bluuebunny/crossref_metadata_2025 huggingface dataset:
Education and Internet Integration of 3D-CAD Design and Manufacturing for Complex Products
Authors: Sakamoto Haruo , Yanamoto Yukari
Published: May 2009

This paper describes Internet integration for 3D-CAD design and manufacturing for complex products. The Kochi University of Technology (KUT) in Kochi, Japan, has collaborated with a company (Sakamoto Giken Co. in Kochi), who in turn has collaborated with other companies using Internet technology in the field of design and manufacturing. Using collaborative software installed in the company, an Internet camera, and an Internet telephone, design meetings among engineers at distant locations were conducted. Several cases of collaborative design and manufacturing work are introduced. The company aims to produce complex products that are difficult to design and manufacture. In addition to describing such collaborative work among industries or between industries and universities, the importance of education in 3D-CAD and manufacturing, as well as some actual trials of design education, are introduced. 3D-CAD, manufacturing, and rapid prototyping have been utilized in activities between universities and companies as well as among companies. The use of Internet technology in this way reduces the time required for design and manufacturing and accelerates product development.
Mechanical Properties of Electrospun Carbon Nano Fiber (ECNF)/Epoxy Nanocomposites
Authors: Aussawasathien Darunee , Sancaktar Erol
Published: May 2009

Electrospun polyacrylonitrile (PAN) fiber precursor based Carbon Nanofiber (CNF) mats were produced and impregnated with epoxy resin. The mechanical properties of as-prepared nanofibers in the mat and short fiber filled epoxy nanocomposite forms were determined to demonstrate the effect of fiber aspect ratio and interconnecting network on those properties. Our experimental results reveal that epoxy nanocomposites containing Electrospun Carbon Nano Fibers (ECNF) with high fiber aspect ratio and high interconnecting network in the non-woven mat form yield better mechanical properties than those filled with short ECNFs. The ECNF mat in epoxy nanocomposites provides better homogeneity, more interlocking network, and easier preparation than short ECNFs. Mechanical properties of ECNF mat-epoxy nanocomposites, which we obtained using tensile and flexural tests, such as stiffness and modulus increased, while toughness and flexural strength decreased, compared to the neat epoxy resin. Dynamic Mechanical Analysis (DMA) results showed, higher modulus for ECNF mat-epoxy nanocomposites, compared to those for neat epoxy resin and short ECNF-epoxy nanocomposites. The epoxy nanocomposites had high modulus, even though the glass transition temperature, Tg values dropped at some extents of ECNF mat contents when compared with the neat epoxy resin. The cure reaction was retarded since the amount of epoxy and hardener decreased at high ECNF contents together with the hindering effect of the ECNF mat to the diffusion of epoxy resin and curing agent, leading to low crosslinking efficiency.
Frequency Locking in a Forced Mathieu-van der Pol-Duffing System
Authors: Pandey Manoj , Rand Richard H. , Zehnder Alan T.
Published: May 2009

Optically actuated Radio Frequency MEMS devices are seen to self oscillate or vibrate under illumination of sufficient strength [1]. These oscillations can be frequency locked to a periodic forcing, applied through an inertial drive at the forcing frequency, or subharmonically via a parametric drive, hence providing tunability. In a previous work [2] this MEMS device was modeled by a three dimensional system of coupled thermomechanical equations requiring experimental observations and careful finite element simulations to obtain the model parameters. The resulting system of equations is relatively computationally expensive to solve which could impede its usage in a complex network of such resonators. In this paper we present a simpler model which shows similar behavior to the MEMS device. We investigate the dynamics of a Mathieu-van der Pol-Duffing equation, which is forced both parametrically and non-parametrically. It is shown that the steady state response can consist of either 1:1 frequency locking, or 2:1 subharmonic locking, or quasiperiodic motion. The system displays hysteresis when the forcing frequency is slowly varied. We use perturbations to obtain a slow flow, which is then studied using the bifurcation software package AUTO.
Analysis and Design of Smart Structures to Control Vibration and Noise
Authors: Gabbert Ulrich , Lefe`vre Jean , Nestorovic´ Tamara , Ringwelski Stefan
Published: May 2009

The paper presents an overall analysis and design approach for smart lightweight structures to actively reduce vibration and noise. As smart materials, distributed piezoelectric patches are attached to the structure. The basis of the approach is an overall finite element model, which includes the structure itself, the acoustic fluid, the piezoelectric actuators and sensors as well as the controller. As a test example a smart acoustic box is simulated and the simulation results are compared with measured data. Finally, also industrial applications are briefly presented.
Tabu Search Algorithm and Reduced Design Space Methods for Optimum Synthesis of Compliant Mechanisms
Authors: Smaili Ahmad , Hassanieh Mazen
Published: May 2009

