bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrating Multiple Engineering Resources in a Virtual Environment for Reverse Engineering Legacy Mechanical Parts
Authors: Musuvathy Suraj R. , Johnson David E. , de St. Germain H. James , Cohen Elaine , Xu Chimiao , Riesenfeld Richard F. , Henderson Thomas C.
Published: June 2008

Reverse engineering is a time-consuming and technically formidable process that is increasingly becoming an economic imperative due to replacement costs. The Multiple Engineering Resources aGent Environment (MERGE) system, introduced in this paper, is a new approach toward reverse engineering whose architecture and modules are driven specifically by the requirements of legacy engineering. Legacy engineering scenarios presume availability of multiple (possibly incomplete or inconsistent) sources of information, lack of digital descriptions of the parts, constrained time restrictions and need for significant domain knowledge expertise. The reverse engineering process must yield modern CAD models capable of driving state-of-the art CAM processes. The MERGE system aims at making the reverse engineering process more effective, using both intuitive interaction and visualization as key components, by enabling quick identification and resolution of inconsistencies among various resources in a unified environment. The MERGE system also aims at simplifying the reverse engineering process by integrating various computational agents to assist the reverse engineer in processing information and in creating the desired CAD models.
Modeling and Experimental Verification of Frictional Contact-Impact in Loose Bolted Joint Elastic Structures
Authors: Foster J. T. , Barhorst A. A. , Wong C. N. , Bement M. T.
Published: June 2008

In this paper a dry frictional contact-impact model of two elastic beams joined by a loose bolted joint is developed and compared to experimental data. The model utilizes the concept of instantly applied non-holonomic constraints and pseudo-speeds to provide the variable structure hybrid parameter dynamical equations for the system. Simulation logic is developed and presented in outline form. An experimental apparatus is described. Simulation results and experimental results are compared and discussed.
Network-Based Vehicle Collision Detection and Simulation
Authors: Wu Liangshou , Oliver James , Sannier Adrian
Published: June 2008

Vehicle driving simulation, collision detection, and collision simulation of rigid bodies are not new concepts in physical-based simulations, but the integration of all these techniques is a challenging and interesting topic. This paper implements a network-based vehicle collision detection and response simulation system that has all the components that are required by a vehicle driving simulation. It supports vehicle-to-scene and vehicle-to-vehicle collision detection and response simulation in real-time required by a human-in-the-loop driving simulation. Additionally, it supports collaborative driving simulations for multiple vehicles in the same virtual environment operated from different physical locations. A network-based collision server is developed to provide consistent and realistic collision response for vehicles that collide. Implementation testing shows that the network-based collision simulation can provide a real-time, realistic and robust system in a network with relatively small time lags, such as a LAN or a city-wide network. The implementation has demonstrated it can support simultaneous collision simulation with up to 32 vehicles operating at 150miles/h in a high speed local area network.
Modeling and Analysis of a Vibratory Micro-Pin Feeder Using Impulse-Based Simulation
Authors: Weir Nathan A. , Cipra Raymond J.
Published: June 2008

A variety of methods exist for the assembly of microscale devices. One such strategy uses microscale force-fit pin insertion to assemble LIGA parts together. One of the challenges associated with this strategy is the handling of small pins which are 170 microns in diameter and with lengths ranging from 500 to 1000 microns. In preparation for insertion, a vibratory micro-pin feeder has been used to successfully singulate and manipulate the pins into a pin storage magazine. This paper presents the development of a deterministic model, simulation tool, and methodology in order to identify and analyze key performance attributes of the vibratory micro-pin feeder system. A brief parametric study was conducted to identify the effects of changing certain system parameters on the bulk behavior of the system, namely the capture rate of the pins. Results showing trends have been obtained for a few specific cases. These results indicate that different system parameters can be chosen to yield better system performance.
Influence of Torsional Motion on Vibratory Drilling
Authors: Gouskov Alexander M. , Voronov Sergey A. , Kvashnin Alexey S. , Butcher Eric A. , Sinha S. C.
Published: June 2008

The nonlinear dynamics of a tool commonly employed in deep hole drilling is analyzed. The tool is modeled as a two-degree of freedom system that vibrates in axial directions and twists caused by the cutting process. The mechanical model of cutting forces is a nonlinear function of cutting tool displacement including state variables with time delay. The equations of new surface formation are separated as a specific set. These equations naturally include the regeneration effect of oscillations under cutting and it is possible to analyze continuous and intermittent cutting involving either stationary or non-stationary processes. The vibratory drilling tool feed consists of a constant as well as a periodic component. The influence of tool axial and torsional dynamics on chip formation is considered. The Poincare maps of state variables for various sets of operating conditions are presented. The obtained results allow prediction of conditions for stable continuous cutting and unstable regions. The conditions of tool axial vibrations synchronized at frequency of external excitation are analyzed. The time domain simulation allows determination of the chip shape most suitable for certain workpiece material and tool geometry. It is also shown that disregarding tool torsional vibrations may significantly change the chip formation process. The suggested model can be applied at the stage of the manufacturing process design.
A Study on the Feed Rate Optimization of a Ball Screw Feed Drive System for Minimum Vibrations
Authors: Choi Young H. , Hong Jin H. , Jang Sung H.
Published: June 2008

