bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling Approach for a High Speed Machine Tool Spindle-Bearing System
Authors: Gagnol Vincent , Bouzgarrou Belhassen C. , Ray Pascal , Barra Christian
Published: June 2008

This paper presents a modelling approach of a high-speed spindle-bearing system based on a finite-element model analysis coupled to an experimental modal identification. Dynamic equations of the rotating entity are obtained using Lagrangian formulation associated with a numerical finite element method based on Timoshenko beam theory. Element kinematics is formulated in a co-rotational coordinate frame. A method for the experimental characterization of the dynamic behavior of a High Speed Machining (HSM) spindle is proposed. The goal of this method is to understand the influence of spindle structure elements on overall dynamic behavior. Each element is individually characterized and is integrated or not into the global model depending on the results. The choice of the finite element type for generating the numeric model is carried out on the basis of modal and harmonic experimental results. High-speed rotational effects including gyroscopic coupling and spin softening effects are investigated. The Campbell diagram indicates the potential critical speed for mass unbalance response and for synchronous excitation representative of the milling forces at tooth impact frequency. Excessive vibration levels at specific node location enable spindle component stress or failure during manufacturing processes to be predicted. The model is a useful tool for qualifying spindles in the manufacturing process and predicting their reliability. The proposed modeling approach can be transferred to other type of spindle.
A New Measuring Method of Wheel-Rail Contact Forces
Authors: Matsumoto Akira , Sato Yasuhiro , Ohno Hiroyuki , Tomeoka Masao , Matsumoto Kosuke , Kurihara Jun , Ogino Tomohisa , Tanimoto Masuhisa , Kishimoto Yasushi , Sato Yoshi , Nakai Takuji
Published: June 2008

A new measuring method introduced in this paper can measure contact forces between wheel and rail without special wheelsets with slip rings or telemeters. In this method the lateral contact force is measured from the lateral distortion of wheel measured by several non-contact gap sensors. The measured values are small, but accurate value of lateral force can be calculated by the compensation of axial movement and inclination of wheelset. Normal and longitudinal contact forces are also measured from the strain of parts of the truck except wheelsets. According to the results of full-size truck stand tests and train running tests, we have verified that the new method has sufficient accuracy of measuring compared with conventional methods.
A Cost Based Methodology for Design Optimization
Authors: Rao A. R. , Keane A. J. , Scanlan J. P.
Published: June 2008

Design optimization algorithms have traditionally focused on lowering weight and improving structural performance. Although cost is a vital factor in every emerging design, existing tools lack key features and capabilities in optimizing designs for minimum product cost at acceptable performance levels. This paper presents a novel methodology for developing a decision support tool for designers based on manufacturing cost. The approach focuses on exploiting the advantages offered by combining parametric CAD, Finite element analysis, feature based cost estimation and optimization techniques within a single automated system. This methodology is then applied in optimizing the geometry for minimum manufacturing cost of an engine mounting link from a Rolls-Royce civil aircraft engine.
A Design Optimization Method Using Evidence Theory
Authors: Mourelatos Zissimos P. , Zhou Jun
Published: June 2008

Early in the engineering design cycle, it is difficult to quantify product reliability or compliance to performance targets due to insufficient data or information to model uncertainties. Probability theory can not be therefore, used. Design decisions are usually, based on fuzzy information that is vague, imprecise qualitative, linguistic or incomplete. Recently, evidence theory has been proposed to handle uncertainty with limited information as an alternative to probability theory. In this paper, a computationally efficient design optimization method is proposed based on evidence theory, which can handle a mixture of epistemic and random uncertainties. It quickly identifies the vicinity of the optimal point and the active constraints by moving a hyper-ellipse in the original design space, using a reliability-based design optimization (RBDO) algorithm. Subsequently, a derivative-free optimizer calculates the evidence-based optimum, starting from the close-by RBDO optimum, considering only the identified active constraints. The computational cost is kept low by first moving to the vicinity of the optimum quickly and subsequently using local surrogate models of the active constraints only. Two examples demonstrate the proposed evidence-based design optimization method.
Modeling the Dynamic Frictional Contact of Tires Using an Explicit Finite Element Code
Authors: Wasfy Tamer M. , Leamy Michael J.
Published: June 2008

A time-accurate explicit time-integration finite element code is used to simulate the dynamic response of tires including tire/pavement and tire/rim frictional contact. Eight-node brick elements, which do not exhibit locking or spurious modes, are used to model the tire’s rubber. Those elements enable use of one element through the thickness for modeling the tire. The bead, tread and ply are modeled using truss or beam elements along the tire circumference and meridian directions with appropriate stiffness and damping properties. The tire wheel is modeled as a rigid cylinder. Normal contact between the tire and the wheel and between the tire and the pavement is modeled using the penalty technique. Friction is modeled using an asperity-based approximate Coulomb friction model.
Iterative Learning Velocity and Tension Control for Axially Moving Materials
Authors: Zhao Haiyu , Rahn Christopher D.
Published: June 2008

