bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Approach for Changing Structural Properties of a Membrane Mirror Strip for Adaptive Optics Applications
Authors: Renno Jamil M. , Tarazaga Pablo A. , Grisso Benjamin L. , Inman Daniel J.
Published: May 2009

This work investigates improving the imaging quality of membrane mirrors using multiple active fiber composite (AFC) actuators. It is demonstrated in the literature that the structural characteristics of a circular membrane lens can be used advantageously to eliminate nearly 100% of a 5th order image aberration. The approach here is to study the transverse vibration of a membrane mirror strip augmented with two micro fiber composite (MFC) bimorphs. Each bimorph is placed near one of the ends of the strip. One of the bimorphs will be excited in phase, causing a local tension in the strip, whereas the other will be excited out of phase, causing a local bending moment. The finite element method (FEM) is used to present the system mathematically. The advantage of the FEM is evident; it easily handles the physical non-uniformities caused by the augmentation of the actuators. To verify the presented model, a constant in-phase voltage is supplied to one of the MFCs. Hence, the local tension induced by this MFC bimorph is constant, and the resulting model is linear. A frequency response is obtained from the FEM model and through an experiment. The FEM and experimental results are in agreement. Additionally, results show that the local tension changes the structural properties of the membrane strip. The proposed approach can be extended to the two dimensional case with the promise of contributing to the elimination of image aberrations.
Simplified Formula for Determining the Width of the Gear Wheels of Face Gears Using Design of Experiments
Authors: Guingand Miche`le , Remond Didier , de Vaujany Jean-Pierre
Published: May 2009

This paper deals with face gear design. The goal is to propose a simple formula for predicting the width of the wheel as a function of the main design parameters. Specific software was used to achieve this goal. This numerical tool is able to simulate the geometry and the quasi-static loaded behavior of a face gear. The statistical method used for analyzing the influence of data is described: the Design Of Experiment (DOE) leads to a simple regression model taking into account the influential parameters and their couplings. In the last part, the results of the formulae are compared to those of the software and an optimal design is proposed based on the regression.
Transmission Error and Noise Emission of Spur Gears: A Theoretical and Experimental Approach
Authors: Davoli Piermaria , Gorla Carlo , Rosa Francesco , Rossi Fabrizio , Boni Giuseppe
Published: May 2009

Noise reduction is becoming a more and more important target for industrial gearboxes. The achievement of this goal requires a precise identification of gear noise sources, because only a good understanding of the phenomena involved in gear noise can give to the designer the tools to conceive gears with reduced acoustic emission, avoiding the time consuming and expensive “trial and error” procedure [1]. The variable component of Transmission Error (TE) is commonly recognized as one of the most important sources of gear noise. TE is mainly caused by teeth deflections under load and by manufacturing and assembly errors. The usual approach to these problems is to conceive profile modifications and crowning that absorb deformations and errors, in order to reduce TE and consequently noise. Since the correlation between gear TE and noise is complicated, profile modifications are often designed on the basis of past field experience, while software tools to predict TE as a function of tooth modifications are of great help. Nevertheless, such software tools must be validated through experimental tests. A software based on a simplified model of gear meshing, that takes into account manufacturing errors and profile modifications, has been developed and validated by means of a new test rig, specifically conceived for TE, vibrations and noise emission measurements. The rig has been designed and installed in the Laboratories of the Department of Mechanical Engineering, Politecnico di Milano. In this paper software simulations, TE predictions, TE and acoustic measurements are described and discussed. TE has been predicted and measured for two different gear sets, with the same macro-geometry (module, teeth number, center distance) and different micro-geometry (profile modifications); acoustic emission has also been measured. TE measurements show a good agreement with the theoretical predictions. The measurements made with the new test rig confirm the close correlation between TE and the level of acoustic emission.
Loaded TCA of Measured Tooth Flanks for Lapped Hypoid Gears
Authors: Saiki Kohei , Tobisawa Keiichiro , Kano Masaki , Ohnishi Yasuharu , Kusaka Takashi
Published: May 2009

Usually, the Loaded Tooth Contact Analysis (i.e. LTCA) of hypoid gears uses the nominal tooth flanks described by the machine setting and the cutter specifications. Only a few studies are performed on the LTCA directly using the measured tooth flanks such as carbonize-hardened and lapped hypoid gears. This paper presents an innovative LTCA method directly using the measured tooth flanks at each manufacturing step including not only the milling or hobbing process but also the troublesome heat-treatment, lapping or grinding processes. The proposed new LTCA method is extremely concise. Firstly, the 3-D shape data of the manufactured tooth flanks, which are the original x-y-z coordinates but not the differences against their nominal tooth flanks as before, are obtained on a coordinate-measuring machine. Another important factors the load deflections are measured on the assembled transmission by applying the static transmitting torque. Secondly, the pinion and gear are localized at the nominal mounting position, and the no load TCA can be obtained by calculating the gap between the original tooth flanks at each roll angle. Lastly, since the load deflections can be considered as the movement of mounting position, the Loaded TCA can be obtained by calculating the gap between the moved tooth flanks at new mounting position. As practical applications, the new LTCA method is used to improve the strength of high-torque hypoid gears for an All-Wheel-Drive transmission. As a result, the tooth contact pattern and pitting position observed in endurance test agreed well to the LTCA predictions and the demanding life is achieved by modifying the loaded contact pattern of lapped hypoid gears.
Form Grinding of Precision Helical Rotors and Gears Using Closed-Loop Profile Control
Authors: Holmes C. S.
Published: May 2009