An approach to design compliant mechanisms starting from rigid-body solution is presented in this work. However, instead of starting the optimization with a topology of fully populated rectangular grid of finite elements, the method begins with a design region that the links of the corresponding rigid-body mechanism (RBM) are likely to occupy as the mechanism traverses the intended task. The aim is to reduce the complexity of topology optimization by reducing the number of design variables. Several space reduction ideas and associated objective criteria are presented. A tabu-gradient algorithm is developed and adapted to solve the optimization problem. Several examples are given to demonstrate the proposed method.
Vibration Suppression of Mistuned Coupled-Blade-Disk Systems Using Piezoelectric Circuitry Network
Authors: Yu Hongbiao , Wang K. W.
Published: May 2009

In this research, piezoelectric networking is investigated as an effective means for vibration suppression of mistuned bladed disk systems. Due to mistuning (i.e., imperfections in blade properties), bladed disks in turbo-machinery often suffer from vibration localization. In such cases, the vibration energy is confined to a small number of blades and forced response can be drastically increased when the structure is under engine order force excitation. To suppress the excessive vibration caused by localization, a piezoelectric networking concept has been proposed and analyzed for a multi-blade system in a previous study by the authors [1]. This research further extends the investigation with focus on circuitry design for a complex bladed disk model with the consideration of coupled blade-disk dynamics. A new multi-circuit piezoelectric network is designed and analyzed for multiple-harmonic vibration suppression of bladed disks. An optimal network is derived analytically based on system analysis. The performance of the network for bladed disks with random mistuning is examined using Monte Carlo simulation. The effects of variations (mistuning and detuning) in circuit parameters are also studied. Finally, a method to improve system performance and robustness is discussed.
A Further Study on High Contact Ratio Spur Gears in Mesh With Double Scope Tooth Profile Modification
Authors: Wang Jiande , Howard Ian
Published: May 2009

Compared to the commonly used Low Contact Ratio Spur Gears (LCRG), High Contact Ratio Spur Gears (HCRG) can provide higher power to weight ratio, and can also achieve smoother running with lower Transmission Error (TE) variations. To achieve the benefits of High Contact Ratio Spur Gears (HCRG), its tolerance to manufacturing errors and elastic deformation has to be increased. After various attempts by previous researchers, double scope tooth profile modifications have been seen as being of major interest showing great potential for improvements in most applications. Research presented in this paper concentrated on providing further proofs and verifications on the topic by using modern numerical methods and comprehensive analysis. Additionally, a general Bulk Tooth Rotation (BTR) type tooth profile modification is introduced and applied to the High Contact Ratio Spur Gears (HCRG) in order to improve the tooth profile design and some common higher order analysis is shown allowing further comments to be made.
A Euclidean Invariants Based Study of Circular Surfaces With Fixed Radius
Authors: Cui Lei , Wang Delun
Published: May 2009

In this paper a complete system of Euclidean invariants is presented to study circular surfaces with fixed radius. The study of circular surfaces is simplified to the study of two curves: the spherical indicatrix of the unit normals of circle planes and the spine curve. After the geometric meanings of these Euclidean invariants are explained, the distribution parameter of a circular surface is defined. If the value of the distribution parameter of a circular surface is 0, the circular surface is a sphere. Then the relationship between the moving frame {E1, E2, E3} and the Frenet frame {t, n, b} of the spine curve is investigated, and the expressions of the curvature and torsion of the spine curve are obtained based on these Euclidean invariants. The fundamental theorem of circular surfaces is first proved. Next the first and second fundamental forms of circular surfaces are computed. The last part of this paper is devoted to constraint circular surfaces. The sufficient and necessary condition for a general circular surface to be one that can be generated by a series-connected C’R, HR, RR, or PR mechanism is proved.
The Bending and Surface Contact Stress Variations in a Mating Plastic Gear Pair
Authors: Lin Ah-Der , Kuang Jao-Hwa
Published: May 2009

A dynamic model of an engaging spur gear pair is proposed to study the distributions and variation of bending and surface contact stresses around the fillet and contacting points for plastic gears. The parameters used in this dynamic model include time-varying mesh stiffness, frictional coefficient, and profile-shifted factor, etc. Due to high sensitivity to heat for plastic material, the influence of temperature on plastic gears has also been taken into consideration in this work. A computational algorithm is developed to simulate the variation of fillet bending and surface contact stresses during the engagement with different speeds. The results indicate that the operating temperature may affect the distribution and the magnitude of bending and surface contact stresses of a plastic gear pair significantly.
Non-Linear Vibrations of Multi-Stage Bladed Disks Systems With Friction Ring Dampers
Authors: Laxalde Denis , Thouverez Fabrice
Published: May 2009

In this paper, we study the non-linear dynamics of a multi-stage system of turbomachinery bladed disks with friction dampers. We focus on the quasi-periodic forced response of this system under multi-frequency rotating excitations. The system’s equations of the motion are expressed in the multi-frequency domain using a multi-frequency harmonic balance method in combination a multi-stage cyclic symmetry reduction. A Dynamic Lagrangian formulation in alternating frequency/time domains is also used for the calculation of the contact and friction forces. In applications we consider a system of two HP compressor stages of integrally bladed disks with friction ring dampers.
Automotive Collision Mitigation Through Vehicle Dynamic Control
Authors: Hogan Ian , Manning Warren
Published: May 2009

