria. The cost of an individual subsystem is a function of parameters of that particular subsystem. The complete engineered system level problem has been formulated as a non linear programming optimization problem. The application of the proposed methodology is demonstrated using an example of the automotive truck family.
Product Development Task Planning Using Worth Flow Analysis of Interacting Components
Authors: Miwa Toshiharu , Ishii Kosuke
Published: May 2009

The acceleration of product development cycle continues to be a significant challenge for manufacturing firms around the world. This paper describes a task planning method for minimizing trial and error to reduce the development time in large-scale and complicated product development at the early stage of product development. The proposed method matches the group of product components according to geometry and determines the development sequence of each component to minimize the amount of feedback information across task groups. The method applies as evaluation index for task prioritization the product-sum of engineering interaction among components and worth of each component, the “worth flow.” The paper shows with an example of the generic hair drier with simple mechanical structure that this method contributes to the reduction of the size of task group by 22% and amount of information required for setting the interface links by 65% compared to the conventional planning methods.
Amplified Piezoelectric Stack Actuators for Harvesting Electrical Energy From a Backpack
Authors: Feenstra Joel , Granstrom Jonathan , Sodano Henry A.
Published: May 2009

Over the past few decades the use of portable and wearable electronics has grown steadily. These devices are becoming increasingly more powerful, however, the gains that have been made in the device performance has resulted in the need for significantly higher power to operate the electronics. This issue has been further complicated due to the stagnate growth of battery technology over the past decade. In order to increase the life of these electronics, researchers have begun investigating methods of generating energy from ambient sources such that the life of the electronics can be prolonged. Recent developments in the field have led to the design of a number of mechanisms that can be used to generate electrical energy, from a variety of sources including thermal, solar, strain, inertia, etc. Many of these energy sources are available for use with humans, but their use must be carefully considered such that parasitic effects that could disrupt the user’s gait or endurance are avoided. This study develops a novel energy harvesting backpack that can generate electrical energy from the differential forces between the wearer and the pack. The goal of this system is to make the energy harvesting device transparent to the wearer such that his or her endurance and dexterity is not compromised. This will be accomplished by replacing the strap buckle with a mechanically amplified piezoelectric stack actuator. Piezoelectric stack actuators have found little use in energy harvesting applications due to their high stiffness which makes straining the material difficult. This issue will be alleviated using a mechanically amplified stack which allows the relatively low forces generated by the pack to be transformed to high forces on the piezoelectric stack. This paper will develop a theoretical model of the piezoelectric buckle and perform experimental testing to validate the model accuracy and energy harvesting performance.
Perturbation Analysis of a Clearance-Type Nonlinear System
Authors: Zhu Farong , Parker Robert G.
Published: May 2009

This study applies the method of multiple scales to obtain periodic solutions of a two-pulley belt system with clearance-type nonlinearity. The purpose is to explain the published numerical results and clarify how design parameters affect the system dynamics. The validity of the perturbation method for such strong nonlinearity is evaluated. The closed-form frequency response relation is determined at the first order, and an implicit expression is obtained for the second order approximation. The preload applied to the accessory determines the softening level of the nonlinearity. Larger preload leads to less disengagement and less softening. For a considerable range of practical parameter values, the analytical solutions well approximate the numerical results from harmonic balance.
A Compliant Rotating Joint for Deployable Wings on Small UAVs
Authors: Landon Steven D. , Magleby Spencer P. , Jensen Brian D.
Published: May 2009

Recent interest in small Unmanned Air Vehicles (UAVs) has led to advances in wing technologies. Deployable wings reduce required storage space while providing greater range during flight. This paper presents a compliant rotating joint which is bistable and features a locking characteristic that prevents the wing from reverting back to the undeployed configuration during flight. The two stable positions occur at local strain energy minima about 90 degrees apart, but can be adjusted by the designer. A pseudo rigid body model is illustrated for the joint, based on a four-bar linkage. Such a joint mechanism can be designed for any wing, by using the pseudo rigid body model to optimize link lengths and position the instant center appropriately. In addition, the mechanism can be cut out within a single plane for ease of manufacture and assembly.
Flexural-Torsional Buckling of Misaligned Axially Moving Beams: Vibration and Stability Analysis
Authors: Orloske Kevin , Parker Robert G.
Published: May 2009