Starting with a description of a system for precision profile grinding of screw compressor rotors using closed-loop feedback for correction of profile errors, the paper goes on to describe a new system for the form grinding of precision spur, helical, and worm gears. This paper describes the development of high precision helical form grinding systems. The system was originally developed to satisfy the demanding accuracy requirements of screw compressor rotors, which will be understood from a description of their function. The system was then developed for the grinding of helical and spur gears to Quality 2/3 of DIN 3962. The paper describes both systems, with reasons for the design choices, and the results obtained. It is intended to be of interest to designers and manufacturers of rotors and gears.
Traction Drive CVT Technologies for Aircraft Equipment
Authors: Goi Tatsuhiko , Tanaka Hirohisa
Published: May 2009

In 1996, research activities on traction drive CVT technologies was commenced in order to apply them to aircraft equipment. Extensive efforts have been conducted to overcome various technical barriers such as weight and severe environmental conditions with employing high speed traction drive technology, a split power mechanism and a sensorless control method using “Observer”. Using these technologies, a all new concept IDG called “T-IDG®” has been developed.
Voice and Ultrasonic Sensors to Control Autonomous Robots
Authors: Fezari Mohamed , Bousbia-Salah Mounir
Published: May 2009

In this paper, a voice command system for autonomous robots is proposed as a project. The methodology adopted is based on hybrid techniques used in speech recognition which are zero crossing and extremes with dynamic time warping followed by a decision system based on independent methods test results. To implement the approach on a real time application, a Personal Computer interface was designed to control the movement of a set of robots by voice commands. The voice command system for four autonomous robots is designed. The main parts of the robots are a microcontroller from Microchip PIC16F876, a set of ultrasonic modules and a radio frequency receiver module.
Development of Validation Metrics for Vehicle Frontal Impact Simulation
Authors: Yang R. J. , Li G. , Fu Y.
Published: May 2009

This research addresses the development of validation metrics for vehicle frontal impact simulation. The model validation metrics provide a quantified measurement of the difference between CAE simulation and physical test. They are useful to develop an objective model evaluation procedure for eventually achieving the goal of zero or near zero prototyping. In this research, full frontal crash pulses are chosen as the key items to be compared in the vehicle frontal impact simulation. Both physics- and mathematics-based metrics are investigated. The physics-based metric include a method of using a simplified step function representation and the mathematics-based metrics include methods of wavelet decomposition, corridor violation plus area, and metrics used in a commercial code ADVISER, respectively. They are all correlated to subject matter experts’ rating through optimal weightings. A new metric, considering variabilities from both experts and metrics for frontal crash pulse, is proposed. One example is used to demonstrate its application.
Transverse Vibration Instabilities in Multiribbed Belt Transmission Subjected to Multi-Frequency Excitations: Modelling and Experiments
Authors: Michon Guilhem , Manin Lionel , Remond Didier , Dufour Regis , Parker Robert G.
Published: May 2009

This paper experimentally investigates the parametric instability of an industrial axially moving belt subjected to multifrequency excitation. Based on the equations of motion, an analytical perturbation analysis is achieved to identify instabilities. The second part deals with an experimental set-up that subjects a moving belt to multi-frequency parametric excitation. A data acquisition technique using optical encoders and based on the angular sampling method is used with success for the first time on a non-synchronous belt transmission. Transmission error between pulleys, pulley/belt slip and tension fluctuation are deduced from pulley rotation angle measurements. Experimental results validate the theoretical analysis. Of particular note is that the instability regions are shifted to lower frequencies than the classical ones due to the multi-frequency excitation.
Flexural Vibration Band Gaps in Periodic Sandwich Beams With Auxetic Core
Authors: Wen Jihong , Wen Xisen , Yu Dianlong
Published: May 2009

The flexural vibration band gaps in one-dimensional periodic sandwich beams with auxetic core are studied basing on the theory of Phononic crystals. The band structures of one-dimensional periodic sandwich beams with auxetic core are presented with the plane wave expansion method, the regular calculation method in phononic crystals. Further, the effects of material parameters and structure parameters on the gaps are analyzed. The vibration band gaps in the sandwich beams provide a new idea for the vibration controlling of the structure.
Hydrogen Addition Effects on Swirl Stabilized Methane Flame
Authors: Kim H. S. , Arghode V. K. , Gupta A. K.
Published: May 2009