In order to prevent machine tool feed slide system from transient vibrations during operation, machine tool designers usually adopt some typical design solutions; box-in-box typed feed slides, optimizing moving body for minimum weight and dynamic compliance, and so on. Despite all efforts for optimizing design, a feed drive system may experience severe transient vibrations during high-speed operation if its feed-rate control is not suitable. A rough feed-rate curve having discontinuity in its acceleration profile causes serious vibrations in the feed slides system. This paper presents a feed-rate optimization of a ball screw driven machine tool feed slide system for its minimum vibrations. A ball screw feed drive system was mathematically modeled as a 6-degree-of-freedom lumped parameter model. Then, a feed-rate optimization of the system was carried out for minimum vibrations. The main idea of the feed-rate optimization is to find out the most appropriate smooth acceleration profile having jerk continuity. A genetic algorithm, G.A., was used in this feed rate optimization.
A Packing Genetic Algorithm for Configuration Design
Authors: Miao Yi , Fadel Georges M.
Published: June 2008

Solving packing problems corresponds to finding the optimal placement of a series of objects in an enclosed space, while satisfying functional requirements. The research presented in this paper proposes a “packing GA” designed especially for the packing problems. It differs from the traditional GA by its encoding method and GA operators, which are tailored for the configuration design problem. In this paper, the detailed implementation and the design principles of the packing GA are presented. To evaluate the effectiveness of the proposed algorithm, a strict definition of acceptable layout is given, so that the performance of the GA can be judged by a more meaningful criterion. The packing GA is tested against two other GAs on an 8 box packing problem. The results show the packing GA has a much better chance to find the global optimum.
Equilibrium and Vibration Analysis of a Fabric Web Under Arbitrary Large Deformation
Authors: Ma Zheng-Dong , Jiang Dongying
Published: June 2008

A new formulation for a three-dimensional thread is presented in this paper, which can be used for equilibrium and vibration analyses of a fabric web or a cable network system under arbitrary large deformation. This formulation is in a very compact form, compared with the existing formulations, but it accounts for the extensibility of the thread, geometry nonlinearity, tension variation along the thread, and other nonlinear effects due to the large deformation of the thread. A major contribution of the current paper is the development of incremental forms of the equilibrium and vibration equations, which can be used for obtaining numerical solutions using, for example, a finite element method, without further simplifications. The incremental form equations have been solved with several numerical examples that demonstrate the effectiveness of the new formulation developed.
Towards a Theory of Experimentation for Expected Improvement
Authors: Frey Daniel D. , Wang Hungjen
Published: June 2008

This paper concerns the role of experimentation in engineering design, especially the process of making improvements through parameter design. A simple mathematical model is proposed for studying experimentation including a model of adaptive one-factor-at-a-time experimentation. Theorems are proven concerning the expected value of the improvement provided by adaptive experimentation. Theorems are also proven regarding the probability that factor effects will be exploited by the process. The results suggest that adaptive one-factor-at-a-time plans tend to exploit two-factor interactions when they are large or otherwise exploit main effects if interactions are small. As a result, the adaptive process provides around 80% of the improvements achievable via parameter design while exploring a small fraction of the design alternatives (less than 20% if the system has more than five variables).
Use of Learned Velocity Profile for Media Transport System
Authors: Rhim Sungsoo , Lee Sung-Whan , Kim Si-Eun , Lee Soon-Geul
Published: June 2008

The media-transport system (MTS) is a key component in many daily appliances for example copiers, printers and ATMs. The slippage between the medium and the feeding rollers in the MTS results in the irregular feeding speed of the medium and deteriorates the performance of the whole system. This paper focuses on the regulation of the paper feeding velocity by applying the adequate command profile to the driving roller. To learn the required command profile for the driving rollers, a repetitive learning controller is introduced. For the development and the evaluation of the control system two-dimensional simulation model for the MTS where a paper sheet medium is modeled as a multi-body dynamic system. The simulation was performed in a co-simulation environment where two analysis tools are used in a symbiotic manner. Simulations results show improved feeding performance by using the learned driving velocity profile.
Does Sketching Skill Relate to Good Design?
Authors: Cham Jorge G. , Yang Maria C.
Published: June 2008