Precise tension and speed control of axially moving material systems enables high speed processing of paper, plastics, fibers, and films. This paper proves that PD tension/speed control can ensure strong and weak boundedness of distributed displacement and tension, respectively, in a single span axially moving material system. An iterative learning controller (ILC) is proven to provide the same theoretical result but greatly improved simulated response.
Review of Finite Elements Using Absolute Nodal Coordinates for Large-Deformation Problems and Matching Physical Experiments
Authors: Yoo Wan-Suk , Dmitrochenko Oleg , Pogorelov Dmitry Yu.
Published: June 2008

A review of the current state of the absolute nodal coordinate formulation (ANCF) is proposed for large-displacement and large-deformation problems in flexible multibody dynamics. The review covers most of the known implementations of different kinds of finite elements including thin and thick planar and spatial beams and plates, their geometrical description inherited from FEM, and formulations of the most important elements of equations of motion. Much attention is also paid to simulation examples that show the reasonableness and accuracy of the formulation applied to real physical problems and that are compared with experiments having significant geometrical non-linearity. Current and further development directions of the ANCF are also briefly outlined.
On a Control of a Non-Ideal Mono-Rail System With Periodic Coefficients
Authors: Peruzzi N. J. , Balthazar J. M. , Pontes B. R.
Published: June 2008

In this work, the problem in the loads transport (in platforms or suspended by cables) it is considered. The system in subject is composed for mono-rail system and was modeled through the system: inverted pendulum, car and motor and the movement equations were obtained through the Lagrange equations. In the model, was considered the interaction among of the motor and system dynamics for several potencies motor, that is, the case studied is denominated a non-ideal periodic problem. The non-ideal periodic problem dynamics was analyzed, qualitatively, through the comparison of the stability diagrams, numerically obtained, for several motor torque constants. Furthermore, one was made it analyzes quantitative of the problem through the analysis of the Floquet multipliers. Finally, the non-ideal problem was controlled. The method that was used for analysis and control of non-ideal periodic systems is based on the Chebyshev polynomial expansion, in the Picard iterative method and in the Lyapunov-Floquet transformation (L-F transformation). This method was presented recently in [3–9].
On the Inharmonicity of a Struck String
Authors: Nakai Mikio , Kawaguchi Kazuya
Published: June 2008

This paper describes the phenomenon called the inharmonicity for a struck string. It is known that its spectral components consist of two inharmonic peak series: “the first partials” due to the elastic stiffness of a string and “the second partials”. Experimental tests for examining a mechanism of the generation of the second partials were performed with a model of a piano string. The experiments suggest that the second partials are those that have frequencies equal to the sum of the frequencies of a pair of the first partials. Furthermore, numerical simulations were done with nonlinear wave equations involving large string deflection.
The Generalized Cahn-Hilliard Equations of Multiphase Transition for Structural Topology Optimization
Authors: Zhou Shiwei , Wang Michael Yu
Published: June 2008

This paper describes a generalized Cahn-Hilliard model for the topology optimization of multi-material structure. Unlike the traditional Cahn-Hilliard model applied to spinodal separation which only has bulk energy and interface energy, the generalized model couples the elastic energy into the total free energy. As a result, the morphology of the small phase domain during phase separation and grain coarsening process is not random islands and zigzag web-like objects but regular truss structure. Although disturbed by elastic energy, the Cahn-Hilliard system still keeps its two most important properties: energy dissipation and mass conservation. Therefore, it is unnecessary to compute the Lagrange multipliers for the volume constraints and make great effort to minimize the elastic energy for the optimization of structural topology. Furthermore, this model also makes the simple interpolation of stiffness tensors reasonable for multi-material structure in real simulation. To resolve these fourth-order nonlinear parabolic Cahn-Hilliard equations coupled with elastic energy, we developed a powerful mutigrid algorithm. Finally, we demonstrate that this new method is effective in optimizing the topology of multi-material structure through several 2-D examples.
Chaos and Quasi-Periodic Motions on the Homoclinic Surface of Nonlinear Hamiltonian Systems With Two Degrees of Freedom
Authors: Luo Albert C. J.
Published: June 2008

