bluuebunny/crossref_metadata_2025 huggingface dataset:
Metrics-Based Sustainability Evaluation of Manufacturing Technologies: Surface Coating Case Study
Authors: Yang Q. Z. , Chua B. H.
Published: July 2010

Sustainability evaluation of manufacturing technologies is a vital part of decision process in sustainable manufacturing, particularly for decisions on transfer/adoption of new sustainable manufacturing innovations. This paper highlights a study on metrics-based sustainability evaluation of technologies in manufacturing, with emphasis on the technical, economical and environmental sustainability assessments. On the basis of three types of sustainability evaluation metrics proposed in this paper, our study integrates technology assessment, cost analysis and environmental evaluation to support decision-making for selection of sustainable manufacturing processes. Case studies about sol-gel coating and powder coating are explored in the paper to test the proposed sustainability evaluation methods and metrics. The assessment results provide quantitative justifications used in technology transfer of the new sol-gel coating innovations. The results also help potential technology adopters to reduce their implementation risks of the sol-gel coating process in automotive decorative applications.
Influence of Power Conditioning on the Optimization of Energy Harvesting Systems
Authors: Burrow Stephen G. , Clare Lindsay R.
Published: July 2010

Energy harvesting systems have components in both mechanical and electrical domains and in order to optimize the design of the overall system, the effect of practical electrical power conditioning sub-systems on the mechanical operation of the harvester must be taken into account. From basic considerations of a linear energy harvester it is shown that, for optimum mass displacement, the effective load resistance presented to the harvester by the power conditioning circuitry should be equal to or less than the load resistance at the peak power point. Further consideration reveals that peak power per volume may occur at an operating point different to that at which maximum power is achieved. The commonly available building blocks of the power conditioning system have characteristics that make it impossible to operate the harvester in a stable manner in the optimum region, and more complex techniques of maximum power tracking may consume excessive quiescent power and are only valid if maximum power is required at all times. The discussion is illustrated by numerical simulations. Finally a converter topology is described and realized, using discrete components, that goes some way to addressing these issues.
Evaluation of Component Mode Synthesis Methods for the Detection of Modal Interaction Through Rotor Stator Contacts
Authors: Batailly Alain , Legrand Mathias , Cartraud Patrice , Pierre Christophe , Lombard Jean-Pierre
Published: July 2010

The study of interactions through direct contact between bladetips and outer casings in modern turbomachines may be very time-consuming when the classical finite element method is used. The construction of reduced-order models using component mode synthesis (CMS) methods generally allows for dramatic increase in computational efficiency and may be used in order to improve the knowledge over these interaction phenomena. Among the available approaches, both a fixed-interface method and a free-interface method are considered here in an original manner to reduce the size of a realistic two-dimensional model. The equations of motion are solved using an explicit time integration scheme with the Lagrange multiplier method where friction is accounted for. This method offers energy momentum conserving which is a critical point to ensure the convergence of the algorithm. Moreover, it is shown that even in a non-linear framework the reduced-order models converge to the finite element solution as the number of modes included in the models increases. Considering the fixed-interface method of Craig-Bampton (CB) and the free-interface method of Craig-Chang-Martinez (CCM), it is shown that a method with fast displacement convergence may be less efficient in terms of motion convergence.
Backstepping Boundary Control for Unstable Second-Order Hyperbolic PDEs and Trajectory Tracking
Authors: Vatankhah Ramin , Abediny Mohammad , Sadeghian Hoda , Alasty Aria
Published: July 2010

In this paper, a problem of boundary feedback stabilization of second order hyperbolic partial differential equations (PDEs) is considered. These equations serve as a model for physical phenomena such as oscillatory systems like strings and beams. The controllers are designed using a backstepping method, which has been recently developed for parabolic PDEs. With the integral transformation and boundary feedback the unstable PDE is converted into a system which is stable in sense of Lyapunov. Then taylorian expansion is used to achieve the goal of trajectory tracking. It means design a boundary controller such that output of the system follows an arbitrary map. The designs are illustrated with simulations.
An Environmental Cognition Method Based on 3D Laser Radar
Authors: Gao Mingchen , Chen Weihai , Liu Jingmeng , Chen XiaoQi
Published: July 2010