Effect of hydrogen addition in methane-air premixed flames has been examined from a swirl stabilized combustor under confined flame conditions. Different swirlers have been examined to investigate the effect of swirl intensity on enriching methane-air flame with hydrogen in a laboratory-scale pre-mixed combustor operated at 5.81 kW. The flame stability was examined at same head load (5.81 kW) for various parameters such as amount of hydrogen addition, combustion air flow rates and swirl strengths. This was done by comparing adiabatic flame temperatures at the lean flame limit. The combustion characteristics of hydrogen enriched methane flames at constant heat load but different swirl strength were examined using particle image velocimetry (PIV), OH chemiluminescence, micro-thermocouples diagnostics to provide information on velocity and temperature field, and combustion generated OH concentration in the flame. Gas analyzer was used to obtain NOx and CO concentration at the exit. The results show that the the lean stability limit is mostly extended by hydrogen addition, but it can reduce in case of higher swirl intensity operating at lower adiabatic flame temperatures. The addition of hydrogen increases the NOx emission; however, this effect can be reduced by increasing either the excess air or swirl intensity. The results of NOx and CO emissions were also compared with a diffusion flame type combustor. The NOx emissions of hydrogen enriched methane premixed flame was found to be lower than the corresponding diffusion flame under the fuel lean condition.
Distributed Friction Damping of Traveling Wave Vibration in Rods
Authors: Tangpong X. W. , Wickert J. A. , Akay A.
Published: May 2009

A ring damper can be affixed to a rotating base structure such as a gear, an automotive brake rotor, or a gas turbine’s labyrinth air seal. Depending on the frequency range, wavenumber, and level of preload, vibration of the base structure can be effectively and passively attenuated by friction that develops along the interface between it and the damper. The assembly is modeled as two rods that couple in longitudinal vibration through spatially-distributed hysteretic friction, with each rod having periodic boundary conditions in a manner analogous to an unwrapped ring and disk. As is representative of rotating machinery applications, the system is driven by a traveling wave disturbance, and for that form of excitation, the base structure’s and the damper’s responses are determined without the need for computationally-intensive simulation. The damper’s performance can be optimized with respect to normal preload, and its effectiveness is insensitive to variations in preload or the excitation’s magnitude when its natural frequency is substantially lower than the base structure’s in the absence of contact.
Nonlinear Dynamic Behavior of Turbocharger Rotor-Bearing Systems With Hydrodynamic Oil Film and Squeeze Film Damper in Series: Prediction and Experiment
Authors: Gjika Kostandin , Groves Chris , San Andre´s Luis , LaRue Gerald D.
Published: May 2009

Current trends for advanced automotive engines focusing on downsizing, better fuel efficiency and lower emissions have led to several changes in turbocharger bearing systems design and technology. Automotive turbochargers run faster and use engine oils with very low viscosity under high oil inlet temperature and low feed pressure. The development of high performing bearing systems, marrying innovation with reliability, is a persistent challenge. This paper shows progress on the nonlinear dynamic behavior modeling of rotor-radial bearing system (RBS) incorporating two oil films in series: a hydrodynamic one with a squeeze film damper commonly used in turbochargers. The developed fluid bearing code predicts bearing rotational speed (in case of fully floating design), operating inner and outer bearing film clearances, effective oil viscosity taking into account its shear effect, and hydrostatic load. A rotordynamics code uses this input to predict the nonlinear lateral dynamic response of the rotor-bearing system. The model predictions are validated with test data acquired on a high speed turbocharger RBS of 6.0 mm journal diameter running up to 250,000 rpm (maximum speed), 5W30 oil type, 150 °C oil inlet temperature, and 4 bar oil feed pressure. The tests are conducted at a rotordynamics technology laboratory using a high performance data acquisition system. Turbochargers with four combinations of inner and outer RBS clearances are tested. Prediction and measured synchronous response and total motion are in good agreement. Both demonstrate the nonlinear character of RBS behavior including several subsynchronous frequencies components across the operating speed range. The non linear predictive model aids the development of high performance and optimized turbocharger RBS with faster development cycle times and increased reliability.
Development of a Technique Preparation Integration System With Agent Technology
Authors: Liu Xinhua , Wang Weida , Liu Wenjian , Xing Yue
Published: May 2009

This study intends to propose an intelligent system with agent technology in order to realize integration and cooperation of technique preparation process. The agent-based system framework, in which various intelligent agents worked together to perform technique preparation tasks in an autonomous and collaborative way, is put forward. The system consists of three categories of agents and functional definition of each intelligent agent is presented. Moreover, agents communication mechanism and cooperation sequence diagram are proposed. Finally, an intelligent algorithm based on fuzzy comprehensive evaluation is designed to resolve competition conflicts among the agents.
Loop-Structure Decomposition of Kinematic Chains, Application to Rigid Sub-Chain Detection
Authors: Ding Huafeng , Huang Zhen
Published: May 2009