The numerical prediction of chaos and quasi-periodic motion on the homoclinic surface of a 2-DOF nonlinear Hamiltonian system is presented through the energy spectrum method. For weak interactions, the analytical conditions for chaotic motion in such a Hamiltonian system are presented through the energy incremental energy approach. The Poincare mapping surfaces of chaotic motions for such nonlinear Hamiltonian systems are illustrated. The chaotic and quasiperiodic motions on the phase planes, displacement subspace (or potential domains), and the velocity subspace (or kinetic energy domains) are illustrated for a better understanding of motion behaviors on the homoclinic surface. Through this investigation, it is observed that the chaotic and quasi-periodic motions almost fill on the homoclinic surface of the 2-DOF nonlinear Hamiltonian systems. The resonant-periodic motions are theoretically countable but numerically inaccessible. Such conclusions are similar to the ones in the KAM theorem even though the KAM theorem is based on the small perturbation.
A Topology Optimization Problem in Control of Structures Using Modal Disparity
Authors: Diaz Alejandro , Mukherjee Ranjan
Published: June 2008

Towards the goal of developing a new methodology for control of vibration in flexible structures, this paper introduces the concept of modal disparity and addresses the topology optimization problem for maximizing the disparity. The modal disparity in a structure is generated by the application of forces that vary the stiffness of the structure and a topology optimization problem determines the best locations for application of these forces. When the forces are switched on and off and, as a result, the structure is switched between two stiffness states, modal disparity results in vibration energy being transferred from a set of uncontrolled modes to a set of controlled modes. This allows the vibration of the structure to be completely attenuated by removing energy from the small set of controlled modes. Simulation results are presented to demonstrate control of vibration in two truss-like structures exploiting modal disparity.
Preference Consistency in Multiattribute Decision Making
Authors: Kulok Michael , Lewis Kemper
Published: June 2008

A number of approaches for multiattribute selection decisions exist, each with certain advantages and disadvantages. One method that has recently been developed, called the Hypothetical Equivalents and Inequivalents Method (HEIM) supports a decision maker (DM) by implicitly determining the importances a DM places on attributes using a series of simple preference statements. In this and other multiattribute selection methods, establishing consistent preferences is critical in order for a DM to be confident in their decision and its validity. In this paper a general consistency check denoted as the Preference Consistency Check (PCC) is presented that ensures a consistent preference structure for a given DM. The PCC is demonstrated as part of the HEIM method, but is generalizable to any cardinal or ordinal preference structures. These structures are important in making selection decisions in engineering design including selecting design concepts, materials, manufacturing processes, and configurations, among others. The effectiveness of the method is demonstrated and the need for consistent preferences is illustrated using a product selection case study where the decision maker expresses inconsistent preferences.
Can a House Without a Foundation Support Design?
Authors: Olewnik Andrew , Lewis Kemper
Published: June 2008

The House of Quality is a popular tool that supports information processing and decision making in the engineering design process. While its application is an aid in conceptual aspects of the design process, its use as a quantitative decision support tool in engineering design is potentially flawed. This flaw is a result of assumptions behind the methodology of the House of Quality and is viewed as an important deficiency that can lead to potentially invalid and poor decisions. In this paper this deficiency and its implications are explored both experimentally and empirically. The resulting conclusions are important to future use and improvement of the House of Quality as an engineering design tool.
Continuum-Based Design Sensitivity Analysis and Optimization of Springback in Stamping Process
Authors: Choi Kyung K. , Yi Kiyoung , Kim Nam H. , Botkin Mark E.
Published: June 2008

The springback is a significant manufacturing defect in the stamping process. A serious impediment to the use of lighter-weight, higher-strength materials in manufacturing is the relative lack of understanding about how these materials respond to the complex forming process. The springback problem can be reduced by using appropriate designs of die, punch, and blank holder shape together with friction and blank holding force. That is, an optimum stamping process can be determined using a gradient-based optimization to minimize the springback. However, for an effective optimization of the stamping process, development of an efficient analytical design sensitivity analysis method is crucial. In this paper, a continuum-based shape and configuration design sensitivity analysis (DSA) method for the stamping process has been developed. The material derivative concept is used to develop the continuum-based design sensitivity. The design sensitivity equation is solved without iteration at each converged load step in the finite deformation elastoplastic nonlinear analysis with frictional contact, which makes the design sensitivity calculation very efficient. The accuracy and efficiency of the proposed method is illustrated by minimizing springback in an S-rail part, which is often used as an industrial benchmark to verify the numerical procedures employed for stamping processes.
Computing Admissble Transformation Volume
Authors: Qian Xiaoping , Yang Pinghai
Published: June 2008

The ability to quantify part dimensional quality with respect to design specifications is of fundamental importance in product design and manufacturing. Our earlier work has proposed the use of admissible transformation volume as a part dimensional quality metric. That is, part quality is quantified based on how much an as-manufactured part shape can move while still remaining within a tolerance zone. A transformation is admissible if upon such a transformation a manufactured part shape falls within the design tolerance zone. A collection of such transformations in the transformation space forms an admissible transformation volume (ATV). In this paper, we present two properties of ATV: transformation invariant and decomposability. We then describe algorithms for computing ATV and how ATV properties facilitate complex tolerance check and reveal new insight on part producibility.
Stability of High Pressure Turbine Under Partial Admission Condition
Authors: Kanki Hiroshi , Tanitsuji Akinori
Published: June 2008