This paper presents normal vector clustering method for environmental cognition using 3D laser radar. With the special design of 3D laser radar, accurate 3D depth of field data can be obtained. The proposed method acts on facet-unit, which is a description of the basic unit of 3D laser data. The novel method, which significantly reduces the amount of computation and improves the computational speed, is able to efficiently distinguish different flats in the 3D space. An embedded system is adopted as the platform for data processing and visualization. TinyGL is implemented on Qt-embedded to enhance the performance of environment map reconstruction and visualization. Experimental results validate the effectiveness of the 3D laser radar and cognition method developed.
On Converting Any One-Step Method to a Variational Integrator of the Same Order
Authors: Patrick George W. , Cuell Charles , Spiteri Raymond J. , Zhang William
Published: July 2010

In the formalism of constrained mechanics, such as that which underlies the SHAKE and RATTLE methods of molecular dynamics, we present an algorithm to convert any one-step integration method to a variational integrator of the same order. The one-step method is arbitrary, and the conversion can be automated, resulting in a powerful and flexible approach to the generation of novel variational integrators.
An Investigation of the Productivity Difference in Mechanical Embodiment Design Between Face-to-Face and Threaded Online Collaboration
Authors: Zheng Jing , Jakiela Mark J.
Published: July 2010

The threaded online, also known as “forum,” collaboration method is widely used by open source software projects. As open source and Crowdsourcing [3] design approaches gain attention, there is a need to explore whether the threaded online method would compete with the more traditional method, face to face, in mechanical engineering design in terms of productivity. Our experiment shows that with a suitably sized challenge, the threaded online method does generate about equal productivity as the face-to-face method. However, the participation rates are lower in the threaded online method and the participants’ satisfaction with the experience was also less. This suggests that additional communication mechanisms are needed to facilitate the threaded online method, and management mechanisms should be imposed. We also identified two phenomena that warrant further investigation. The first is what we call “inertia loafing.” Enthusiasm among online community members is fragile. A small drop in satisfaction level can cause many to become unwilling to participate. The second is that an online community tends to have two kinds of members: “players” who are responsible for most content creation; and “cheer leaders” who provide feedback or provide an assisting function.
Optimal Control for a Pitcher’s Motion Modeled as Constrained Mechanical System
Authors: Ober-Blo¨baum Sina , Timmermann Julia
Published: July 2010

In this contribution, a recently developed optimal control method for constrained mechanical systems is applied to determine optimal motions and muscle force evolutions for a pitcher’s arm. The method is based on a discrete constrained version of the Lagrange-d’Alembert principle leading to structure preserving time-stepping equations. A reduction technique is used to derive the nonlinear equality constraints for the minimization of a given objective function. Different multi-body models for the pitcher’s arm are investigated and compared with respect to the motion itself, the control effort, the pitch velocity, and the pitch duration time. In particular, the use of a muscle model allows for an identification of limits on the maximal forces that ensure more realistic optimal pitch motions.
Approximate Multi-Objective Optimization of Medical Foot Support: Case of 3D Shape Optimization
Authors: Miyake Shin-ichiro , Nakao Suguru , Arakawa Masao
Published: July 2010

Splayfoot seems not serious diseases. However, it cause fatigue in the daily life. In that sense, if we can solve these problems it might support daily life much comfortable especially for elder people. To support splayfoot, there are some commercial ones. But they just add small amount of support and not made up for each person. Besides, when the height of support is not suitable for patients, it sometimes makes situation worse. We have tried it and measured by using myoelectric potential measurements, and see differences of three patients. Even if we use the same commercial support its effectiveness differs to each other and sometimes it makes worse. Physical therapists make foot support for each patient but they make them owing to their experience. There are studies on the positions of bone of foot and its portrait of the desired positions has been reported by medical doctors. One of them is called Mizuno standard [1]. In the previous study, we tried to design foot support aiming to make portrait of this standard in vertical space. For that purpose, we used approximate multi-objective optimization using Radial Basis Function network. For validation, we used electromyography again. As a result the foot support by the proposed method showed the maximum reduction in integral of myoelectric. However, in the previous study [2], we only used two design variables, and we have only designed vertical phase. Therefore, we have not completely designed the support. In this study, we use 3D spline expression to make support, and try to design 3D shape of support. In validation, the results of approximate multi-objective optimization show the best reduction in integral of myoelectric, and show the effectiveness of the proposed method.
Adaptive Sliding Mode Control for Coordinated Motion of Free-Floating Space Manipulators Based on Filtering Technique
Authors: Guo Yishen , Chen Li
Published: July 2010