Sketching is an activity that takes place throughout the engineering design process, and is often linked to design cognition. This preliminary study identifies different skills that contribute to a designer’s sketching ability and explores how those skills might be related to sketch fluency and design outcome. A positive correlation was found between the quantity of sketches produced and sketch skills that emphasize drawing facility, but a negative correlation was found between sketch quantity and a skill related to mechanism visualization. Sketching is sometimes considered a generic skill, but this study suggests that there are differences among the different types of sketching skills in the context of engineering design. No notable relationship was found between sketching ability and design outcome. Results also suggest that students provided with explicit instruction in sketching tended to draw more overall, although there are likely many other factors involved.
Infused Creativity: An Approach to Creative System Design
Authors: Shai Offer , Reich Yoram , Rubin Daniel
Published: June 2008

Many methods that support human creativity by manual or computational means have been proposed in the past. They rely on the assumption that following a certain process of reasoning might lead to generating ideas considered creative. We start by defining creativity as a capability that enables the creation of systems that are patentable. Subsequently, we present a method called infused creativity, which is derived from infused design. The method guarantees generating creative designs by transforming systems from remote disciplines. Finding these systems and their transformations is done through a provably guaranteed to work process based on the underlying discrete mathematical representation. We describe the method of infused creativity and illustrate its operation in designing a new active torque amplifier system. We also discuss the future development of the method.
Automating Error Attenuation of Cutting Tools Using Smart Material
Authors: Rashid Maki K. , Al-Shabibi Abdullah M.
Published: June 2008

Vibration attenuation techniques in cutting tools can save old machines and enhance design flexibility in new manufacturing systems. The finite element method is employed to investigate structural stiffness, damping, and switching methodology under the use of smart material in tool error attenuation. This work discusses the limitations of using lumped mass modeling in toolpost dynamic control. Transient solution for tool tip displacement is obtained when pulse width modulation (PWM) is used for smart material activation during the compensation of the radial disturbing cutting forces. Accordingly a Fuzzy algorithm is developed to control actuator voltage level toward improved dynamic performance. The required minimum number of PWM cycles in each disturbing force period is investigated to diminish tool error. Time delay of applied voltage during error attenuation is also evaluated. Toolpost static force-displacement diagram as required to predict voltage intensities for error reduction is tested under different dynamic operating conditions.
Optimisation of a Robotic Workcell Layout Using Genetic Algorithms
Authors: Sim Siang-Kok , Tay Meng-Leong , Khairyanto Ahmad
Published: June 2008

With the advent of robots in modern-day manufacturing workcells, optimization of robotic workcell layout (RWL) is crucial in ensuring the minimization of the production cycle time. Although RWL share many aspects with the well-known facility layout problem (FLP), there are features which set the RWL apart. However, the common features which they share enable approaches in FLP to be ported over to RWL. One heuristic gaining popularity is genetic algorithm (GA). In this paper, we present a GA approach to optimizing RWL by using the distance covered by the robot arm as a means of gauging the degree of optimization. The approach is constructive: the different stations within the workcell are placed one by one in the development of the layout. The placement method adopted is based on the spiral placement method first broached by Islier (1998). The algorithm was implemented in Visual C++ and a case study assessed its performance.
Feature Recognition Using Combined Convex and Maximal Volume Decompositions
Authors: Wang Eric , Kim Yong Se , Woo Yoonhwan
Published: June 2008

Next generation process planning systems should be capable of dealing with industrial demands of versatility, flexibility, and agility for product manufacturing. Development of process planning system is heavily dependent on feature recognition, but presently there is no satisfactory feature recognition system relying on a single method. In this paper, we describe a hybrid feature recognition method for machining features that combines three feature recognition technologies: graph-based, convex volume decomposition, and maximal volume decomposition. Based on an evaluation of the strengths and weaknesses of these methods, we integrate them in a sequential workflow, such that each method recognizes features according to its strengths, and successively simplifies the part model for the following methods. We identify two anomalous cases arising from the application of maximal volume decomposition, and discuss their cure by introducing limiting halfspaces. All recognized features are combined into a unified hierarchical feature representation, which captures feature interaction information, including geometry-based machining precedence relations.
Identification of Modal Damping Ratios for a Simplified Wind Turbine Tower Using Fourier Analysis
Authors: Murtagh Paul J. , Basu Biswajit , Broderick Brian M.
Published: June 2008