Subsynchronous vibration of high-pressure steam turbine is one of the difficult problems to improve the reliability of power plant. Extensive work has been done to prevent the low frequency vibration of high-capacity steam turbine and most of the problems were practically solved[1][2]. In the future, we must build up theoretical approach to design a new turbine operating under the steam condition of high-temperature and high-pressure. To design such an advanced steam turbine, it is necessary to solve the effect of partial admission on control stage of the steam turbine. This paper describes the experimental results from the scale model of the steam turbine and theoretical analysis of Alford force considered partial admission condition to solve the problem. (1) Subsynchronous vibration was reproduced in the scale model test. (2) Partial admission gave larger destabilizing force compared with full admission condition for same total flow rate. (3) Initial position of shaft center to the phase of admission arc on the partial admission had some effect on the stability of the rotor system. (4) Theoretical analysis of destabilizing force considered partial admission condition gave qualitative description of the experimental results from the scale model.
Development of Compact Damper Bearing
Authors: Kanki Hiroshi , Sato Yosichika , Ueshima Takayuki
Published: June 2008

The squeeze film damper bearings have been successfully applied for important rotating machinery such as aero engine, high pressure centrifugal compressors[1] and steam turbine[2]. This paper proposes the expansion of application of the damper bearing for small and medium sized rotating machinery. The new damper has a compact size that enable standard design combined with rolling element bearing. A new design of the damper is presented. The new design consists of thin ring and special patterned wire cut grooves. The design analysis and experimental study are presented. The dynamic tests were carried out for this model damper, one is no side seal and the other is with side seals in both ends. Test results showed the sufficient damping effect for actual applications.
The Comparison of Muscle Forces Derived From Different Muscle Models
Authors: Vilimek Miloslav
Published: June 2008

This study, investigated the accuracy, practicality, and sensitivity of several different methods of calculating muscle forces during functional activities in humans. The upper extremity dynamic system was chosen, where the movement flexion / extension elbow joint was studied. The redundant mechanisms were solved using optimization criteria with and without models of individual muscles according to their active and passive properties. Exploration of the control problem for the redundant elbow system was performed using muscle models with and without tendon and activation dynamics. Comparisons with known movements solved by inverse dynamics approach and optimization techniques, provided similar results across to all optimization criteria. Moreover, if muscle models with active and passive properties are included in these analyses, it is relatively easy to calculate muscle forces of both agonists and antagonists. These approaches may be used to provide input data for dynamic FEM stress analysis of bones and bone-implant systems.
Dynamics of a Two-DOF Parallel Pointing Mechanism
Authors: Cammarata Alessandro , Sinatra Rosario
Published: June 2008

This paper presents kinematic and dynamic analyses of a two-degree-of-freedom pointing parallel mechanism. The mechanism consists of a moving platform, connected to a fixed platform by two legs of type PUS (prismatic-universal-spherical). At first a simplified kinematic model of the pointing mechanism is introduced. Based on this proposed model, the dynamics equations of the system using the Natural Orthogonal Complement method are developed. Numerical examples of the inverse dynamics results are presented by numerical simulation.
Dynamic Effects in Stress Analysis for Discrete Elements Modeling: Application to Masonry
Authors: Bohatier Claude , Chetouane Brahim , Vinches Marc
Published: June 2008

The discrete element modelling allows the study of the mechanical behaviour of a collection of solids, submitted to dynamic excitations. The proposed definition of a stress tensor concerns a cell constituted of its kernel, and its neighbouring solids. We demonstrate that taking into account the inertial effects allows the symmetry of the stress tensor. The relative weight of the centrifugal effects remaining in the final expression of the stress tensor is evaluated in order to determine whether or not it has to be taken into account, depending on the application. The proposed definition allows the definition of the load level on different parts of the discontinuous structure. Applications to real masonry cases are presented.
Model Updating Using a Quadratic Form
Authors: Tarazaga Pablo A. , Halevi Yoram , Inman Daniel J.
Published: June 2008

The paper presents a method for model updating, called Quadratic Compression Method (QCM). The updated model has a fixed structure with some free parameters. Algebraic manipulations of the eigenvalue equation lead to a simplified equation with a lower dimension. This equation is then solved in a Least Squares sense. The method is shown to belong to the class of Minimization of the Error in the Characteristic Equation (MECE), with a particular choice of the weighting matrix. The paper presents also a weighted version of the method, called WQCM, which is motivated by reducing the effect of measuring noise. In addition to the theoretic analysis, the superior robustness to noise properties of QCM and WQCM are demonstrated by simulations and experimentally.
The Effect of Bearing Properties on the Eigenvalues of a Rotordynamic System
Authors: Ginsberg Jerry H. , Wagner Benjamin B.
Published: June 2008