The adaptive sliding mode control problem of coordinated motion of a free-floating space manipulator with uncertain inertial parameters is discussed. Firstly, with the Lagrangian formulation and the relationship of the system linear momentum conversation, the dynamic equation of a free-floating space manipulator is derived. Based on the above results, a lowpass is fixed at the end of the output of the adaptive sliding mode controller, and then the control scheme of coordinated motion between the base attitude and the joints of the free-floating space manipulator is developed. This proposed control scheme can eliminate the effect of uncertain inertial parameters on the system, filter the high-frequency vibration signals of the output of the adaptive sliding mode controller efficiently, and reduce the vibration caused by the movement of the space manipulator to control the space manipulator to complete the desired motion. Lastly, the simulation results verify the effectiveness of the proposed control scheme.
Extreme Filtering of Rapid Energy Deposition and Its Multiscale Implications
Authors: Lambrakos S. G. , Michopoulos J. G.
Published: July 2010

The present paper focuses on rapid energy deposition processes, where there is extremely strong filtering of spatial and temporal structure within the associated diffusion pattern. This strong filtering tends to establish conditions where reconstruction of detailed features of the energy source using data-driven inverse analysis is not well posed. These strong filtering conditions imply that information that is available concerning the coupling of energy into a spatial region of interest from the site of surface deposition will be difficult to correlate with experimental observations of the associated energy diffusion pattern. The analysis and simulations imply that rapid energy deposition should be characterized by two distinctly separate scales for both spatial and temporal structures. Accordingly, the inverse rapid energy deposition problem requires a formulation with respect to system parameterization that is in terms of two separate sets of parameters. One represents the energy source characteristics on spatial and temporal scales commensurate with that of thermal diffusivity within the material, and the other represents energy source characteristics on spatial and temporal scales commensurate with those of surface phenomena.
An Evaluation Index for Estimating Defeaturing-Induced Impacts on Finite Element Analysis
Authors: Tang Jianguo , Gao Shuming , Lin Hongwei , Liu Yusheng
Published: July 2010

Defeaturing is a popular CAD/CAE simplification technique. However, defeaturing inevitably leads to errors that can not be effectively evaluated yet during a FE (Finite Element) analysis. In this paper, a novel evaluation index based on the reciprocal theorem is proposed to effectively and efficiently estimate defeaturing-induced impacts on FE analysis. Instead of using the difference of strain energy, the proposed evaluation index uses the difference of work to quantify the defeaturing-induced impacts on FE analysis so that it is not only effective but also can be efficiently calculated. In order for an efficient calculation of the evaluation index, a practical evaluation index is further derived from the proposed theoretical index, and its calculation method is given. The practical evaluation index has been applied to FE static computation of linear elastic structures. Therefore, we are able to adapt the simplification of a model according to a desired accuracy of the analysis results.
Periodic Solutions for Coupled Van Der Pol Oscillators of Two-Degree-of-Freedom Solved by Homotopy Analysis Method
Authors: Zhang Wei , Qian Youhua , Wang Qian
Published: July 2010