This paper presents an approach to evaluate the modal damping ratios for a simplified wind turbine tower, using Fourier analysis and linear regression. The model proposed for the wind turbine tower is composed of a flexible tower and rotor blade system, inter-connected using a sub-structuring technique, which facilitates the rotating blade/tower coupling. A model order reduction technique is first used to model each of the two sub-structures (tower/nacelle and rotor system) as single degree-of-freedom systems. The free vibration characteristics of the tower include the effects of a large nacelle mass at the towers free end, and the corresponding properties of the rotating blades include the effects of centrifugal stiffening and axial self-weight, due to rotation. Then, the two reduced order sub systems are then coupled together to form an equivalent two degree-of-freedom coupled tower/blade wind turbine tower model. A wind-induced forced vibration analysis of the coupled tower/blades model is carried out using artificially generated wind drag time-histories obtained as discrete Fourier transform representations of wind drag power spectral density functions. From this analysis, a method is proposed, based on Fourier analysis and the linear regression, to solve the inverse problem for evaluating the first and second modal damping ratios of the coupled system. A numerical example is presented in order to demonstrate the applicability of the proposed approach, where excellent agreement was observed between the originally specified modal damping ratios and the subsequently estimated ones. The proposed method can be extended to obtain the equivalent damping of the system with soil interaction and including aerodynamic damping.
Boundary Effect and Weld Reinforcement of Large Opening With Flush Nozzle in Ellipsoidal Head Pressure Vessel
Authors: Guo Chongzhi , Chen Wenxin
Published: June 2008

By the analysis of the single and double boundary effect of the large opening structure with flush nozzle in pressure vessel with ellipsoidal head in terms of Thin Shell Theory, stress distribution of the two cases are obtained in this paper. Then numerical and experimental verifications are carried out by finite element method (FEM) and experiments. Comparing theoretic and numerical results with experimental data respectively; it is found that FEM or theoretic results accord with the experimental data well, while there is some non-consistence between the FEM or theoretic results and the experimental data within joint range. According to the consistence between the analysis results of FEM and those of thin shell theory in weld roots, a newly weld reinforce effect calculation approach of the welt joint is proposed by considering the size of the weld joint and using the results of thin shell theory in the roots of the weld. Example presented indicates that, as a quick and convenient evaluation means, using the results of thin shell theory in weld root to evaluate joint strength is available and reliable.
A Complete Variation Algorithm for Slot and Tab Features for 3D Simulation-Based Tolerance Analysis
Authors: Shen Zhengshu , Shah Jami J. , Davidson Joseph K.
Published: June 2008

Development of tolerance analysis methods that are consistent with the ASME and ISO GD&T (geometric dimensioning and tolerancing) standards is a challenging task. Such methods are the basis for creating computer-aided tools for 3D tolerance analysis and assemblability analysis. These tools, along with the others, make it possible to realize virtual manufacturing, in order to shorten lead-time and reduce cost in the product development process. Current simulation tools for 3D tolerance analysis and assemblability analysis are far from satisfactory because the underlying variation algorithms are not fully consistent with the GD&T standards. Better algorithms are still to be developed. Towards that goal, this paper proposes a complete algorithm for 3D slot features and tab features (frequently used in mechanical products) for 3D simulation-based tolerance analysis. The algorithms developed account for bonus/shift tolerances (i.e. effects from material condition specifications), and tolerance zone interaction when multiple tolerances are specified on the same feature. A case study is conducted to demonstrate the algorithm developed. The result from this work is compared with that from 1D tolerance chart method. The comparison study shows quantitatively why 1D tolerance chart method, which is popular in industry, is not sufficient for tolerance analysis, which is 3D in nature.
Design of Swept Blade for Turbomachinery
Authors: Xu C. , Amano R. S.
Published: June 2008

To meet the needs of efficient turbine blade designs, CFD predictions of a complex 3D flow field in turbine blade passages have been incorporated in the design process during the last decade. Owing to the numerous advantages possessed by a 3-D CFD technology many industries already use a 3D blading technique in the design process of turbomachines. In addition, blade lean and sweep have been implemented to increase the blade row efficiency. Experimental studies have shown some advantages of these features. However, most of the experimental results were combined with other features together as well; thus making it difficult to determine the effects of individual superior features. The development of CFD techniques has made it possible to do three-dimensional turbulent flow analyses in a very short time. In this study, numerical studies are presented to demonstrate the sweep effects on a transonic compressor airfoil. The purpose of this study is to investigate the sweep effects without changing other compressor blade features; i.e. keeping the blade outflow angles and section shapes to be the same at design sections for all cases. Through this study the sweep effect in a transonic compressor rotor blade was tested. The results showed that the sweeps redistribute the flow reducing the secondary flow loss, depending on the baseline. It was shown that the forward sweep reduces the tip loading in terms of the static pressure coefficient.
Application of Multibody Dynamics to On-Orbit Manipulator Simulations
Authors: Quiocho Leslie J. , Huynh An , Crues Edwin Z.
Published: June 2008