This work examines how the natural frequencies and modal damping ratios of a shaft/rotor system are affected by changes in lubricant viscosity and bearing clearance. The analysis considers a uniform elastic shaft with a single rigid rotor mounted away from mid-span, and supported by fully cavitated, π-film, short-length, plain journal bearings. The transverse displacements and cross-sectional rotations are described by Ritz series, and standard fluid film lubrication theory is used to describe the forces generated by the bearings. The clearance and lubricant viscosity are independently adjustable at each bearing. A Campbell diagram, which depicts the imaginary part of the systems eigenvalues as a function of rotation rate, is used to identify critical speeds for the nominal system. With the rotation rate held fixed at a critical value, lubricant viscosity and bearing clearance are allowed to vary, and the fluctuations of natural frequency and modal damping ratio are evaluated.
Metrics for Degree-of-Openness of Engineering Information: Recognizing the Value of Standards-Based PLM — Part 2
Authors: Kim Injoong , Bajaj Manas , Udoyen Nsikan , Mocko Greg , Peak Russell , Wilson Miyako
Published: June 2008

Over a product lifecycle, many engineering tools are used to create computer-based models that need to interact. This poses interoperability problems because of the conflicting formats of the models and differing scopes of the tools. One proposed solution is an open standards-based product lifecycle management (PLM) framework. However, the use of open standards is hindered by the lack of knowledge regarding their actual and potential usage in current engineering processes. To overcome this hurdle and evaluate the opportunities and extent to which open standards can be used in such PLM frameworks, we develop three metrics for degree-of-openness of engineering information: compatibility, coverage, and completeness. To demonstrate the usefulness of the proposed metrics, we assess circuit board design information that is transferred between native models of an electronic CAD system and the STEP AP210 standard (ISO 10303-210). This preliminary experience shows that each of the three useful metrics provides a limited aspect of degree-of-openness, and the combination of these metrics provides a single more holistic degree-of-openness indicator.
Optimal Control of Random Vibration in Shell Structures With Embedded Piezoelectric Components
Authors: To Cho W. S. , Chen Tao
Published: June 2008

The state covariance assignment (SCA) method of Skelton and associates is applied in the present investigation to the optimal random vibration control of large scale complicated shell structures with embedded piezoelectric components. It provides a direct approach for achieving performance goals stated in terms of the root-mean-square (RMS) values which are common in many engineering system designs. The large scale shell structures embedded with piezoelectric components of complicated geometrical configurations are approximated by the hybrid strain or mixed formulation based lower order triangular shell finite element developed in the present investigation. This shell finite element has three nodes every one of which has seven degrees of freedom (dof). The latter include three translational dof, three rotational dof, and one electric potential dof. The element is a better alternative to those based on the displacement formulation and that hinged on the truly hybrid strain formulation. Representative results applying the SCA method for a shell panel embedded with piezoelectric components are included to demonstrate its simplicity of use and efficiency of implementing the proposed approach.
Analyzing Module Commonality for Platform Design in Functional and Physical Domain
Authors: Ho¨ltta¨-Otto Katja
Published: June 2008

Product platforms can provide many advantages from cost savings to a large variety of products with less effort than without platforms. The key choice in modular platform design is the choice of common platform modules. We developed an algorithm to aid in this choice. The algorithm is based on calculating the distance between function inputs and outputs, in the functional domain, or component attributes, in the physical domain. Unlike other methods before, this method can identify commonalities from any or mixed degrees of decomposition and it is not limited to a single measure of commonality. In addition we analyze the degree of commonality quantitatively. The common module candidates are clustered to a hierarchical dendrogram that serves as a decision tool for the designer. It is shown how the algorithm identifies common module candidates for a family of sensors in the functional domain and for a family of micro machines in the physical domain.
The Use of Artificial Intelligence in the Modelling and Heat Treatment Parameters Identification for Alloy-Steel Re-Heating Process
Authors: Chong Zyh Siong , Wilcox Steven , Ward John
Published: June 2008

This paper describes the work undertaken by the University of Glamorgan and CORUS Rotherham UK to apply artificial neural networks to model the cold alloy-steel bars and the heat treatment parameters with their end-product quality characteristics. Standard multi-layered feed forward artificial neural networks (ANNs) were employed to represent the functional mapping of inputs such as physical dimension, material composition and the parameters of the heat treatment cycles to the Brinell Hardness (HB) and the Ultimate Tensile Strength (UTS). The HB and UTS networks were validated with new data sets and demonstrated a satisfactory level of predictions over a range of conditions. These neural networks were then integrated into a Genetic Algorithm (GA) search strategy to identify the best material characteristics and furnace operating parameters in order that both the HB and UTS values are maximised. The results demonstrated that the hybrid strategy of combining the neural network based models with GA can deliver sensible results.
Comparison of Passive and Active Energy Pumping in Mechanical Nonlinear System
Authors: Musienko Andrey I. , Manevitch Leonid I.
Published: June 2008