Innumerable engineering problems can be described by multi-degree-of-freedom (MDOF) nonlinear dynamical systems. The theoretical modelling of such systems is often governed by a set of coupled second-order differential equations. Albeit that it is extremely difficult to find their exact solutions, the research efforts are mainly concentrated on the approximate analytical solutions. The homotopy analysis method (HAM) is a useful analytic technique for solving nonlinear dynamical systems and the method is independent on the presence of small parameters in the governing equations. More importantly, unlike classical perturbation technique, it provides a simple way to ensure the convergence of solution series by means of an auxiliary parameter ħ. In this paper, the HAM is presented to establish the analytical approximate periodic solutions for two-degree-of-freedom coupled van der Pol oscillators. In addition, comparisons are conducted between the results obtained by the HAM and the numerical integration (i.e. Runge-Kutta) method. It is shown that the higher-order analytical solutions of the HAM agree well with the numerical integration solutions, even if time t progresses to a certain large domain in the time history responses.
Introduction of Model-Based Identification Methods Applied to Rotating Machinery of E´lectricite´ de France
Authors: Ricci Roberto , Pennacchi Paolo , Meissonnier Franck , Nistor Ionel , Stoisser Carlo Maria , Voinis Philippe
Published: July 2010

This paper describes the requirements and the main features of a research project that plans to introduce model-based diagnostic methods for the analysis of dynamic behavior of the rotating machinery of EDF – E´lectricite´ de France. The aim is to insure safe and security in the operating conditions and to provide reliability in the energy supply, by reducing the out-of-service periods and the cost of maintenance, and by improving the lifetime assessment of components of rotating machinery. Model-based method is described in detail and the relevant methods for tuning the models are also introduced.
Knowledge Management and Customised 3D Modelling to Improve Prosthesis Design
Authors: Gabbiadini Stella , Colombo Giorgio , Facoetti Giancarlo , Rizzi Caterina
Published: July 2010

This paper presents a new approach to design lower limb prosthesis focusing the attention on geometrical model issues. The new design approach has been developed within national and international research projects and, at present, “ad hoc” tools to carry out specific tasks are under development. Within this context, an important role is played by product and process knowledge and by specific CAD tools to design the most critical component, the socket. The paper discusses acquisition and formalisation of the knowledge related to the prosthesis design, with particular attention to the socket, and presents main features of a CAD tool specifically intended for this highly customised component.
Computer Aided Style Design System Based on Highlight Lines
Authors: Yano Sakiko , Aoyama Hideki
Published: July 2010

Free-form surfaces are useful for modeling the external shape of industrial products but designers are still facing difficulty in designing high-quality aesthetic surfaces because commercial CAD systems currently available lack the required performance to support their design work. This has therefore led to the increasing need for design-aiding modeling systems to enhance the efficiency of high quality surface design processes. This paper proposes a method of redesigning aesthetic surface shapes by controlling unit normal vectors on the surface and discusses a fundamental system constructed based on the proposed technique. Attempts were also made to construct the required character lines using the proposed technique. Additionally, the validity of the proposed technique was also verified. In the surface evaluation stage of existing product design processes, the highlight-check method using highlight lines on the surface of a model is the most common and popular evaluation method even though methods using curvature and isophote have been proposed. With this method, the unit normal vectors on the surface are controlled by highlight lines. A highlight line is defined as a curve which consists of points with a constant angle to the right reflective direction when a beam shines on an arbitrary point on a surface. With this highlight-check system, highlight lines are displayed on the screen and evaluated by the designer. When highlight lines are faulty or those required by the designer cannot be obtained, the designer just needs to enter the required highlight lines manually by drawing with a pen tablet on LCD interactive display to improve surface quality. Usually, the system takes input highlight line information as unit normal vector information, and constructs the required surface shape using that information.
A Matlab/Simulink Model of the Inner Ear Angular Accelerometers Sensors
Authors: Selva Pierre , Gourinat Yves , Morlier Joseph
Published: July 2010