This paper addresses the stability and vibration characteristics of three-dimensional steady motions (equilibrium configurations) of translating beams undergoing boundary misalignment. System modeling and equilibrium solutions for bending in two planes, torsion, and extension were presented in a previous work [1]. Stability is determined by linearizing the equations of motion about a steady motion and calculating the eigenvalues using a finite-difference discretization. For the case of no misalignment, the calculated eigenvalues are compared to known values. When the beam is misaligned, the system initially enters a planar configuration and the results indicate that the planar equilibria lose stability after the first bifurcation point. Eigenvalue behavior of the planar equilibria after the first bifurcation point is shown to be strongly influenced by translation speed. Eigenvalue behavior about non-planar equilibria and vibration modes about selected equilibria are also presented.
Product Reverse Engineering Based on Growth Design Process
Authors: Huang Kezheng
Published: May 2009

Current reverse engineering approach is an effective way for technology progress of developing countries. Based on analysis of existing reverse engineering technology, a new concept of Product Reverse Engineering (PRE) is proposed and its theoretical framework is discussed first in this paper in order to extend its application from components to the overall product structure and design process. Then a brief introduction is made to the technical system architecture and key techniques for PRE, which include the rapid solid modeling, integrating with existing CAD systems through STEP file, assembly modeling for conceptual structure, and reverse design process reconstruction. Finally, a prototype system PRE-DARFAD is developed with initial verification by a fixture design example.
Application of Incomplete Gamma Functions to the Initialization of Fractional-Order Systems
Authors: Hartley Tom T. , Lorenzo Carl F.
Published: May 2009

This paper reviews some properties of the gamma function, particularly the incomplete gamma function and its complement, as a function of the Laplace variable s. The utility of these functions in the solution of initialization problems in fractional-order system theory is demonstrated.
Mixed Integer Optimization With NURBs HyPerModels
Authors: Turner Cameron J. , Crawford Richard H. , Campbell Matthew I.
Published: May 2009

The challenge of determining the best design in a multimodal design space with multiple local optimal solutions often challenges the best available optimization techniques. By casting the objective function of the optimization problem in the form of a Non-Uniform Rational B-spline (NURBs) metamodel, known as a HyPerModel, significant optimization advantages can be achieved, including the ability to efficiently find the global metamodel optimum solution with less computational expense than traditional approaches. This optimization strategy, defined by the HyPerOp algorithm, uses the underlying structure of a HyPerModel to intelligently select starting points for optimization runs and to identify regions of the design space that do not contain locations for the global metamodel optimum location. This paper describes the application of the HyPerOp algorithm to mixed integer programming problems and demonstrates its use with two example applications. The algorithm works with design spaces composed of continuous and integer design variables and provides a complementary approach for improved optimization capabilities.
Experimental Identification of a Shear-Mode MR Damper and Numerical Evaluation of Hysteretic Models
Authors: Zapateiro Mauricio , Luo Ningsu , Taylor Ellen , Dyke Shirley J.
Published: May 2009

Magnetorheological (MR) dampers have become an effective means for the semiactive vibration control of civil structures. For achieving good control performance, it is necessary to make the accurate characterization of the civil structures to be controlled, the sensors, the actuators and some other systems integrated. Nowadays, the modeling and identification of the dynamics of an MR damper is still a challenging task due to its highly hysteretic nonlinearities. This paper presents experimental results on the modeling and identification of a type of MR damper prototype whose MR fluid is contained in a foam. A comparative study is made among three parametric models (Bingham, Bouc-Wen and Hyperbolic tangent).
Primary Resonance of a Duffing Oscillator With Two Distinct Time Delays in State Feedback Under Narrow-Band Random Excitation
Authors: Jin Yanfei , Hu Haiyan
Published: May 2009