This paper discuses a generic multibody dynamics formulation and associated computer algorithm that addresses the variety of manipulator simulation requirements for engineering analysis, procedures development, and crew familiarization/training at the NASA Johnson Space Center (JSC). The formulation is based on body to body relationships with no concept of branched tree topologies. This important notion results in a single recursion pass to construct a system level mass matrix as opposed to the traditional inbound/outbound passes required by the other recursive methods. Moreover, the formulation can be augmented to account for closed loop topologies. The base body of the structure can be fixed or free; each subsequent body, if any, is attached to its parent body via any combination of rotational or translational degrees of freedom (DOFs). Furthermore, each body in the multibody system can be defined as rigid or flexible. The algorithm is designed to partition the data variables and associated computations for multi-frequency or multi-process computation. The resulting algorithm requires approximately one third the computations (in terms of additions and multiplications) of techniques previously used at the NASA JSC.
A Graph-Based Method for Mechanical Product Family Modeling and Functional Tolerancing
Authors: Wang Haoyu , Roy Utpal
Published: June 2008

To meet the needs for product variety, many companies are shifting from a mass production mode to mass customization, which demands quick response to the needs of individual customers with high quality and low costs. One of the key elements of mass customization is that the product family can share some modules. The multifunction nature of mechanical components necessitates designers to redesign them each time a component’s function changes. This is the main obstacle to the practical mechanical product family modeling. In this paper, a graph grammar based mechanical product family modeling method is proposed. The other issue that is studied in this paper is tolerancing, which is a critical part of the product design process because it is intimately related to a product’s quality and costs. A functional tolerance specification method, called the mirror method, is proposed to provide guidelines for the component’s datum reference frame construction and generic and uniform functional tolerance specifications.
Dynamic Behaviour of a Light Trailer Chassis
Authors: Grison Vagner , Paucar Casas Walter J.
Published: June 2008

In this work numerical tools of simulation are applied to analyze the structural dynamic behavior of a light trailer passing through a secondary highway. After the dynamic analysis of the rigid model is realized, the resultant forces are obtained in the points of attachment between the springs and the chassis. These responses serve as input for a global analysis of the simplified model in a finite element program, making possible the identification of the most critical regions of the structure. Next, a more detailed local model of the critical region is created in order to evaluate singular stress concentration points. This method named global-local serve to obtain detailed results on structural analysis through a reduced number of elements. These results supply important information to the designer, making possible that modifications in the design can be best realized to improve the performance of the product.
Influence of the Wheel and Rail Interpolation Scheme on the Contact Evaluation in Railway Dynamics
Authors: Pombo J. , Ambro´sio J.
Published: June 2008

The dynamic behavior of the railway vehicles is strongly influenced by the complex interaction between the wheels and rails. In conventional rail vehicles the wheelsets are assembled with two wheels that are not free to rotate independently. Hence, their treads are profiled in order to allow them to negotiate curves without slipping. The dynamics of guidance depends on the wheel-rail contact forces resultant from the vehicle interaction with the track. In this work a methodology for the accurate geometric description of track models is proposed in the framework of multibody dynamics. It includes the representation of the track spatial geometry and its irregularities. The wheel and rail surfaces are parameterized with a formulation that allows using any wheel and rail profiles obtained from direct measurements or design requirements. A methodology is proposed to find online the coordinates of the contact points between wheel and rail surfaces, even for the most general three dimensional motion of the wheelset. A formulation for the description of the normal contact forces, which result from the wheel-rail interaction, is also presented. The tangential creep forces in the wheel-rail contact area are evaluated using: Kalker linear theory; Heuristic force method; Polach formulation. All methodologies proposed here are implemented in a general multibody code. The advantages and drawbacks of the computational tool are discussed with emphasis on the influence of the interpolation scheme used to parameterize the wheel and rail profiles. The discussion is supported through the dynamic analysis of the wheelset of the railway vehicle ML95 on a straight track.
An Efficient Method for a Category of Contact/Impact Problems in Multibody Systems: Tree Topologies
Authors: Sadowski Michael J. , Anderson Kurt S.
Published: June 2008

This paper presents an algorithm for the efficient numerical analysis and simulation of a category of contact/impact problems in multi-rigid-body dynamic systems with tree topologies. The algorithm can accommodate the jumps in structure which occur in the equations of motion of general multi-rigid-body systems due to a contact/impact event between bodies, or due to the locking of joints as long as the resulting system is a tree topology. The presented method uses a generalized momentum balance approach to determine the velocity jumps which take place across impacts in such multibody dynamic systems where event constraint forces are of the “non-working” category. The presented method does not suffer from the performance (speed) penalty encountered by most other momentum balance methods given its O(n) overall cost, and exact direct embedded consideration of all the constraints. Due to these characteristics, the presented algorithm offers superior computing performance relative to other methods in situations involving both large n and potentially many unilateral constraints.
VE-Suite: A Software Framework for Design-Analysis Integration During Product Realization
Authors: Xiao Angran , Bryden Kenneth Mark , McCorkle Douglas S.
Published: June 2008