In order to keep tabs on the position and motion of our body in space, nature has given us a fascinating and very ingenious organ, the inner ear. Each inner ear includes five biological sensors — three angular and two linear accelerometers — which provide the body with the ability to sense angular and linear motion of the head with respect to inertial space. The aim of this paper is to present a mechanical model of the semicircular canals — which behave as angular accelerometers — in a specific kinematic environment. This model, implemented in Matlab/Simulink, simulates the rotary chair testing, which is one of the usual tests carried out during a diagnosis of the vestibular system. This model also allows to simulate several head rotations, and at the same time to show the state — excited or inhibited — of each angular sensors. Therefore, the developed model can be used as a learning and demonstrating tool either in the medicine field to understand the behavior of the sensors during any kind of motion or in the aeronautical field to relate the inner ear functioning to some sensory illusions. In addition, the first results also show the influence of the non-orthogonality of the canals on the sensors stimulation.
Factor Analysis of Head-Up Display Presentation Images
Authors: Smith Shana , Fu Shih-Hang
Published: July 2010

This study explored the relationships between drivers and HUD presentation image designs using Kansei engineering. Kansei words were associated with physical design elements. Initially, existing HUD presentation images were collected. Next, major design elements were extracted from the images. Then, new images were generated, based upon the major design elements. A questionnaire and user experiment was conducted. Finally, the results were analyzed using factor analysis. Thirty-six pairs of Kansei words were reduced and grouped into 5 groups of Kansei words. The final 5 groups of Kansei words can be used to clearly describe the HUD presentation images. The method can be used as a reference for future HUD image design tasks.
Precision Motion Control of Tubular Linear Motors With Neural Networks and Compact Genetic Algorithms
Authors: Cupertino Francesco , Naso David , Turchiano Biagio
Published: July 2010

This paper describes a control system for a tubular synchronous linear motor based on a combination of a linear PID controller and a nonlinear neural network. The nonlinear part of the controller is introduced to progressively augment the tracking performance of the system and is trained online by a compact GA. In particular, we implement a variant of a known compact GA that well lends itself to practical implementations in low capacity microcontrollers, thanks to its reduced memory requirements and better distributed computational loads. The potential of the proposed approach is assessed by means of experimental tests using a tubular linear synchronous motor prototype. The control system obtained through genetic search outperforms alternative schemes obtained with linear design techniques in terms of robustness to payload mass change and sensitivity to static friction.
Intermittent Chaotic Dynamics of Rail Axle Supported by Roller Bearings
Authors: Harsha S. P. , Nataraj C. ‘Nat’
Published: July 2010

In this paper, intermittent chaotic analysis of high speed rail axle supported by roller bearings has been analyzed. In the analytical formulation, the contacts between rolling elements and races are considered as nonlinear springs, whose stiffness values are obtained by using Hertzian elastic contact deformation theory. The results show the appearance of instability and chaos in the dynamic response as the speed of the axle-bearing system is changed. Period doubling and mechanism of intermittency have been observed which lead to chaos. The appearance of regions of periodic, sub-harmonic and chaotic behavior is seen to be strongly dependent on the radial clearance. Poincare´ maps, time response and frequency spectra are used to elucidate and to illustrate the diversity of the system behavior.
PB-Spline Hybrid Surface Fitting Technique
Authors: Carminelli Antonio , Catania Giuseppe
Published: July 2010

This work considers the fitting of data points organized in a rectangular array to parametric spline surfaces. Point Based (PB) splines, a generalization of tensor product splines, are adopted. The basic idea of this paper is to fit large scale data with a tensorial B-spline surface and to refine the surface until a specified tolerance is met. Since some isolated domains exceeding tolerance may result, detail features on these domains are modeled by a tensorial B-spline basis with a finer resolution, superimposed by employing the PB-spline approach. The present method leads to an efficient model of free form surfaces, since both large scale data and local geometrical details can be efficiently fitted. Two application examples are presented. The first one concerns the fitting of a set of data points sampled from an interior car trim with a central geometrical detail. The second one refers to the modification of the tensorial B-spline surface representation of a mould in order to create a local adjustment. Considerations regarding strengths and limits of the approach then follow.
Estimation of Applied Forces on a Six-Degrees-of-Freedom Motion Platform
Authors: Shiiba Taichi , Sasaki Shoichi , Takahashi Naoki
Published: July 2010