The primary resonance of a Duffing oscillator with two distinct time delays in state feedback under narrow-band random excitation is investigated in detail by using the method of multiple scales. First, the equations of modulation of response amplitude and phase are determined. Then, the expressions of the first-order and the second-order steady-state moments and their stable regions are obtained by introducing the equivalent detuning frequency and the equivalent damping ratio. For the case of two distinct time delays, the appropriate choices of the combinations of the feedback gains and the difference between two time delays are discussed from the viewpoint of vibration control. Finally, the theoretical analyses are well verified through numerical simulations.
Chaos in a Discrete Dynamic Model of Traffic Flow
Authors: Xu Meng , Gao Ziyou
Published: May 2009

This paper aims to discuss unstable traffic flow and to identify if chaotic phenomena exist in a traffic flow dynamic system. Two discrete dynamic models are proposed, which are derived from the flow-density-speed fundamental diagram and Del Castillo and Benitez’s exponential curve model and maximum sensitivity curve model. Both the models have two parameters, which are the ratio of free flow and spacing average speed and the ratio of the absolute value of kinematic wave speed at jam density and free flow speed. Chaos is found in the two models when the two values increase separately. The Liapunov exponents were used to examine the characters of the chaotic behavior in the two models. These results are illustrated by numerical examples.
Experimental Validation of a Computerized Tool for Face Hobbed Gear Contact and Tensile Stress Analysis
Authors: Piazza Andrea , Vimercati Martino
Published: May 2009

While face milled gears have been widely analyzed, about face hobbed ones only very few studies have been developed and presented. Goal of this paper is to propose the validation of an accurate tool, which was presented by the authors in previous works, aimed to the computerized design of face hobbed gears. Firstly, the mathematical model able to compute detailed gear tooth surface representation on both spiral and hypoid gears will be briefly recalled; then, the so obtained 3D tooth geometry is employed as input for an advanced contact solver that, using a hybrid method combining finite element technique with semianalytical solutions, is able to efficiently carry out both contact analysis under light or heavy loads and stress tensile calculation. The validation analyses will be carried on published aerospace face hobbed spiral bevel gear data comparing measurements of root and fillet stresses. Good agreement with experimental results both in the time scale and in magnitude will be revealed.
A Variable Fidelity Model Management Framework for Multiscale Computational Design of Continuous Fiber SiC-Si3N4 Ceramic Composites
Authors: Meji´a Rodri´guez Gilberto , Renaud John E. , Tomar Vikas
Published: May 2009

Research applications involving design tool development for multiple phase material design are at an early stage of development. The computational requirements of advanced numerical tools for simulating material behavior such as the finite element method (FEM) and the molecular dynamics method (MD) can prohibit direct integration of these tools in a design optimization procedure where multiple iterations are required. The complexity of multiphase material behavior at multiple scales restricts the development of a comprehensive meta-model that can be used to replace the multiscale analysis. One, therefore, requires a design approach that can incorporate multiple simulations (multi-physics) of varying fidelity such as FEM and MD in an iterative model management framework that can significantly reduce design cycle times. In this research a material design tool based on a variable fidelity model management framework is presented. In the variable fidelity material design tool, complex “high fidelity” FEM analyses are performed only to guide the analytic “low-fidelity” model toward the optimal material design. The tool is applied to obtain the optimal distribution of a second phase, consisting of silicon carbide (SiC) fibers, in a silicon-nitride (Si3N4) matrix to obtain continuous fiber SiC-Si3N4 ceramic composites (CFCCs) with optimal fracture toughness. Using the variable fidelity material design tool in application to one test problem, a reduction in design cycle time around 80 percent is achieved as compared to using a conventional design optimization approach that exclusively calls the high fidelity FEM.
Maintenance Strategy Development Within SME’s: The Development of an Integrated Approach
Authors: Baglee David , Trimble Robert , MacIntyre John
Published: May 2009