Product realization is a complex decision-making process requiring intensive interactions between engineers, especially between designers and analysts. It is necessary to develop effective tools to help them manage the heterogeneous software tools, multidisciplinary engineering models, and information flows during the process. Multidisciplinary analysis results must be synthesized with the design models to support designers making decisions based on an overall understanding about the product’s performance. Meanwhile, along the product realization timeline, these tools, models, and information must be constantly updated and modified. In this paper, we present a flexible software framework, VE-Suite, to handle the “two-dimensional” characteristics of design-analysis integration. The data structure and communication mechanism in VE-Suite enable convenient design-analysis integration not only across the boundary of disciplines, but also along the product realization timeline. An ongoing design scenario of a hydraulic mixing nozzle is presented; some temporary results are introduced to demonstrate the significance of the two-dimensional integration and the effectiveness of the VE-Suite.
A Feature-Based Approach to Embedded System Hardware and Software Co-Design
Authors: Zha Xuan F. , Fenves Steven J. , Sriram Ram D.
Published: June 2008

An embedded system is a hybrid of hardware and software that combines software flexibility and hardware real-time performance. The co-design of hardware and software is the most critical but difficult issue in embedded system design. In this paper, we propose a novel feature-based approach to the co-design of hardware (HW) and software (SW) in embedded systems. The approach first defines an extension to the NIST Core Product Model and then provides an object-oriented UML (Unified Modeling Language) representation for the embedded system feature model, including models of embedded system artifacts, components, features, and HW/SW configuration/assembly. The extended model provides a feature-based HW/SW component co-design framework allowing the designer to develop a virtual embedded system prototype through assembling virtual components. The resulting feature-based model serves as the basis for developing reusable and adaptable components/artifacts. The underlying SW and HW components are determined through feature configuration, and thus HW/SW co-design is implemented by using feature-component mapping and component generation, which may be associated with feature creation, configuration, analysis and reuse. A case study example is discussed to illustrate the embedded system model.
Topological Synthesis for Linkage Mechanism Design Using the Minimum Potential Energy Principle
Authors: Gea Hae Chang , Kwon Jaehyun
Published: June 2008

A mechanism is a device transmits motion in a predetermined manner in order to accomplish specific objectives. Mechanism design can be divided into three steps: type synthesis, number synthesis and dimensional synthesis, where the number synthesis is also called topological synthesis. In this paper, a new approach for topological synthesis and dimensional synthesis of linkage mechanism design with pin joints is presented. This approach is based on the discrete element approach which always provides clear definitions of number of linkages and joints. In order to extend its applications beyond the compliant mechanism, a novel analysis method based on the principle of minimum potential energy for linkage topology optimization is employed. Unlike the traditional FEM based approaches, this novel analysis method can be applied to multiple joint linkage designs directly. Genetic Algorithm is chosen as the optimizer. Finally, a few design examples from the proposed method are presented.
Decision Analysis Approach for Improving Product Development Decision Quality: An Interactive Simulation Game Showcase
Authors: Yang Tae G. , Ishii Kosuke , Karandikar Harshavardhan
Published: June 2008

Product development decisions in the early stages of the development process critically impact life cycle cost and revenue potentials. Design for Manufacturability tools and methods provide key insights into product’s requirements based on the voice of customers. Other quantitative analysis tools, such as computer aided modeling and optimization techniques enhance product developers’ understanding in the products under development. However, the dynamic nature of product development process suffers from unavoidable risks due to the lack of information on key parameters of a product’s life cycle. This paper introduces the fundamentals of Decision Analysis applicable to product development process as a way of dealing with dynamic product development risks. The application of specific tools is shown via a simulation game based on a robot platform development case. We summarize the lessons learned, and conclude on how decision analysis principles could be used for the platform/product design process.
A Hybrid Analytical, Solid Modeler and Feature-Based Methodology for Extracting Tool-Workpiece Engagements in Turning
Authors: Zhou Jing , Yip-Hoi Derek , Huang Xuemei
Published: June 2008

In order to optimize turning processes cutting forces need to be accurately predicted. This in turn requires accurate extraction of the geometry of tool-workpiece engagements (TWE) at critical points during machining. TWE extraction is challenging because the in-process workpiece geometry is continually changing as each tool pass is executed. This paper describes research on a hybrid analytical, solid modeler and feature-based methodology for extracting TWEs generated during general turning. While a pure solid modeler based solution can be developed it will be shown that because of the ability to capture different cutting tool inserts with similar geometry and to model the process in 2D, an analytical solution can be used instead of the solid modeler in many instances. This leads to more efficient computation during extraction. Further, by identifying features in the removal volumes where the engagement conditions are not changing or changing predictably additional enhancements in the efficiency of the TWE extraction can be achieved. The methodology developed will be demonstrated in extracting engagements for a typical industrial component. TWE extraction is one component in a Virtual Machining system currently under development.
Structural Topology Optimization Under Design-Dependent Loads
Authors: Zheng Bin , Gea Hae Chang
Published: June 2008