We describe nonlinear dynamics of essentially non-homogeneous system of coupled oscillators using the technique of multi-scale expansions. The resonant mechanism of passive energy transfer from a massive oscillator into a light auxiliary one provides essential reduction of energy of the massive oscillator. Proposed active control algorithm increases noticeably the efficiency of energy transfer in comparison with passive control. The important advantage of this algorithm is that it provides a small consumption of energy. It is expedient to use our algorithm in the certain limits of parameters determined in the paper. This algorithm provides a necessary level of reduction of oscillator amplitude in a wide range of external perturbations.
Handling Multiple Objectives in Decentralized Design
Authors: Chanron Vincent , Lewis Kemper , Murase Yayoi , Izui Kazuhiro , Nishiwaki Shinji , Yoshimura Masataka
Published: June 2008

Most complex systems, including engineering systems such as cars, airplanes, and satellites, are the results of the interactions of many distinct entities working on different parts of the design. Decentralized systems constitute a special class of design under distributed environments. They are characterized as large and complex systems divided into several smaller entities that have autonomy in local optimization and decision-making. A primary issue in decentralized design processes is to ensure that the designers that are involved in the process converge to a single design solution that is optimal and meets the design requirements, while being acceptable to all the participants. This is made difficult by the strong interdependencies between the designers, which are usually characteristic of such systems. This paper proposes a critical review of standard techniques to modeling and solving decentralized design problems, and shows mathematically the challenges created by having multiobjective subsystems. A method based on set-based design is then proposed to alleviate some of these challenging issues. An illustration of its applicability is given in the form of the design of a space satellite.
Manufacturing Investment and Allocation in Product Line Design Decision-Making
Authors: Michalek Jeremy J. , Ceryan Oben , Papalambros Panos Y. , Koren Yoram
Published: June 2008

An important aspect of product development is design for manufacturability (DFM) analysis that aims to incorporate manufacturing requirements into early product decision-making. Existing methods in DFM seldom quantify explicitly the tradeoffs between revenues and costs generated by making design choices that may be desirable in the market but costly to manufacture. This paper builds upon previous work coordinating models for engineering design and marketing product line decision-making by incorporating quantitative models of manufacturing investment and production allocation. The result is a methodology that considers engineering design decisions quantitatively in the context of manufacturing and market consequences in order to resolve tradeoffs, not only among performance objectives, but also between market preferences and manufacturing cost.
Fractional Control of a Single-Link Flexible Manipulator
Authors: Feliu Vicente , Vinagre Blas M. , Monje Concepcio´n A.
Published: June 2008

A new method to control single-link lightweight flexible manipulators in the presence of changes in the load is proposed in this paper. The overall control scheme consists of three nested control loops. Once the friction and other nonlinear effects have been compensated, the inner loop is designed to give a fast motor response. The middle loop decouples the dynamics of the system, and reduces its transfer function to a double integrator. A fractional-derivative controller is used to shape the outer loop into the form of a fractional-order integrator. The result is a constant-phase system with, in the time domain, step responses exhibiting constant overshoot, independently of variations in the load. Continuous and discrete approximate implementations of the fractional controller are simulated. Comparison of the responses to a step command of the manipulator controlled with the proposed approximations and with the ideal fractional controller showed that the latter could be accurately approximated by standard continuous and discrete controllers of high order preserving the robustness. An interesting feature of this control scheme is that the overshoot is independent of the tip mass. This allows a constant safety zone to be delimited for any given placement task of the arm, independently of the load being carried, thereby making it easier to plan collision avoidance. Simulations also include comparison with standard PD controller, and verification of the assumption of dominant low-frequency vibration mode.
Dynamic Modeling and Performance Evaluation of a Vibrating Cantilever Beam Microgyroscope
Authors: Esmaeili Mehdi , Durali Mohammad , Jalili Nader
Published: June 2008

This paper discusses the effects of substrate motions on the performance of microgyroscopes modeled as suspended beams with a tip mass. The substrate movements can be motions along as well as rotations around the three axes. Using Extended Hamiltonian Principle and Galerkin approximation, the equations of the motion of the beam are analytically derived. In these equations, the effects of beam distributed mass, tip mass, angular accelerations, centripetal and coriolis accelerations are clearly apparent. The effect of electrostatic forces inducing the excitation vibrations are considered as linear functions of beam displacement. The response of the system to different inputs is studied and the system sensitivity to input parameter changes are examined. Finally, the sources of error in the measurement of rotation rate input are recognized. The study demonstrated the importance of errors caused by cross axes inputs on the gyroscope output measurements and overall performance.
An Evaluation of Stability Indices Using Sensitivity Functions for Active Magnetic Bearing Supported High-Speed Rotor
Authors: Takahashi Naohiko , Fujiwara Hiroyuki , Ito Makoto , Fukushima Yasuo , Matsushita Osami
Published: June 2008