The importance of maintenance has increased, as high productivity and quality can be achieved by means of well-developed and organised maintenance strategies. However, this assumes that maintenance is controlled in such a way that equipment is stopped for maintenance via a systematic schedule. With the recent advances in technology many methodologies, tools, techniques and strategies have been developed and tested. Unfortunately, the majority of organisations are constrained by certain barriers with the resulting loss of major benefits. These are usually classified as Small and Medium Sized Enterprises (SMEs). Based upon our data analysis a new maintenance methodology, the Advanced Integrated Maintenance Management System (AIMMS) is developed. To enable the implementation, monitoring and evaluation of AIMMS a computerised system — Maintenance Management (MainMan) — was developed and implemented within several case study companies. This paper examines the implementation process within one of these companies. The results indicate that AIMMS supports strategic maintenance decisions, and helps to increase equipment effectiveness through prioritising equipment criticality and focusing on specific resources that will maximise gains based upon a return on investment.
Fatigue and Fracture Mechanics in Products Development for Railroad Vehicles
Authors: Sakamoto Haruo
Published: May 2009

Railroad products suffer fatigue since they are used in a condition of cyclic loading when railroad vehicles run. Key products are the most important mechanical parts, which are wheels, axles, discs, and truck frames. They are such fail-out components, as can cause the fatal failure of vehicles, when the components fail. Among such components, wheels and axles are the most critical railroad components, since they can cause the derailment. Tremendous efforts to the research and development have been devoted in the area of railroad industry. However, the rail accident of German railroad in 1998 clarified that we need to study more deeply. Fracture Mechanics are now used as an ordinary tool to apply to design products, and knowledge of fatigue characteristics is common. This paper summarizes how the railroad product in Japan were developed using the knowledge of fatigue characteristics and fracture mechanics, and considers the future research. The issues are whether fatigue limit exists based on the scientific explanation, whether the retardation of crack extension can happen with appropriate ground, and whether a crack extends under large compressive cyclic loading. The author had engaged in the area for 35 years, and the summary adding such experience is explained.
Seat/Head Restraint System Robust Design for IIHS Rear Impact
Authors: Fu Yan , Weng T. C.
Published: May 2009

The Insurance Institute for Highway Safety (IIHS) announced the procedures to evaluate and rate rear crash protection system, which focus on how well seat/head restraint system protects against soft tissue neck (“whiplash”) injury. The “Good” rating for IIHS rear impact combining with the “Good” ratings of both frontal offset and side impacts, plus offering electronic stability control will earn the Institute’s “Top Safety Pick” award. The goal of this work is to develop an analytical and efficient way to assist engineers in analyzing the design variables of the seat/head restraint system to improve the IIHS rear impact rating. An integrated robust design method for IIHS rear impact is developed using design of experiments, variable screening, response surface method, and genetic algorithm. A CAE simulation model with Bio-RID dummy is built to correlate to rear impact sled tests. The correlated model is then used in the robust design study to identify design strategy and obtain robust design to maximize the chance of achieving IIHS rear impact “Good” rating. The proposed robust design method is applied to a manual seat/head restraint system to achieve robust design under various noise factors. The results demonstrate that the integrated robust design method is a useful tool to improve the seat and head restraint system design to improve IIHS rear impact rating.
A Customizable Human/Vehicle Interface for Enhanced Operator Performance
Authors: Jensen Matthew , Wagner John , Alexander Kim , Pidgeon Philip
Published: May 2009