In this paper, topology optimization of structure subject to design-dependent loads is studied. The position and direction of the design-dependent loads will change as the shape and topology of structure changes during optimization iteration. A potential function is introduced to locate the surface boundary. Design sensitivity analysis is derived. Examples from the proposed method are presented.
An Engineering Shape Benchmark for 3D Models
Authors: Iyer Natraj , Jayanti Subramaniam , Ramani Karthik
Published: June 2008

Three dimensional shape searching is a problem of current interest in several different fields, especially in the mechanical engineering domain. There has been a large body of work in developing representations for 3D shapes. However, there has been limited work done in developing domain dependent benchmark databases for 3D shape searching. In this paper, we propose a benchmark database for evaluating shape based search methods relevant to the mechanical engineering domain. Twelve feature vector based representations are compared using the benchmark database. The main contributions of this paper are development of an engineering shape benchmark and an understanding of the effectiveness of different shape representations for classes of engineering parts.
Propagation Properties of Three-Coupled Periodic Mechanical Systems
Authors: Romeo Francesco , Paolone Achille
Published: June 2008

General three-coupled periodic systems are dealt with by means of transfer matrices of single units. The solutions of the associated characteristic equation are discussed in terms of invariant quantities by exploiting the well-known reversibility of its coefficients. An exhaustive description of the free wave propagation patterns is given on the invariants’ space where propagation domains with qualitatively different character are identified. Afterwards, two three-coupled periodic mechanical models are considered: pipes and truss beams. A nonlinear mapping from the invariants’ space to the physical parameters plane provides with a concise representation of the pattern of the propagation domains. A mechanical interpretation associated with the boundaries of these regions is given. The analyzed models give rise to equations of motion where the three-coupled nature stems from the coupling between longitudinal (mono-coupled) and transversal (bi-coupled) dynamics. The evolution of the propagation properties when the coupling parameters tend to vanish is eventually discussed.
Control of Nonlinear Time-Periodic Systems Via Feedback Linearization
Authors: Zhang Yandong , Sinha S. C.
Published: June 2008

The problem of designing controllers for nonlinear time periodic systems is addressed. The idea is to find proper coordinate transformations and state feedback under which the original system can be (approximately) transformed into a linear control system. Then a controller can be designed using the well-known linear method to guarantee the stability of the system. We propose two approaches for the feedback linearization of the nonlinear time periodic system. The first approach is designed to achieve local control of nonlinear systems with periodic coefficients desired to be driven either to a periodic orbit or to a fixed point. In this case the system equations can be represented by a quasi-linear system containing nonlinear monomials with periodic coefficients. Using near identity transformations and normal form theory, the original close loop problem is approximately transformed into a linear time periodic system with unknown gains. Then by using a symbolic computation method, the Floquet multipliers are placed in the desired locations in order to determine the control gains. We also give the sufficient conditions under which the system is feedback linearizable up to the rth order. The second approach is a generalization of the classical exact feedback linearization method for autonomous systems but applicable to general time-periodic affine systems. By defining a time-dependent Lie operator, the input-output nonlinear time periodic problem is transformed into a linear autonomous problem for which control system can be designed easily. A sufficient condition under which the system is feedback linearizable is also given.
Active Control of Shock
Authors: Nishimura Hidekazu , Wang Dezhang , Amano Yoichi , Shimogo Taro
Published: June 2008

In this paper we deal with active control of shock in a collision problem between two objects. In order to make it clear how the deformation of the shock-receiving object can be maximized while minimizing the deformation of the shock-giving object and how energy can be transmitted unilaterally, the relationships among contact stiffness, deformation time, deformation ratio and energy balance are discussed. The final-state control is applied to obtain a feedforward input to deform the shock-receiving object by a desired amount in a predetermined time. Thus, the energy balance and the energy efficiency are verified. Furthermore we examine the conditions necessary to realize a ‘dynamical diode’ that can transmit energy unilaterally from the shock-giving object to the shock-receiving object. It is demonstrated experimentally that the appropriate feedforward input can be obtained by final-state control under specified conditions of contact stiffness and deformation time.
Vibration Analysis and Health Monitoring of Cracks in Composite Disk Rotor Systems
Authors: Hai Xin , Flowers George , Horvath Roland , Fausz Jerry
Published: June 2008