Active magnetic bearing (AMB) systems are intrinsically unstable but stabilized by feedback control. In order to evaluate objectively the stability, a standard criterion is necessary. One of the indices for stability evaluation is a maximum gain of sensitivity functions. Radial positions of the rotor are regulated by four-axis control, that is, a radial system needs to be treated as a multi-input multi-output (MIMO) system. One of general criteria for evaluating the stability of a MIMO system is a maximum singular value of a sensitivity function matrix, which needs 16 matrix elements for calculation. It is, however, easier to regard each control axis as an independent single-input single-output (SISO) system and it can be evaluated by just four sensitivity functions. ISO/DIS 14839-3 will employ this concept. This paper discusses the stability evaluation as a SISO system with parallel/conical mode separation or side-by-side treatment, and a MIMO system using maximum singular value, also these differences. In addition to this, a conversion from the usual x,y-axis form to forward/backward form is proposed and the stability is evaluated for the system in the converted form. For experimental evaluation, a test rig diverted from a high-speed turbo compressor rated at 180kW was used. The transfer functions were measured by exciting the system with swept signals at rotor standstill and at 30,000r/min rotational speed. For stability limit evaluation, the control loop gain was increased or a phase lag was inserted in the control loop to lead the system to be nearby unstable intentionally. Using these test results, the differences among the evaluation manners are discussed.
A Service-Oriented Approach to Engineering Ontology Development for Product Lifecycle Processes
Authors: Yang Q. Z. , Miao C. Y.
Published: June 2008

This paper presents a service-oriented methodology for ontology modeling and engineering to support the semantics-based integration of manufacturing systems and processes. The proposed methodology is based on the OWL-S semantic service description framework. It specifies a service-oriented ontological engineering process and a set of methods and techniques to address the issues of semantic description of the virtualized services, standardization, ontology repository, as well as the support for automatic service discovery, composition and interoperation of the ontology-driven software applications. The approach has been used for ontology modeling of product lifecycle processes, such as for developing ontologies of quality assurance processes in the product design. By illustrating the construction of an application service ontology for the design quality process management, this paper shows how the service-oriented approach is used to capture the semantic concepts in the domain. It further describes how the captured semantics are used for OWL-S based service discovery and composition in design quality process management.
Bifurcation Analysis of a Non-Radial Tethered System
Authors: Valverde J. , Escalona J. L. , Domi´nguez J. , Champneys A. R.
Published: June 2008

The Short Elecytrodynamic tether is a space structure that comprises a thin, long beam that is spun in a horizontal configuration from a satellite in low Earth orbit, with a massive electrically conducting disk at its free end. A geometrically exact bifurcation analysis is performed using a Cosserat formulation which leads to a system of Kirchhoff equations for the beam’s shape as a function of position and time. Moving to a rotating frame, incorporating the effects of internal damping, intrinsic curvature due to the deployment method and novel force and moment boundary conditions at the contractor, the problem for steady rotating solutions is formulated as a two-point boundary value problem. A bifurcation analysis is carried out using numerical continuation methods varying rotation speeds up to many times the critical resonance frequency.
Nonlinear Analysis of a Self-Excited Cantilever Beam
Authors: Kaneko Hiroyuki , Yabuno Hiroshi , Kuroda Masaharu
Published: June 2008

In this study, we investigate the dynamics of a self-excited cantilever beam by a positive feedback proportional to the velocity. In particular, we focus on the response amplitude in the self-excited oscillation and analyze the effect of the nonlinear component of the restoring force in the cantilever. It is theoretically and experimentally clarified that the response amplitude grows with time under the positive feedback proportional to the velocity (positive feedback). Furthermore, van der Pol type self-excited cantilever beam is designed by applying the nonlinear feedback proportional to the squared deflection and the velocity, and the steady state response is realized in the cantilever beam. The theoretically predicted effects of the nonlinear feedback are qualitatively confirmed by performing some experiments.
Feasibility Assessment in Preliminary Design Using Pareto Sets
Authors: Gurnani Ashwin , Ferguson Scott , Donndelinger Joseph , Lewis Kemper
Published: June 2008