Rigid sub-chain detection and isomorphism identification are two of the most difficult problems in the computer aided structure synthesis of kinematic chains. Based on the array representation of the loops of kinematic chains, this paper first introduces two operations of loops. Then a new theory of structure decomposition of kinematic chains is proposed on the basis of the concept of the independent loop set. After that a new method grounded on the theory is proposed for rigid sub-chain detection. Finally, the optimized algorithm for structure decomposition is presented and the corresponding program for rigid sub-chain detection is developed as well.
Multi Process Routes Decision-Making Through Integration of Workflow Technology and Max-Min Ant System
Authors: Liu Wenjian , Liu Xinhua , Jin Tianguo
Published: May 2009

In order to realize visualization and intelligence of computer-aided process planning, this paper proposes an intelligent system with the integration of workflow technology and max-min ant system. Workflow modeling technology was applied to represent multi-process routes decision-making problem (MRDP) and a heuristic algorithm based on expert knowledge was designed to construct the directed graph for MRDP. Moreover, a modified ant colony algorithm was proposed to exploit the best solution using improved max-min pheromone strategy and the way of updating pheromone. Finally, an experiment example is illustrated to demonstrate the proposed methodology.
CAD-Based Automatic Generation of Robot Trajectory in Shoe Spray Systems
Authors: Wu Chuanyu , He Leiying , Hu Xudong , Li Qinchuan
Published: May 2009

Automatic generation of robot trajectory for adhesive spray is highly desirable for shoe manufacturing. However, nowadays robotic trajectories are programmed by teach-in instead of automatic approaches. To cope with it, an approach based on a programming tool will be described. It aims at enabling the automatic generation of robot spray trajectories from different kinds of shoe sole models in three-dimensional CAD files. Trajectory could be generated as an offset curve on the surface patch of shoe sole. A set of operating points in spray trajectory can be calculated by means of linear interpolation. At the same time, their orientations including tangential directions and normal directions are computed. Results show that this approach is highly time-efficient by avoiding tedious teaching processes. This study will increase the automation level of the shoe production as well as its flexibility, and is therefore expected to provide higher productivity.
Augmented Time-Stepping by Step-Size Adjustment and Extrapolation
Authors: Studer Christian , Glocker Christoph
Published: May 2009

Time-stepping schemes are widely used when integrating non-smooth systems. In this paper we discuss an augmented time-stepping scheme which uses step-size adjustment and extrapolation. The time evolution of non-smooth systems can be divided in different smooth parts, which are separated by switching points. We deduce the time-stepping method of Moreau, which is a common order-one integration method for non-smooth systems. We formulate the method using contact inclusions, and show how these inclusions can be solved by a projection. We show how time-steps which contain a switching point can be detected by observing the projection behaviour, and propose a step-size adjustment, which treats these switching time-steps with a minimal step-size Δtmin. Time-steps in smooth parts of the motion are run with a larger step-size, and an extrapolation method, which is based on the time-stepping scheme, is used to increase the integration order. The presented method is suitable for mechanical systems with unilateral and frictional contacts. For simplicity, we deduce the method considering solely mechanical systems with one unilateral contact.
Assuring Molded Accuracy of Plastic Involute Worm Gears
Authors: Weiss Michael T. , Kleiss Roderick E.
Published: May 2009

Many plastic geared transmissions contain crossed-axis worm drives in the first stage. The purpose is usually to achieve high reduction and/or tailored package size. The need for precision control of worm and helical gear geometry is just as important for this gear mesh as for any other. A myriad of molded flaws can degrade or destroy the performance of these gears. Pitch, tooth thickness, and lead errors are only a few possibilities. Barrel shaped, tapered, or hourglass bodies must be identified and controlled. Asymmetrical teeth are a distinct possibility as well. The only proper way to detect and evaluate these conditions is to scan and analyze these gears in three dimensions. The traditional method of scanning only one section of the tooth on a worm and then scanning the lead at the pitch line will not reveal many molded gear error sources. Measuring pitch or tooth thickness by taking single point measurements around the gear will also miss many errors. We have developed scanning and analysis techniques to accurately map the size and accuracy of these truly three-dimensional involute gear shapes.
GA-Based Fuzzy Logic Control for a Smart Fin of a Projectile
Authors: Mudupu Venkat , Trabia Mohamed B. , Yim Woosoon , Weinacht Paul
Published: May 2009

This paper presents the design and testing of a smart fin for a subsonic projectile. The smart fin is activated using a piezoelectric bimorph with a substrate that is completely enclosed within the fin. A linear model of the actuator and fin system is created using the frequency response identification technique within MATLAB System Identification Toolbox. A procedure for designing a GA-based fuzzy logic controller for the fin is presented. Experimental and simulation results show that the proposed controller achieved the fin angle control under different operating conditions.
Effect of Misalignment of Retainer Bearings on Dynamic Responses of Rotor System During Emergency Stop
Authors: Ka¨rkka¨inen Antti Y. J. , Helfert Marlene , Aeschlimann Beat , Mikkola Aki M. , Sopanen Jussi T.
Published: May 2009