In this paper, the development of a small-sized 6-degrees-of-freedom (DOF) motion platform is reported, and the estimation method of applied force to the output plate of the motion platform based on the inverse multibody dynamic analysis is proposed. The developed motion platform is actuated by six brushless DC servomotors mounted on the base plate. When a force is applied on the output plate of the motion platform, the output torque of the actuator is changed. The motor torque can be evaluated by measuring the motor winding current. In our approach, the motor torque is also calculated on the assumption that no applied force is working to the motion platform the inverse multibody dynamic analysis of the motion platform. By comparing the calculated motor torque with actually measured value, the effect of the applied force would be estimated. In order to enhance the accuracy of estimation, the effect of frictions in mechanical elements of the 6-DOF motion platform should be considered. We experimentally evaluated the characteristics of the friction in the gear head of the brushless DC servomotor, and the result was used for the inverse multibody dynamic analysis. This estimation approach was examined in various conditions of the motion platform, and the results are discussed in this paper.
Analysis of Independently Rotating Wheel System Using Multibody Dynamics Approach
Authors: Sugiyama Hiroyuki , Matsumura Ryosuke , Suda Yoshihiro , Ezaki Hideaki
Published: July 2010

In this investigation, dynamic characteristics of independently rotating wheel systems (IRW) are discussed. To this end, a multibody IRW model is developed using the method of velocity transformation. The linear stability analysis of a two-axle IRW truck is first performed, and the hunting stability and vibration characteristics of IRW truck are investigated and the results are compared with those obtained using the multibody dynamics model. Good agreements are obtained in hunting frequencies and critical speed. It is shown using the linear IRW equations that since a constant forward speed is assumed for IRW, the longitudinal slip can occurs due to the change in the wheel rolling radii resulting from the lateral displacement. This leads to longitudinal creep forces even in the case of IRW and it contributes to a weak coupling of the lateral and yaw motion of IRW. Furthermore, it is observed in several numerical examples that, due to small self-centering forces of IRW, continuous flange contact occurs on tangent track, while in curve negotiation flange contacts on outer wheel of the front axle as well as that on inner wheel of the rear axle occurs. It is presented that the received wisdom that longitudinal creep forces of IRW ideally equal to zero is contradicted in tight curve negotiation and special care need to be exercised when a simplified IRW model is used.
Stable 6-DOF Haptic Rendering With Inner Sphere Trees
Authors: Weller Rene , Zachmann Gabriel
Published: July 2010

We present a novel geometric data structure for approximate collision detection at haptic rates between rigid objects. Our data structure, which we call inner sphere trees, supports both proximity queries and the penetration volume; the latter is related to the water displacement of the overlapping region and, thus, corresponds to a physically motivated force. Moreover, we present a multi-threaded version of the penetration volume computation for time-critical haptic rendering that is based on separation lists and the novel notion of expected overlapping volumes. Finally, we show how to use the penetration volume to compute continuous contact forces and torques that enable a stable rendering of 6-DOF penalty-based distributed contacts. The main idea of our new data structure is to bound the object from the inside with a bounding volume hierarchy, which can be built based on dense sphere packings. In order to construct an efficient hierarchy, we propose to use an AI clustering algorithm, which we extend and adapt here. The results show performance at haptic rates both for proximity and penetration volume queries for models consisting of hundreds of thousands of polygons.
Matrix-Based Product Representation to Support Flexible Multibody Simulation
Authors: Kain Andreas , Gaag Andreas , Lindemann Udo , Roesch Oliver , Bonin Thomas , Zaeh Michael F.
Published: July 2010

The structural behavior of machine tools has a large influence on the achievable tolerances. Vibrations of a machine tool structure result in poor surface finish. Small modifications in highly dynamic machine tools on the component level may cause unpredictable changes in overall machine tool behavior. A multibody system (MBS) is able to predict product kinematics and dynamics. The authors propose a matrix based approach to combine solution neutral system representation, solution specific product representation, and product behavior in order to improve system comprehension. It comprises knowledge and experience that occur along the whole product lifecycle of machine tools and can be utilized to support preprocessing and validation of flexible multibody systems (fMBS). A case study carried out together with a major industrial partner illustrates the suggested approach. This paper exemplifies the matrix based product representation at composing a flexible multibody simulation of a highly dynamic linear gear shaping machine. Preparation and evaluation of the product representation enhances inter domain root cause analysis as well as preprocessing and validation of flexible multibody models.
PB-Spline Finite Element Shell Modeling and Refinement Technique
Authors: Carminelli Antonio , Catania Giuseppe
Published: July 2010