In this paper, we present the development and application of a Technical Feasibility Model (TFM) used in preliminary design to determine whether or not a set of desired product specifications is technically feasible, and the optimality of those specifications with respect to the Pareto frontier. The TFM is developed by integrating the capabilities of a multidisciplinary design framework, a multi-objective design optimization tool, a Pareto set gap analyzer, metamodeling methods, and mathematical methods for feasibility assessment. This tool is then applied to a three objective example problem and to a five objective passenger vehicle design problem by analyzing benchmarking data from 78 late model sedans.
Flow Induced Vibration of an Axisymmetric Flow Between Two Parallel Disks
Authors: Warner Grant , Nayeb-Hashemi Hamid , Olia M.
Published: June 2008

A system of parallel disks may be cooled by passing a fluid between these disks. Depending on the disk geometries, their distance, mechanical properties and fluid velocity, the disks may be subjected to transverse vibration which may be damped or become unstable. There are number of papers on the flow induced vibration in pipes with various boundary conditions addressing their transverse vibration characteristics. However, there is very little information on the vibration characteristics of disks with axisymmetric fluid flow in between. The equation of motion of two parallel disks with an axisymmetric flow in between is developed using Hamiltonian principle. In the initial phase of this study, it was assumed that two plates move in the same direction, thus maintaining their initial gap. The governing equations are non-dimensionalized and the effects of plates moment of inertia, density, geometry and fluid velocity on the dynamic response of the plates are obtained.
Vibration Localization in Near-Periodic Coupled Two-Dimensional Resonator Arrays
Authors: Judge John A. , Vignola Joseph F. , Houston Brian H. , Photiadis Douglas M. , Marcus Martin H.
Published: June 2008

The effects of small deviations from periodicity on the vibration behavior of coupled arrays of mechanical resonators are investigated, and the consequences for energy propagation across such arrays are described. Existing localization theory is applied to demonstrate that one-dimensional arrays designed as bandpass filters are particularly sensitive to aperiodicity when narrow passband requirements dictate weak inter-resonator coupling. A novel two-dimensional array of resonators is proposed that is less sensitive to disorder than one-dimensional arrays, improving filter performance without the need for improved manufacturing tolerances. Numerical simulations of a simple model are employed to demonstrate the effects of disorder on one- and two-dimensional arrays, and a case study design is discussed that includes statistical investigation using finite-element analysis and experimental measurements of a prototype two-dimensional array.
Using a Virtual Dummy to Simulate Vibration Dose Value for Different Car Occupants
Authors: Pennestri` E. , Stefanelli R. , Valentini P. P. , Vita L.
Published: June 2008

The comfort assessment for car occupants is not an easy task to achieve. It is a matter of personal perceiving, thus a solution which may seem comfortable to one could be not to another. Moreover it is a field which requires knowledge both from science and medicine. The vibrational comfort analysis is the topic of this paper. There are different international standards to define the vibrational comfort through computed indices. In particular the British Standard BS 6841 [1] introduces the Vibration Dose Value (VDV). The main idea which lies behind the VDV is to estimate the whole body vibration. In fact the standard suggests the main locations for acceleration measurement (feet, seat and back) and their direction axes. The overall number of acquisitions is twelve. A numerical code for the vibrational comfort analysis of car occupants, estimating the VDV for each of them, has been developed. The code, named DAViD, is based on a multibody approach [2]. It has been validated by means of experimental tests [3,4]. In this paper the influence of the anthropometric features (height and weight) and the inclination of the backrest on the VDV has been investigated. The code is an useful tool for predicting at the seat design level the vibrational discomfort.
Modelling of Hydrodynamic Journal Bearing in Spatial Multibody Systems
Authors: Stefanelli R. , Valentini P. P. , Vita L.
Published: June 2008

The model of a three dimensional journal bearing with hydrodynamic lubrication is herein presented. This model is suitable for embodiment into the equations of spatial multibody systems. Both rotational and squeeze effects together with tilting effect have been taken into account. Moreover a simplified model of friction has been also reported. The proposed methodology has been applied to an example concerning an unbalanced rotor supported by two journal bearings.
A Fractional Calculus Perspective in Electromagnetics
Authors: Machado J. A. Tenreiro , Jesus Isabel S. , Galhano Alexandra
Published: June 2008

Some experimentation with magnets was beginning in the late 19th century. By then reliable batteries had been developed and the electric current was recognized as a stream of charge particles. Maxwell developed a set of equations expressing the basic laws of electricity and magnetism, and demonstrated that these two phenomena are complementary aspects of electromagnetism. He showed that electric and magnetic fields travel through space, in the form of waves, at a constant velocity. Maxwell is generally regarded as the nineteenth century scientist who had the greatest influence on twentieth century physics, making contributions to the fundamental models of nature. Bearing these ideas in mind, in this study we apply the concept of fractional calculus and some aspects of electromagnetism, to the static electric potential, and we develop a new fractional order approximation method to the electrical potential.