The active magnetic bearings present a technology which has many advantages compared to traditional bearing concepts. Active magnetic bearings, however, require retainer bearings in order to prevent damages in the event of a component, power or a control system failure. In the drop-down, when the rotor drops from the magnetic field on the retainer bearings, the design of the retainer bearings has a significant influence on the dynamic behavior of the rotor. In this study, the dynamics of an active magnetic bearing supported rotor during the drop on retainer bearings is studied employing a detailed simulation model. The retainer bearings are modeled using a detailed ball bearing model while the flexibility of the rotor is described using the component mode synthesis. The model is verified by comparing measurements carried out using an existing test rig and simulation results. In this study, the verified simulation model is employed studying the effect of misalignment of retainer bearings during the rotor drop-down on the retainer bearings. It is noted that the misalignment of the retainer bearings is harmful and can produce whirling motion of the rotor.
Problems With the Design of Internal Gearing With Extreme Parameters
Authors: Nemcek Milos
Published: May 2009

Gears with an internal gearing are more exploited today for their indisputable advantages. This contribution deals with some of the rare problems in designing these gears: - internal gearing with a small number difference between teeth, even if this difference is zero; - application of High Contact Ratio (HCR) gearing for an internal gearing; - solution of problems related to restriction given by the root spacewidth of a designed ring gear.
Dynamics Design of a Planar Controllable Five Bar Mechanism Based on Genetic Algorithm
Authors: Zhang Ke
Published: May 2009

A hybrid five bar mechanism is a typical planar parallel robot. It is a configuration that combines the motions of two characteristically different motors by means of a five bar mechanism to produce programmable output. Hybrid five bar mechanism is the most representative one of hybrid mechanism. In this paper, considering the bond graph can provide a compact and versatile representation for kinematics and dynamics of hybrid mechanism, the dynamics analysis for a hybrid five-bar mechanism based on power bond graph theory is introduced. Then an optimization design of hybrid mechanism is performed with reference to dynamic objective function. By the use of the properties of global search of genetic algorithm (GA), an improved GA algorithm is proposed based on real-code. Optimum dimensions are obtained assuming there are no dimensional tolerances or clearances. Finally, a numerical example is carried out, and the simulation result shows that the optimization method is feasible and satisfactory in the design of hybrid mechanism.
Balancing of a Highly Flexible Rotor by Using Artificial Neural Networks
Authors: Villafan˜e Saldarriaga Manuel , Mahfoud Jarir , Steffen Valder , Der Hagopian Johan
Published: May 2009

The present work is an alternative methodology in order to balance an unsymmetrical damped highly flexible rotor by using neural networks. This procedure was developed aiming at improving the performance of classical balancing methods, which are not well adapted to these situations. The approach developed is based on the influence coefficient method and is adequate to integrate an active balancing system. The methodology is tested successfully experimentally.
Axisymmetrical Stress Analysis and Strength of Epoxy-Steel Composite Cylinders Under Push-Off Loadings
Authors: Sawa Toshiyuki , Hasegawa Taro
Published: May 2009

Composite parts have been used widely for lightening and strengthening mechanical parts, and it is necessary to know the contact stress distributions at the interfaces of the composites. In this paper, the interface stress distribution in composite cylinders of epoxy and steel under push-off loadings is analyzed using axisymmetrical theory of elasticity as a three-body contact problem. Analogous test was conducted to determine the relationship between the normal stress and the shear stress. Using two stress singularity parameters obtained from the numerical stress analyses and analogous test results, a method for estimating the strength of the composite cylinders was proposed. In the numerical calculations, the effects of the diameter and Young’s modulus of the solid cylinders on the interface stress distributions are clarified. It is seen that the normal stress and the sheer stress at the lower edges of the interface increase as Young’s modulus of the solid cylinders increases. It is also found seen that the normal stress increases and the sheer stress decreases as the diameter of the solid cylinders increases. The experiments were carried out for measuring the ruptured push-off loadings of the composite cylinders. In the experiments, the effects of the diameter of steel cylinders were examined. It is seen that the push-off strength increases as the diameter of the steel cylinders increases. The numerical results are in fairly good agreements with the experimental results.
Nonlinear Dynamic Response Analysis of Rotor-Ball Bearing-Stator Coupling System Including Unbalance-Rubbing Coupling Faults
Authors: Chen Guo , Hou Rong Tao
Published: May 2009

In this paper, a new rotor-ball bearing-stator coupling system dynamic model is established. In the model, the rotor mass unbalance and rubbing faults are included, and the nonlinear factors of ball bearing such as the clearance of bearing, nonlinear Hertzian contract force between balls and races, and the varying compliance vibration coming from the periodical variety of contact positions between balls and races are modeled. The numerical integral method is employed to obtain system’s responses, and the vibration amplitude-rotating speed curve, bifurcation plot, phase plane plot, shaft centre orbits, frequency spectrum and Poincare´ map are used to carry out the analysis of bifurcation and chaos motion, and the effects of rotational speed, rubbing stiffness, rotor eccentricity, bearing house-stator stiffness, and stator-foundation stiffness on dynamic responses are analyzed, and the non-linear dynamic characteristics of rotor-ball bearing-stator system under unbalance and rubbing coupling faults are discovered.
Suppression of Internal Damping-Induced Instability Using Adaptive Techniques
Authors: Simon Andra´s , Flowers George
Published: May 2009