The ever important development of automotive crash mitigation systems has, over recent years, lead to the development of Advance Driver Assistance (ADA) systems. These systems use a variety of approaches to help avoid vehicle collision from occurring. However, these systems are still far from being able to prevent all collisions from occurring in the current environment. This work aims to use vehicle dynamic control systems to optimize the vehicle’s dynamic characteristics for an impending collision. This will utilize the detection systems developed for these ADA systems, to detect when an imminent collision has become unavoidable. To perform such studies, it is important to have a vehicle dynamic simulation that can also include the vehicle crash structural dynamics. These factors are key to analysing the point-of-impact and post-impact vehicle dynamics and the effects on the outcome of the impact. This paper outlines the initial development of a multibody vehicle dynamic crash analysis model. This enables the analysis of a generic vehicle dynamic model, together with a simple crash model, so that the effects of a variety of simple dynamic control approaches can be analysed. This will give a valuable insight into the effects of vehicle dynamic control on the collision severity. Initial results show that this simple and fast method of simulating both the vehicle dynamics and crash dynamics in a simple multibody model can be an effective and accurate tool for generic vehicle analysis. Results also show that even simple vehicle dynamic controls during the pre-impact, impact and post-impact stages of the collision can have a significant effect on the impact severity.
A Method for Benchmarking Product Family Design Alternatives
Authors: Thevenot Henri J. , Simpson Timothy W.
Published: May 2009

Today’s companies are pressured to develop platform-based product families to increase variety while keeping production costs low. Determining why a platform works, and alternatively why it does not, is an important step in the successful implementation of product families and product platforms in any industry. Internal and competitive benchmarking is essential to obtain knowledge of how successful product families are implemented, thus avoiding potential pitfalls of a poor product platform design strategy. While the two fields of product family design and benchmarking have been growing rapidly lately, we have found few tools that combine the two for product family benchmarking. To address this emerging need, we introduce the Product Family Benchmarking Method (PFBenchmark) to assess product family design alternatives (PFDAs) based on commonality/variety tradeoff and cost analysis. The proposed method utilizes the Comprehensive Metric for Commonality developed in previous work to assess the level of commonality and variety in each PFDA, as well as the corresponding manufacturing cost. The method compares not only (1) existing PFDAs but also (2) the potential cost savings and commonality/variety improvement after redesign using two plots — the Commonality/Variety Plot and the Cost Plot — enabling more effective comparisons across PFDAs. An example of benchmarking two families of valves is presented to demonstrate the proposed method.
A Simulation Interface for Integrating Real-Time Vehicle Control With Game Engines
Authors: Scrapper Christopher J. , Proctor Frederick M. , Balakirsky Stephen
Published: May 2009

This paper describes the use of video game engines as simulation environments that aid the development and testing of real-time vehicle controllers. The use of game engines for simulation is surveyed, with relevant technologies noted. The need to switch between different vehicle controllers, game engines and real vehicles gave rise to an integration architecture. The features of the architecture are described, including the execution model, message set and knowledge base. Adaptation of existing controllers, simulations and vehicles to this architecture is discussed. Issues of performance and scalability are addressed. An example is provided to illustrate the concepts.
A Fuzzy Synthesis Control Scheme and Optimization for Vehicle Dynamic Stability System
Authors: Zhang Yunqing , Gao Si , Li Lingyang , Chen Liping , Yang Jingzhou , Abdel-Malek Karim
Published: May 2009

Vehicle stability control system can enhance the vehicle stability and handling in the emergency situations through the control of traction and braking forces at the individual wheels. This paper presents a Fuzzy synthesis control strategy with an ideal 2-DOF linear model and optimization of the control parameters. The control strategy consists of Fuzzy control of two control objectives (yaw velocity ω and sideslip angle β). Fuzzy functions can adjust and control these two objectives and through Matlab Fuzzy control unit & ADAMS multi-body vehicle dynamic model we obtain optimized simulation. The co-simulation scenario is on iced road with a single sine steering angle input and in a high speed. The control parameters are optimized and analyzed by a combined optimization algorithm (Genetic Algorithm (GA) and Nonlinear Programming Quadratic Line search (NLPQL) method) combined with response surface model (RSM). The simulation results show that the handling stability and safety of the vehicle can be enhanced by the Fuzzy control method that can adapt complex road and driving conditions.
Nonlinear Constitutive Models and the Finite Element Absolute Nodal Coordinate Formulation
Authors: Maqueda Luis G. , Shabana Ahmed A.
Published: May 2009