The emergence of cost effective electronics and actuators within the transportation industry allows the presentation of increased driver feedback for greater situational awareness. The operator feedback channels can be broadly divided into visual, audio, and haptic. To date, the automotive community has primarily relied on instrument panel lamps and buzzer/chime sounds to notify the driver of important information while the vehicle’s interaction with the road is mechanically communicated through the steering wheel “feel” and the driver seat motion. However, an opportunity exists to integrate the visual, audio, and haptic feedback channels in a more effective manner to increase driver safety. For instance, the driver may receive haptic driving information through high frequency and low amplitude steering wheel vibrations. Visual feedback may be presented in the form of LED lights on the dashboard and instrument cluster. Similarly, audio messages that are recognized through a different cognitive process than visual and haptic signals may be integrated into the cockpit. In this paper, a comprehensive approach is proposed for driver communication through visual, audio, and haptic feedback. Laboratory tests have been conducted with human subjects using a custom driving simulator to evaluate driver notification strategies. The effectiveness of each feedback channel is evaluated and the results demonstrate that the coordinated presentation of vehicle operational data through targeted feedback channels increase the operator’s overall safety.
Development of a Longitudinal Vehicle Controller via Hardware-in-the-Loop Simulation
Authors: Baek Woonhyuk , Song Bongsob , Song Hoin
Published: May 2009

In this paper, a longitudinal vehicle controller is proposed for an active driver safety system and its validation via Hardware-In-Loop Simulation (HILS) is presented. Since the desired speed and distance are chosen arbitrarily by a driver, there are usually discontinuities or discrete jumps between the desired and current vehicle state right after the desired input is changed. To minimize performance degradation resulting from this discrete jump, one of nonlinear control techniques, Dynamic Surface Control (DSC) with an input-shaping filter, is applied for both velocity and distance control. Furthermore, while much cost and effort are in general required for experimental validation of the longitudinal controller, its validation via HILS is performed with a better efficiency. Finally, various switching scenarios including discrete desired inputs in terms of velocity and distance are considered and the corresponding performances of the controller are shown in the HILS.
Validation of a New Aluminum Honeycomb Crush Model With Dynamic Impact Tests
Authors: Hinnerichs Terry , Scherzinger William , Nielsen Mike , Carne Tom , Stasiunas Eric , Lu Wei-Yang
Published: May 2009

This paper describes a process for validating a new constitutive model for large, high strain-rate deformation of aluminum honeycomb, called the Honeycomb Crush Model (HCM). This model has 6 yield surfaces that are coupled to account for the orthotropic behavior of the cellular honeycomb being crushed on-axis and off-axis. The HCM has been implemented in the transient dynamic Presto finite element code for dynamic impact simulations. The HCM constitutive parameters were identified based on Presto finite element models that were used to simulate uniaxial and biaxial crush tests of 38 lb/ft3 aluminum honeycomb and reported in an earlier paper. This paper focuses on validating the HCM in the Presto code for application to impact situations that have honeycomb crush velocities up to 85 ft/sec. Also, a new approach for incorporating rate sensitivity into the model is described. A two-stage energy absorber with integrated aluminum honeycomb is described as the configuration for dynamic impact validation experiments. The test parameters and finite element model will be described along with the uncertainty quantification that was done and propagated through the model. Finally, correlation of model predictions and test results will be presented using an energy based validation metric.
Dynamic Modeling of Heavy-Duty Hybrid Electric Vehicles
Authors: Serrao Lorenzo , Hubert Christopher J. , Rizzoni Giorgio
Published: May 2009

The paper presents a dynamic model of a hybrid electric powertrain for a heavy-duty vehicle. The model involves all powertrain components and considers purely longitudinal vehicle dynamics; time constants of 0.05 – 5 seconds are taken into account, thus neglecting high frequency phenomena (NVH, engine cylinder-to-cylinder motion). Integration with handling dynamics models, characterized by the same frequency range, is possible but not discussed here. The simulator is an accurate virtual test bench for energy management strategies applied to hybrid electric powertrains, capable of predicting both fuel consumption and dynamic performance. The accuracy in both metrics is demonstrated by comparison with experimental data collected on a conventional heavy-duty refuse truck and a prototype of a series hybrid electric version of the same vehicle.