Advanced rotor systems, for such applications as high-speed flywheel systems, consist (in a basic fashion) of a lightweight rotor spinning at relatively high speeds and supported by magnetic bearings. Composite materials are an extremely attractive choice for such rotor designs, offering high strength with light-weight. However, there are a number of issues that must be addressed for such efforts to be successful. Specific issues include imbalance control and active techniques to suppress internal damping-induced instability. A detailed description of the problem being considered and a strategy for solving it are presented. Simulation modeling and analysis results are presented and discussed to illustrate the method and demonstrate its effectiveness.
Distributed Shape Optimization of Compliant Mechanisms Using Intrinsic Functions
Authors: Lan Chao-Chieh , Cheng Yung-Jen
Published: May 2009

A compliant mechanism transmits motion and force by deformation of its flexible members. It has no relative moving parts and thus involves no wear, lubrication, noise, and backlash. Compliant mechanisms aims to maximize flexibility while maintaining sufficient stiffness so that satisfactory output motion can be achieved. When designing compliant mechanisms, the resulting shapes sometimes lead to rigid-body type linkages where compliance and rotation is lumped at a few flexural pivots. These flexural pivots are prone to stress concentration and thus limit compliant mechanisms to applications that only require small-deflected motion. To overcome this problem, a systematic design method is presented to synthesize the shape of a compliant mechanism so that compliance is distributed more uniformly over the mechanism. With a selected topology and load conditions, this method characterizes the free geometric shape of a compliant segment by its rotation and thickness functions. These two are referred as intrinsic functions and they describe the shape continuously within the segment so there is no abrupt change in geometry. Optimization problems can be conveniently formulated with cusps and intersecting loops naturally circumvented. To facilitate the optimization process, a numerical algorithm based on the generalized shooting method will be presented to solve for the deflected shape. Illustrative examples will demonstrate that through the proposed design method, compliant mechanisms with distributed compliance will lessen stress concentration so they can be more robust and have larger deflected range. It is expected that the method can be applied to design compliant mechanisms that have a wide variety of applications from precision instruments to biomedical devices.
Study of the Influence of the Revolute Joint Model on the Dynamic Behavior of Multibody Mechanical Systems: Modeling and Simulation
Authors: Flores P. , Ambro´sio J. , Claro J. C. P. , Lankarani H. M.
Published: May 2009

The influence of the revolute joint model on the dynamic behavior of multibody systems is investigated throughout this work. In the process, under the framework of the multibody systems formulation, a general methodology for modeling revolute joints with clearance is presented. The numerical models for normal and tangential contact forces are reviewed. The contact-impact forces developed during the contact are evaluated and introduced into the equations of motion of the multibody mechanical system. Moreover, the main kinematic and dynamic aspects of the modeling lubricated revolute joints are presented and discussed in this work in order to compare them with the dry revolute joint. The hydrodynamic forces are obtained by integrating the pressure distribution evaluated with the aid of Reynolds’ equation written for the dynamic regime. The hydrodynamic forces are nonlinear functions of the journal centre position and of its velocity with reference to the bearing center. The hydrodynamic forces built up by the lubricant fluid are evaluated from the state of variable of the system and included into the equations of motion of the mechanical system. The main assumptions and procedures adopted in this work are demonstrated through simulations of a slider-crank mechanism, which includes a revolute joint with clearance.
A Family of Novel Lower-Mobility Decoupled Parallel Mechanisms
Authors: Zeng Daxing , Zhu Sijun , Huang Zhen
Published: May 2009

This paper presents a family of novel lower-mobility decoupled parallel mechanisms (DPMs), which consists of one 5-DOF (degree of freedom) DPM, two 4-DOF DPMs, three 3-DOF DPMs, and three 2-DOF DPMs. The basic feature of this family is that the moving platform and the fixed base of the DPMs are connected by two limbs and the motion of the moving platform is fully decoupled. Then the constraint screw method is used to analyze the motion feature of all DPMs presented in this paper. The mobility of these DPMs has also been calculated by the Modified Grubler-Kutzbach criterion. All the DPMs in this paper are simple and no computation is required for real-time control.
A Service-Oriented Architecture for Interdisciplinary Product Design Workflow Choreography
Authors: Zeng Sai , Singh Man-Mohan , Gomes Jose´ , Boier-Martin Ioana M.
Published: May 2009

Inter-disciplinary collaboration is critical to the success of processes employed in the development of complex products. A Workflow Management System (WMS) formalizes and automates product development process activities at various stages in the product lifecycle. Existing bridges between a WMS and the application systems involved in product development processes focus on intradisciplinary activities and static binding of artifacts to such activities. In this paper, we describe a novel SOA-based approach to bridge the gap between WMS and loosely-integrated domain-specific application systems focused on interdisciplinary process activities and dynamic binding of artifacts to activities. Our approach builds upon service-oriented inter-disciplinary collaboration architecture. Our solution consists of two components: System Data Management (SDM) and a template for integration between a WMS and the SDM. We illustrate our approach using an automotive use case for requirements verification.
Power-Transfer Capacity of a Geared-Neutral Transmission
Authors: Gecim Burak , Anderson Neil , Wehking Jeffrey
Published: May 2009