In this investigation, the use of three different nonlinear constitutive models based on the hyper-elasticity theory with the absolute nodal coordinate formulation is considered. These three nonlinear constitutive models are based on the Neo-Hookean constitutive law for compressible materials, the Neo-Hookean constitutive law for incompressible materials, and the Mooney-Rivlin constitutive law in which the material is assumed to be incompressible. These models, which allow capturing Poisson modes, are suitable for many materials and applications, including rubber-like materials and biological tissues which are governed by nonlinear elastic behavior and are considered incompressible or nearly incompressible. Numerical examples that demonstrate the implementation of these nonlinear constitutive models in the absolute nodal coordinate formulation are presented. The results obtained using the nonlinear and linear constitutive models are compared in this study. The results show that when linear constitutive models are used in the large deformation analysis, singular configurations are encountered and basic formulas such as Nanson’s formula are no longer valid. These singular deformation configurations are not encountered when the nonlinear constitutive models are used.
Implementation of Low Computational Cost Nonlinear Formulation for Multibody Railroad Vehicle Systems
Authors: Sanborn Graham G. , Heineman Jason R. , Shabana Ahmed A.
Published: May 2009

In a companion paper [1], a low computational cost nonlinear formulation was presented to for the analysis of the forces of long trains. The formulation allows systematically changing the number of degrees of freedom of each rail car and includes the force inputs that are typically found in railroad applications. In this paper, the implementation of this nonlinear formulation is described. A computer interface is also developed in order to allow the user to operate a virtual train model in real time and also change the model parameters and car connectivity conditions. Numerical results are presented in order to demonstrate the use of the formulation proposed and its computer implementation.
A Large Deflection Analysis Method for Lateral Torsional Buckling
Authors: Chase Robert P. , Todd Robert H. , Howell Larry L. , Magleby Spencer P.
Published: May 2009

Research is presented on describing the deflection behavior of prismatic beams with high aspect ratio rectangular cross-sections undergoing lateral torsional buckling. The 3-D large deflection path of buckling beam tips was closely approximated by circular arcs in two planes. When deflection paths of beams with different geometric and material properties were nondimensionalized with respect to the beam length, these deflection paths were the same with very little variation. Similarly, the change in the beam tip orientation as the beams deflected also remained the same as geometry and material properties were varied.
Experimental Investigation of Nonplanar Chaotic Vibrations in a Cantilever Beam With Vertical Base Excitation
Authors: Zhang Wei , Cao Dong-Xing , Hu Bin , Yao Ming-Hui , Fan Jin-Hong
Published: May 2009

The experimental results of the nonlinear nonplanar periodic and chaotic vibrations are demonstrated for a cantilever beam with square cross-section under harmonic vertical base excitation. It is illustrated that this simple system can exhibit complicated dynamics, including periodic doubling bifurcation and chaotic motion. The experimental results also indicate that there indeed exist the multi-pulse Shilnikov type chaotic motions for the nonlinear nonplanar oscillations of the cantilever beam in three-dimensional phase space. It is verified that the phenomena of the multi-pulse Shilnikov type jumping orbits detected by the theoretical analysis indeed exist in the nonplanar nonlinear motion of the cantilever beam subjected to a harmonic vertical base excitation at the fixed end.
Networked Fuzzy Control System for a High-Performance Drilling Process
Authors: Haber Rodolfo E. , Haber-Haber Rodolfo , Escribano Angel , Escribano Javier
Published: May 2009

In order to improve drilling efficiency while preserving tool life, the current study focuses on the design and implementation of a simple, optimal fuzzy-control system for drilling force. The main topic of this study is the design and implementation of a networked fuzzy controller. The control system consists of a two-input (force error and change of error), single-output (feed-rate increment) fuzzy controller. The control algorithm is connected to the process through a multipoint interface (MPI) bus. The output (i.e., feed-rate) signal is transmitted through the MPI; therefore, network-induced delay is unavoidable. The optimal tuning of the fuzzy controller using a maximum known delay is based on the integral time absolute error (ITAE) criterion. The main advantage of the approach presented herein is the design of a simple fuzzy controller using a known maximum allowable delay to deal with uncertainties and nonlinearities in the drilling process and delays in the network-based application. The results demonstrate that the proposed control strategy provides an excellent transient response without overshoot and a slightly higher drilling time than the CNC working alone (uncontrolled). Therefore, the fuzzy-control system reduces the influence of the increase in cutting force and torque that occurs as the drill depth increases, thus eliminating the risk of rapid drill wear and catastrophic drill breakage.
Research on Coupling Faults With Oil-Film Instability and Bearing Rub-Impact Based on Reassigned Wavelet Scalogram
Authors: Li Xiaopeng , Ma Hui , Song Guiqiu , Wen Bangchun
Published: May 2009

An experiment rig was set up to simulate coupling faults with oil-film instability and local rub-impact. The collected vibration signals were roughly analyzed by 3-D waterfall spectra. In complicated frequency components domain, the vibration signals were analyzed with wavelet scalogram and reassigned wavelet scalogram. Results show that reassigned wavelet scalogram has higher time-frequency resolution than wavelet scalogram and can well identify such close low-frequency components. The analysis results also indicated rub-impact faults induced by oil-film instability can produce some low-frequency components with small amplitude and oil whip can produce half frequency component; rub-impact with a common extent exerts a light influence on rotor systems and nonlinear oil-film force plays a decisive role in rotor systems.
Nonlinear Vibration and Bifurcation Analysis for Rotor-Seal-Bearing Systems of Centrifugal Compressors
Authors: Wang Yuefang , Li Yong , Zhang Yong , Wang Xiaoyan
Published: May 2009