Cracks and voids are common defects in rotating systems and are a precursor to fatigue-induced failure. Identifying the presence and growth of cracks is a critical concept for the health monitoring and diagnostics of such systems. A combined computational and experimental study of the vibration characteristics of a composite hub flywheel rotor system with a cracked hub disk is presented. First, experimental testing of both in-plane and out-of-plane vibration characteristics using a rotor with a composite disk hub supporting a relatively massive rim was conducted. A crack was deliberately introduced into the hub disk during fabrication. Based upon these results, a finite element (FEA) model was developed to further explore the relationship between natural frequencies and crack properties. Finally, a simplified theoretical model for the primary in-plane vibration mode was developed and used in a series of parametric studies. Good agreement was found between the model predictions and the experimental results. It was observed that the presence of a crack tends to affect both the magnitudes and distribution of the rotor natural frequencies. Certain primary frequencies for rotors with a crack are smaller than for those without a crack. In addition, the frequency values of associated with the “in-crack” direction are generally smaller than those associated with the “off-crack” direction, introducing a non-symmetry into the rotordynamics which can serve as an indicator for rotor health monitoring.
An Optimal Control Algorithm for Suppression of Harmonic Base Excitation in Nonlinear Magnetic Bearings
Authors: Marx Steven , Nataraj C.
Published: June 2008

The paper deals with rotor systems that suffer harmonic base excitation when supported on magnetic bearings. Magnetic bearings using conventional control techniques perform poorly in such situations mainly due to their highly nonlinear characteristics. The compensation method presented here is a novel optimal control procedure with a combination of conventional, proportional and differential feedback control. A four degree of freedom model is used for the rotor system, and the bearings are modeled by nonlinear expressions. Each disturbance frequency is exprcted to produce a multi-harmonic system response, a characteristic of nonlinear systems. We apply optimal control choosing to minimize a performance index, which leads to the optimization of the trigonometric coefficients in the correction current function. Results show that the control technique suppresses rotor vibration to amplitudes that were significantly smaller than the disturbance amplitudes for the entire range of disturbance frequencies applied. The control technique explored in this paper is a promising step towards the successful application of magnetic bearings to systems mounted on moving platforms.
Sound Quality Testing and Analysis of Multiple Brands of Sewing Machines
Authors: Chatterley James J. , Boone Andrew J. , Lago¨ Thomas L. , Blotter Jonathan , Sommerfeldt Scott D. , Smith Craig C.
Published: June 2008

Sound quality analysis is an invaluable tool for the product designer. This tool is designed to help determine customer preferences, which can help the designer improve product quality, or the consumers’ perception of the product’s quality. Many industries desire to know how the consuming public perceives their product as this affects the product life and viability. This paper will present which of two brands of sewing machines ranging in market segments from entry-level, thru mid-level machines, to high-end computer controlled units, is the most acoustically pleasant. Results across market segments independent of brand will be evaluated and compared, as well. The methods used to determine the sound quality of these machines will be presented. These methods are both jury based listening tests and quantitative sound quality metrics.
Dynamic Response of Rigid Rotors Supported on Rolling Element Bearings With an Outer Raceway Defect
Authors: Nataraj C. , Pietrusko Robert Gerard
Published: June 2008

This paper is concerned with the nonlinear dynamical response of a rigid rotor supported on rolling element bearings with defects in the outer raceway. The rotor is modeled with five degrees of freedom, and the bearings are modeled with nonlinear forces arising from Hertzian contact stresses. Then we introduce a defect into the roller bearings with a controllable parameter, and analyze the effect of the growth of this defect on the dynamic response of the system using serveral signal processing tools such as spectrum, cepstrum and envelope methods. Numerical results are obtained for a screw compressor rotor. We examine these results with the idea a potential application towards the development of automated condition assessment tools for machinery diagnostics and prognostics. It appears from the results that no single tool is ideal, and that a combination of existing tools could possibly lead to a good strategy.
Non-Jamming Conditions in Multi-Contact Constrained Rigid-Body Dynamics
Authors: Liu Tong , Wang Michael Yu
Published: June 2008

In this paper, we study a rigid body system of one free body (e.g., workpiece) in contact with multiple fixed bodies (e.g., locators). The contacts are unilateral. The investigation is motivated for planning the task of insertion of a workpiece in a fixture. The key issue of the problem is to determine an applied force that can move the workpiece while maintaining all existing contacts with the locators. We first analyze the kinematics of the rigid body constrained by multiple unilateral contacts. The contact constraints are classified into two categories, the configuration constraints and kinematic constraints. We then find a sufficient condition for non-jamming among the multiple contacts in the constrained rigid-body dynamics. This condition is also a necessary condition when the number of contacts is no less than four. Moreover, a method to find the applied force on the workpiece that results in sliding on all contact points is presented, based on the sufficient condition for non-jamming. Numerical examples are presented and the results of the method are compared with the results of a quasistatic method.