Geared-neutral Continuously Variable Transmission (CVT) designs offer various kinematic advantages including a wide ratio range, and elimination of starting devices. However, they suffer from power re-circulation through the Continuously Variable Unit (CVU), which reduces the overall CVT efficiency and increases the CVU contact temperatures. This, in turn, limits the CVT power rating. In this study, the CVU and the CVT design parameters are optimized simultaneously to yield the highest power capacity. The CVU power capacity estimates are based on an instantaneous CVU-contact-temperature of 180°C. It is shown that a CVU design that yields the maximum power capacity is different from a design that yields the highest CVU efficiency.
Leveraging the Equivalence of Hysteresis Models From Different Fields for Analysis and Numerical Simulation of Jointed Structures
Authors: Royston Thomas
Published: May 2009

An important problem that spans across many types of systems (e.g. mechanical and biological) is how to model the dynamics of joints or interfaces in built-up structures in such a way that the complex dynamic and energy dissipative behavior that depends on micro-scale phenomena at the joint/interface is accurately captured, yet in a framework that is amenable to efficient computational analyses of the larger macro-scale system of which the joint or interface is a (spatially) small part. Simulating joint behavior in finite element analysis by meshing the joint regions finely enough to capture relevant micromechanics is impractical for large-scale structural systems due to the prohibitively small time steps required and/or resulting matrix ill-conditioning. A more practical approach is to devise constitutive models for the overall behavior of individual joints that accurately capture their nonlinear and energy-dissipative behavior and to incorporate the constitutive response locally into the otherwise often-linear structural model. Recent studies have successfully captured and simulated mechanical joint dynamics using computationally simple phenomenological models of combined elasticity and slip with associated friction and energy dissipation, known as Iwan models. In the present article, the author reviews the relationship, and in some cases exact equivalence, of one type of Iwan model to several other models of hysteretic behavior that have been used to simulate a wide range of physical phenomena. Specifically, it is shown that the “parallel-series” Iwan model has been referred to in other fields by different names, including “Maxwell Resistive-Capacitor” and “Ishlinskii”. Given this, the author establishes the relationship of this Iwan model to several other hysteresis models, most significantly the classical Preisach model. Having established these relationships, it is then possible to extend analytical tools developed for a specific hysteresis model to all of the models with which it is related. Such analytical tools include experimental identification, inversion and analysis of vibratory energy flow and dissipation. A numerical case study of a simple system that includes an Iwan-modeled joint illustrates these points.
Response Regimes of Linear Oscillator Coupled to Nonlinear Energy Sink Under Periodic Forcing: Account of Detuning
Authors: Starosvetsky Y. , Gendelman O. V.
Published: May 2009

Dynamical system under investigation in the current work is comprised of harmonically forced linear oscillator with attached nonlinear energy sink. External forcing frequency detuning near the main resonance (1:1) is included in the system investigation. The detailed study of the periodic and quasi-periodic regimes is done in the work via (adaptive) averaging method. Local bifurcations of the periodic regimes are revealed and fully described in the space of system parameters (amplitude of excitation, damping, frequency detuning). Various possibilities of coexistence of the response regimes are predicted analytically and demonstrated numerically. Among those is a coexistence of two distinct periodic regimes together with strongly modulated response (SMR). All findings of the simplified analytic model are verified numerically and considerable agreement is observed.
A New Gerotor Design Method With Switch Angle Assignability
Authors: Yan Jia , Tong Shih-Hsi , Yang Daniel C. H.
Published: May 2009

Gerotor is generated by an oval shape generating curve which is attached to a large pitch circle rolling on an inside smaller one. For gerotor design, existing methods are able to handle arc-based generating curves with switch angle assignability. However, when dealing with non-arc-based generating curves, the current technology does not provide switch angle assignability. The switch angle is an important parameter in gerotor kinematics; it determines the angular conjugating range on the generating curve. In this paper, we developed a Deviation-Function (DF) based design method. By using this method, users can design and directly assign switch angles to both arc- and non-arc-based gerotors. Analytical formulations of both generating and gerotor profiles are derived and summarized into detailed algorithm in design steps. Some newly designed gerotor examples by using our method are provided for design and process illustration.
An Overview of Fractional Order Signal Processing (FOSP) Techniques
Authors: Chen YangQuan , Sun Rongtao , Zhou Anhong
Published: May 2009