This paper presents the nonlinear coupling vibration and bifurcation of a high-speed centrifugal compressor with a labyrinth seal and two journal bearings. The rotor system is modeled as a Jeffcott rotor. The Muszynska’s model is used to express the seal force with multiple parameters. For the journal bearings, the model proposed by Zhang is adopted to express the excitation of unsteady oil-film force. The Runge-Kutta method is used to determine the vibration responses at the disc center and the two bearings. With parameters of rotation speed and pressure difference of the seal, bifurcation diagrams are presented to demonstrate the complexity in the rotor motions. Multiple periodic bifurcations are pointed out using two seal pressure differences. The intricate bifurcation behavior shows inherent interactions between forces of oil-film and seal, which reflect much more complicated rotor dynamics than the one with either of the excitations alone.
Hybrid Simulation of Use Processes With Scenario Structures and Resource-Integrated Models
Authors: van der Vegte Wilhelm F. , Rusa´k Zolta´n
Published: May 2009

The approach described in this paper aims to offer designers a new way to investigate use processes of a product, by integrating scenarios of expected user behavior with simulations of artifact behavior. We introduce a method and system framework to model and simulate virtual human-artifact systems, aiming to resolve two knowledge-related issues in use-process simulation: (i) the integration of distinct modeling and simulation approaches (ii) extending the deployability of simulations towards conceptual design. This paper elaborates on achievements in the first area. Currently, performing complete-picture simulations in which the product and the human user react on each other’s behaviors is not practicable. To make this possible, a hybrid approach is proposed. Behavior that is commonly modeled based on the laws of physics is simulated as continuous behavior, while information-processing behavior is simulated as discrete behavior. Discrete behavior is represented by finite state machines, which are behavioral models encompassing human decision-making and information-processing by artifacts. They enable the designer to perform what-if studies involving different ‘scenario structures’ of human decisions during simulated use, and thus to address an important factor contributing to the diversity of use processes. For continuous (physical) behavior multibody dynamics simulation and simulation with discretized 3D object models can be considered. A pilot study of a basic use process showed that our concept of hybrid simulation successfully enables investigation of multiple courses of use processes. However, the applicability of multibody simulation turned out to be limited, because of the crucial role of large deformations in human-artifact interaction. To overcome these limitations, discretized models are proposed for the next steps towards building a full-fledged system.
Adaptive Suppression of Torque Harmonics in Brushless Motors
Authors: Aghili Farhad
Published: May 2009

Accurate torque control of a brushless motor requires the motor’s torque characteristics, which can be captured by a periodic function in motor angle. This paper presents a direct adaptive controller for torque control of brushless motors, which estimates the Fourier coefficients of the periodic function based on the measurements of motor phase voltage and angle. It will be analytically shown that the proposed adaptive controller achieves torque tracking regardless of the trajectories of input signals. Moreover, the adaptive controller does not rely on the modeling of the mechanical load, and that makes control implementation simple and modular. Experimental results obtained from the McGill/MIT motor have demonstrated that motor torque converges to the command torque.
Discrete Mechanics and Optimal Control for Constrained Multibody Dynamics
Authors: Leyendecker Sigrid , Ober-Blo¨baum Sina , Marsden Jerrold E. , Ortiz Michael
Published: May 2009

This paper formulates the dynamical equations of mechanics subject to holonomic constraints in terms of the states and controls using a constrained version of the Lagrange-d’Alembert principle. Based on a discrete version of this principle, a structure preserving time-stepping scheme is derived. It is shown that this respect for the mechanical structure (such as a reliable computation of the energy and momentum budget, without numerical dissipation) is retained when the system is reduced to its minimal dimension by the discrete null space method. Together with initial and final conditions on the configuration and conjugate momentum, the reduced time-stepping equations serve as nonlinear equality constraints for the minimisation of a given cost functional. The algorithm yields a sequence of discrete configurations together with a sequence of actuating forces, optimally guiding the system from the initial to the desired final state. The resulting discrete optimal control algorithm is shown to have excellent energy and momentum properties, which are illustrated by two specific examples, namely reorientation and repositioning of a rigid body subject to external forces and the reorientation of a rigid body with internal momentum wheels.
Development of a Flexible Educational Mechatronic System Based on xPC Target
Authors: Tahboub Karim A. , Albakri Mohammad I. , Arafeh Aziz M.
Published: May 2009

In this article an educational embedded mechatronic system based on the MATLAB xPC target is presented. xPC target, a tool provided by MATLAB and its Simulink toolbox, offers a practical means for developing a hardware-in-the-loop (HIL) simulation environment. Since ordinary personal computers (PCs) can be used for modeling, analysis, design, monitoring, and control of the process, the setup becomes suitable for rapid-prototyping, research, and educational use. An application example of a double inverted pendulum on a cart that is digitally controlled is presented and discussed. The system is fully implemented by means of two PCs, MATLAB, Simulink, xPC target, a data acquisition card, an AC servomotor, and three optical encoders. It is shown that, through this technology, high sampling frequencies can be obtained by even using a Pentium III PC. Tele monitoring and control through a network are demonstrated.
Computational Study of the Air/Fuel Mixture in a Small Spark Ignition Engine
Authors: Caulfield Suzanne , Amano Ryo S.
Published: May 2009

In an effort to understand the fluid dynamics in the droplet formation process, during the fuel delivery portion of operation of a small spark ignition engine, a computational study of the process was undertaken. A combination of high-speed photography and Computational Fluid Dynamics was used to investigate the droplet formation process. Droplets of liquid are stripped from a column of liquid and entrained in a high velocity, cross-flow air stream. This process is known as aerodynamic stripping. This aerodynamic stripping is the process by which fuel is metered and delivered to a spark ignition engine. The condition of the fuel and air mixtures has an impact on the combustion event in the engine. Therefore, a thorough understanding of the fuel delivery process is desirable. This paper details a comprehensive CFD model that was created to explore the possibility of modeling the droplet breakup process. The mesh density required for this analysis was investigated. The accuracy of the predictions was verified by comparing the CFD results with high-speed film taken of the process. The results show that the process can be modeled accurately, provided the correct size mesh is used, and that the predicted droplets compare well with those seen in the film.
Center Manifold Reduction of Periodic Delay Differential Systems
Authors: Butcher Eric A. , Deshmukh Venkatesh , Bueler Ed
Published: May 2009

A technique for center manifold reduction of nonlinear delay differential equations (DDEs) with time-periodic coefficients is presented. Perturbation expansion converts the nonlinear response problem into solutions of a series of non-homogenous linear ordinary differential equations (ODEs) with time periodic coefficients. One set of linear non-homogenous ODEs is solved for each power of the perturbation parameter. Each ODE is solved by a Chebyshev spectral collocation method. Thus we compute a finite approximation to the nonlinear infinite-dimensional map for the DDE. Center manifold reduction on the map is then carried out. Center manifold reduction is illustrated via a single inverted pendulum including both a periodic retarded follower force and a nonlinear restoring force. In this example, the amplitude of the limit cycle associated with a flip bifurcation is found analytically and compared to that obtained from direct numerical simulation.
The Optimum Design of Hydrodynamic Lubrication Bearing for Minimization of the Total Life Cost
Authors: Iwatsubo Takuzo , Yamabayashi Jun
Published: May 2009

This paper proposes an optimum design method of journal bearing for minimizing the total life cost which includes not only the initial cost but also the running cost. Journal bearing is one of the typical friction part and physically severe part in machine elements. Therefore, maintenance is required to prevent failure and to keep performance. For this object, the running cost by the maintenance is user’s burden. Thus, the optimum design method of the bearing for minimization of the total life cost is required. In this research, the evaluation functions of the total life cost which contains the initial cost and the running cost of the bearing are discussed and the optimum design is proposed under the physical constrain, that is Thermo Hydrodynamic Lubrication theory (THL theory), and inequality constraints. Then design valuables of the optimum journal bearing are obtained.
Forward and Inverse Displacement Analysis of a Novel Three-Legged Mobile Robot Based on the Kinematics of In-Parallel Manipulators
Authors: Ren Ping , Morazzani Ivette , Hong Dennis
Published: May 2009

This paper presents the forward and inverse displacement analysis of a novel three-legged walking robot STriDER (Self-excited Tripedal Dynamic Experimental Robot). STriDER utilizes the concept of passive dynamic locomotion to walk, but when all three feet of the robot are on the ground, the kinematic structure of the robot behaves like an in-parallel manipulator. To plan and control its change of posture, the kinematics of its forward and inverse displacement must be analyzed. First, the concept of this novel walking robot and its unique tripedal gait is discussed including strategies for changing directions, followed by the overall kinematic configuration and definitions of its coordinate frames. When all three feet of the robot are on the ground, by assuming there are no slipping at the feet, each foot contact point are treated as a spherical joint. Kinematic analysis methods for in-parallel manipulators are briefly reviewed and adopted for the forward and inverse displacement analysis for this mobile robot. Both loop-closure equations based on geometric constraints and the intersection of the loci of the feet are utilized to solve the forward displacement problem. Closed-form solutions are identified and discussed in the cases of redundant sensing with displacement information from nine, eight and seven joint angle sensors. For the non redundant sensing case using information from six joint angle sensors, it is shown that closed-form solutions can only be obtained when the displacement information is available from non-equally distributed joint angle sensors among the three legs. As for the case when joint angle sensors are equally distributed among the three legs, it will result in a 16th-order polynomial of a single variable. Finally, results from the simulations are presented for both inverse displacement analysis and the non redundant sensing case with equally distributed joint angle sensors. It was found that at most sixteen forward displacement solutions exist if displacement information from two joint angle sensors per leg are used and one is not used.
Automation of Structuring and Research of Lever Mechanisms Kinematics
Authors: Kuzlyakina Valentina V. , Slepenko Jury N.
Published: May 2009