This paper presents a brief overview of some existing fractional order signal processing (FOSP) techniques where the developments in the mathematical communities are introduced; relationship between the fractional operator and long-range dependence is demonstrated, and fundamental properties of each technique and some of its applications are summarized. Specifically, we presented a tutorial on 1) fractional order linear systems; 2) autoregressive fractional integrated moving average (ARFIMA); 3) 1/fαnoise; 4) Hurst parameter estimation; 5) fractional order Fourier transformation (FrFT); 6) fractional order linear transforms (Hartley, Sine, Cosine); 7) fractal; 8) fractional order splines; 9) fractional lower order moments (FLOM) and 10) fractional delay filter. Whenever possible, we indicate the connections between these FOSP techniques.
Classification of Periodic Solutions in a Single-Degree-of-Freedom System With Backlash
Authors: Besselink Bart , Shukla Amit , Fey Rob , Nijmeijer Henk
Published: May 2009

In this paper a single degree-of-freedom system with backlash is studied for its periodic response. This system is modeled as a piecewise linear system with discontinuity in the net restoring force, caused by additional damping in the contact-zone. The periodic orbits are classified by their number of subspace boundary crossings and Floquet multipliers. For this classification, the known analytical solutions in the different subspaces are used in the multiple shooting algorithm and a continuation method. Some observations are also presented about the qualitative features (such as symmetry, rigid body solutions) exhibited by this class of systems.
Fully-Isotropic Redundantly-Actuated Parallel Wrists With Three Degrees of Freedom
Authors: Gogu Grigore
Published: May 2009

The paper presents fully-isotropic redundantly-actuated parallel wrists (RaPWs) with three degrees of freedom. The mobile platform has three independent rotations. A method is proposed for structural synthesis of fully-isotropic RaPWs based on the theory of linear transformations. A one-to-one correspondence exists between the actuated joint velocity space and the external velocity space of the moving platform. The Jacobian mapping the two vector spaces of fully-isotropic RaPWs presented in this paper is 3×3 identity matrix throughout the entire workspace. The condition number and the determinant of the Jacobian matrix being equal to one, the manipulator performs very well with regard to force and motion transmission capabilities. Redundant actuation is used to obtain fully-isotropic parallel wrists with three degrees of freedom. As far as we are aware, this paper presents for the first time in the literature the use of redundancy to design fully-isotropic parallel wrists as well as solutions of fullyisotropic RaPWs with three degrees of freedom.
An Improved Hurst Parameter Estimator Based on Fractional Fourier Transform
Authors: Chen YangQuan , Sun Rongtao , Zhou Anhong
Published: May 2009

A fractional Fourier transform (FrFT) based estimation method is introduced in this paper to analyze the long range dependence (LRD) in time series. The degree of LRD can be characterized by the Hurst parameter. The FrFT-based estimation of Hurst parameter proposed in this paper can be implemented efficiently allowing very large data set. We used fractional Gaussian noises (FGN) which typically possesses long-range dependence with known Hurst parameters to test the accuracy of the proposed Hurst parameter estimator. For justifying the advantage of the proposed estimator, some other existing Hurst parameter estimation methods, such as wavelet-based method and a global estimator based on dispersional analysis, are compared. The proposed estimator can process the very long experimental time series locally to achieve a reliable estimation of the Hurst parameter.
Driving Performance and Strength of Pin-Rack Gear Mechanism Using a Trochoid Tooth Profile
Authors: Ikejo Kiyotaka , Nagamura Kazuteru , Tanaka Eiichirou , Yamamoto Koji
Published: May 2009

A pin-rack gear mechanism, which consists of a rack bar and a sprocket pinion, transforms a rotation motion into a liner one. The rack-bar has a series of pin train, and meshes with the sprocket pinion. In the previous study, we clarified the problem caused by using the sprocket pinion with an involute tooth profile. In this study, we adopted a trochoid tooth profile to the sprocket pinion of the pin-rack gear mechanism to obtain the higher strength. We measured the tooth root stress of the sprocket pinion with a trochoid tooth profile, the driving torque, and the horizontal force of the rack bar using a pin-rack gear mechanism testing machine. Additionally, we calculated the tooth root stress of sprocket pinion, the contact stress on the tooth surface, the flash temperature and the power loss. We considered on the driving performance and the strength of the pin-rack gear mechanism using a trochoid tooth profile by comparing the measured data with the calculated results.
Driving Performance of High Reduction Planetary Gear Drive With Meshing of Arc Tooth Profile Gear and Pin Roller
Authors: Nagamura Kazuteru , Ikejo Kiyotaka , Tanaka Eiichirou , Hirai Takamasa , Koumori Toshiyuki , Kamimura Ichiro
Published: May 2009

This paper describes a new type planetary gear drive with the high reduction ratio. The planetary gear drive is mechanically similar to a 2S-C type planetary gear, which has two sun gears and one carrier. The planetary gear drive has two pairs of an arc tooth profile gear and a pin roller, which mesh each other. The planetary gear drive has little backlash, a high efficiency, a long fatigue limit, etc., because the tooth contact holds on concave and convex surfaces. In this study, we measured the vibration acceleration, the transmission error, the gear noise, and the efficiency on the new type planetary gear drive by the running test. We discuss and report the driving performance of the planetary gear drive.