The procedure of lever mechanisms structuring being the basis of the majority of mechanical systems is complicated and labor-consuming. The generalized structural modules allow to automate and repeatedly to speed up process of lever mechanisms schemes creation and research of their kinematics in the specialized system “Visual Structure Editor (VSE)”. Ten types of generalized structural modules are offered, which allow to create schemes and to investigate kinematics of lever mechanisms of the second class of any degree of complexity. In this work structuring of various flat mechanisms schemes with any possible number of members based on only 5 types of generalized structural groups is presented. These are a rotating initial link, an onward moving link, a two-driver group with three rotary kinematics couples and two-driver groups with two rotary and one external forward kinematics couples of two types. VSE is broadly used in education process when performing the course designing on engineering discipline.
Bifurcation and Chaos Behavior of Rotor-Bearing System With Crack and Pedestal Looseness Faults
Authors: Luo Yuegang , Zhang Songhe , Wen Feng , Wen Bangchun
Published: May 2009

A dynamic model was set up for the two-span rotor-bearing system with coupling faults of crack and pedestal looseness supported on three plain journal bearings. The nonlinear dynamic behaviors that induced by crack, pedestal looseness and coupling faults are numerically studied. There is quasi-periodic motion appearing in the cracked rotor-bearing system, and it within the sub-critical speed range in the pedestal looseness rotor-bearing system. There is chaotic motion appearing within the supper-critical speed range in the pedestal looseness rotor-bearing system. The pedestal looseness fault is the main influence on the coupling faults system, and there is Period-3 motion appearing in the system. The results may bring up theoretical references for fault diagnoses, dynamic design, and security running to rotor-bearing system.
Generic Mobility of Rigid Body Mechanisms: On the Existence of Overconstrained Mechanisms
Authors: Mu¨ller Andreas
Published: May 2009

In this paper the generic DOF of mechanisms is investigated. This is the DOF of almost all mechanisms, that can be built from a given set of kinematic pairs in a certain arrangement, but with arbitrary link geometry. In particular, this is the most likely DOF in the presence of link imperfections. The local DOF of a mechanism is the dimension of its configuration space. The differential DOF is the number of linearly independent velocity constraints. It is pointed out, that the local DOF can not always be inferred from the number of constraints (overconstrained mechanisms) nor can the differential DOF always be deduced from the local DOF. It is proven, that the generic DOF of a mechanism is given by the Chebychev-Kutzbach-Gru¨bler formula δ=Σαfa−g(j−b+1), with b and j the number of bodies and joints, and fα the DOF of joint α. Consequently, almost all mechanism are trivial, i.e. not overconstrained.
Evidence Theory-Based Reliability Analysis and Optimization in Engineering Design
Authors: Du Li , He Liping , Huang Hong-Zhong
Published: May 2009

Engineering design under uncertainty has gained considerable attention in recent years. There exist two different types of uncertainties in practical engineering applications: aleatory uncertainty that is classified as objective and irreducible uncertainty with sufficient information on input uncertainty data and epistemic uncertainty that is a subjective and reducible uncertainty that is caused by the lack of knowledge on input uncertainty data. Among several alternative tools to handle uncertainty, evidence theory has proved to be computationally efficient and stable tool for reliability analysis and design optimization under aleatory and/or epistemic uncertainty involved in engineering systems. This paper attempts to give a better understanding of uncertainty in engineering design with a general overview. The overview includes theoretical research, computational development, and performable ability consideration of evidence theory during recent years. At last, perspectives on future research are stated.
Effects of Powders on the Precision of a Powder Metallurgy Helical Gear
Authors: Yu Ming-Ta , Tsay Chung-Biau
Published: May 2009

This study refers to the conditions of practical powder metallurgy manufacture process, and proceeds to experiments and gear precision measurements as well as investigation on the effects of two parameters, powders and pitch circle radius, on gear precision. The relationship between gear parameters and gear surface deviations was derived from the mathematical model of the involute helical gear and the analysis of gear surface deviations. In accordance with the measurement results of experiments, an ideal correction on the parameters of a forming die is obtained from the computer simulations of gear surface deviations.
Fuzzy Analytical Hierarchy Process-Based Assembly Unit Partition for Complex Products
Authors: Liu Jihong , Wang Yong
Published: May 2009

Assembly planning is one of the NP complete problems, which is even harder to solve for complex products. Furthermore, development of complex products has been becoming a collaborative activity among different enterprises at the same or different sites. Collaboration among designers is considered as an effective strategy to tackle the difficulty of assembly planning. According to the strategy, the task of assembly planning of complex products is decomposed into several simpler subtasks related to portions of the whole product, and the subtasks are then assigned to the designers in collaboration. In this paper, assembly unit partition is addressed, which means the decomposition of a complex product into smaller assembly units. Assembly unit partition is more complex than subassembly extraction (or identification) because more assembly constraints are taken into consideration. Firstly, different and necessary assembly constraints are analyzed in detail and their related evaluation indices are given for assembly unit partition. Then, the assembly unit model and the decision model of assembly unit partition are proposed. A method of assembly unit partition based on the decision model and Fuzzy Analytical Hierarchy Process (FAHP) method is clarified. The valid assembly units can be determined by analyzing the decision values of assembly relations between two parts and the given conditions. Finally, the validity and effectiveness of the method is verified with an example.
Ride Dynamics of a Flexible Multibody Model of an Urban Bus
Authors: Georgiou G. , Badarlis A. , Natsiavas S.
Published: May 2009

Dynamic response of a large order mechanical model of an urban bus is investigated. The emphasis is first put on developing a quite complete model, which can be utilized in order to extract sufficiently reliable and accurate information related to its dynamics in a fast way. Since some of the components of the bus undergo large rigid body rotation, in addition to motion resulting from their deformability, a multibody dynamics framework is adopted. This implies that the resulting equations of motion appear in the form of a strongly nonlinear set of differential-algebraic equations, which are difficult to handle even numerically. In fact, the modeling becomes more involved because all the significant nonlinearities appearing in the interconnections of the structural components and especially in the front and rear suspension subsystems of the bus are taken into account. In order to alleviate some of these complexities, the number of degrees of freedom of each component, associated with its deformability, is reduced drastically by applying an appropriate coordinate condensation methodology. Finally, this model is employed and numerical results are obtained for motions resulting from typical road excitation. In particular, selected response quantities related to ride comfort are examined for characteristic combinations of the bus suspension stiffness and damping parameters.
Acoustical Radiation Calculation of Complex Structures Using Finite Element Methods
Authors: Viallet Marianne , Poume´rol Ge´rald , Dessombz Olivier , Jezequel Louis
Published: May 2009

Predicting noise is a step that cannot be ignored in automotive industry during vehicle design cycle. This is classically achieved through Finite Element and Boundary Element methods. When dealing with exterior problems, Boundary Element Method is quite efficient but may induce ill-conditioned equations. On the other hand, Finite Element Method, if easier to handle is not basically adapted to unbounded media. In this paper a new method, which tries to combine advantages of both techniques is presented. This method, inspired from Substructure Deletion Method, which is well-known in Civil Engineering, consists in dividing a complex unbounded problem into two easier ones to solve finite and infinite problems. Instead of considering a geometrically complex structure straightforward, a prismatic bounding volume is first studied using BEM. Then a classical Finite Element computation is performed on the volume left between the box and the structure of interest. Advantage of this technique is that when testing and comparing several geometries contained in such a box, only one boundary element calculation is needed. Efficiency of this method is discussed in the present document. Here instead of using Boundary Element Methods to solve the exterior problem, an original use of Finite Elements is made. Efficiency of this new version of the Substructure Deletion Method is discussed.
Nonlinear Vibration in a Vertical Rigid Rotor Supported by the Magnetic Bearing: Case Considering the Delays of Both Electric Current and Magnetic Flux
Authors: Inoue Tsuyoshi , Sugiyama Motoki , Sugawara Yasuhiko , Ishida Yukio
Published: May 2009

Active magnetic bearing (AMB) becomes to be widely used in various kinds of rotating machinery. However, as the magnetic force is nonlinear, nonlinear phenomena may occur when the rotating speed becomes higher and delay of control force increases. In this paper, the magnetic force is modeled by considering both the second order delay of the electric current and the first order delay of the magnetic flux, and the AMB force is represented by a power series function of the electric current and shaft displacement. The nonlinear theoretical analysis of the vertical rigid rotor supported by AMB is demonstrated. The effects of the delays and other AMB parameters on the nonlinear phenomena are clarified theoretically and experimentally.
Vibration Analysis and Detection of Rotor Crack in a Multi-Disk Rotor System by Periodic Excitation Using AMB
Authors: Inoue Tsuyoshi , Yamamichi Toshihiro , Kato Masato , Ishida Yukio
Published: May 2009

Operating of rotating machinery with a rotor crack is a risk condition, since the rotor crack grows gradually and may fail causing a catastrophic accident. Therefore, it is very important to detect the occurrence of a crack on rotating machinery in early stages. The authors have used the simple two-degree-of-freedom cracked rotor model, and investigated the usage of periodic excitation for the detection of the rotor crack. This paper constructs a finite element rotor model with breathing crack element, and performs the numerical investigation. The dynamic responses of a cracked rotor system under applied periodical external excitation are investigated. The occurrences of various kinds of nonlinear sub-resonances are observed numerically, and the dynamical characteristics of these sub-resonances are clarified. The influences of the position and depth of the crack are clarified. Furthermore, these sub-resonances due to crack are observed in the experiment. This result made us enable to detect the occurrence of a rotor crack.