This paper presents a Point Based (PB) spline degenerate shell finite element model to analyze the behavior of thin and moderately thick-walled structures. Complex shapes are modeled with several B-spline patches assembled as in conventional finite element technique. The refinement of the solution is carried out by superimposing a tensorial set of B-spline functions on a patch and employing the PB-spline generalization. The domains for the numerical integration are defined by making use of the retained tensorial framework. Some numerical examples are presented. Considerations regarding strengths and limits of the approach then follow.
Study of the Relationship Between Parameters and Effectiveness of Essential Nonlinear Absorber
Authors: Simi Tang , Zhu Shijian , Lou Jingjun
Published: July 2010

The two degree-of-freedom (dof) system consisting of a linear oscillator coupled with a essential nonlinear absorber is studied, which is under periodic excitation. Applying harmonic balance technique, we derive a set of modulation equation that is directly amenable to characteristic of amplitude-frequency of the system. Conclusion can be summarized: With some parameters, the absorber performs effectively over a broad range of frequency; but the amplitude of linear oscillator may jump suddenly for the change of parameters. The effectiveness of absorber is also affected by the forcing, that is different from classical absorber. The relationship between parameters and effectiveness of essential nonlinear absorber are determined and the parameter region seems to comply with some rules.
Coupling OCREC Contact Code With ADAMS: Simulations of One Coach at 130mph
Authors: Pascal J. P. , Berger J. , Bondon F. , Clerc C. , Teppe S.
Published: July 2010

This paper presents the Online Calculation of Railway Elastic Contacts (OCREC), a dynamic railway calculation tool based on an advanced contact kernel, and its coupling with the MSC ADAMS multi-body commercial software. The OCREC contact kernel is used as a subroutine of multi-body codes in order to calculate contact forces between wheelsets and rails. The OCREC method is “online” as it not only redefines new contact parameters at each time step but also determines all simultaneous contacts on each wheel as allowed by Hertz Elasticity theory. From the normal forces and relative velocities given by the Hertz theory, Tangential Forces are calculated using Kalker’s FASTSIM (modified for elliptical pressure distribution). After a description of the OCREC theory, the paper presents the linkage between OCREC and MSC ADAMS software. OCREC calculates contact forces within a Frenet frame (oxyz) following the track layout where ox is tangent to the track; oy is horizontal and oz normal to oxy. As ADAMS calculates inside a different frame, and as it has no built-in track system, it was necessary to develop a program capable of connecting 3 different frames: the ‘dummy’ track frame, the Frenet frame and the fixed ADAMS frame. Note that the ‘dummy’ frame is directly calculated from railway track curvature measurements recorded in so-called ‘space curves’. The OCREC ADAMS link is first validated by a bogie rolling on a dummy track. With the equations of the OCRECYM code established directly within the “dummy” frame, the OCREC-ADAMS results are compared to a specific OCRECYM validation code. Then, the results from an actual railway case are presented: behavior of one coach is calculated on a real measured track including curves and defaults. During the following step, the OCREC-ADAMS results are compared to OCRECYM results. After some model updating for adjustment to physical properties of elastic joints (helicoidal springs), a good correlation is obtained between the codes. The analysis of the different force and displacement components proves this kind of numerical tool’s capabilities of assessing the railway vehicle’s dynamic behavior. Especially, the Y/Q safety ratio is well calculated. Thus, the OCREC contact kernel, which is powerful for complex contact topologies such as conformal contacts, and necessary for high speed safety calculation, can be used as a subroutine of standard multi-body software, giving it high capabilities for dynamic railway calculation.
Experimental Evaluation of Nonlinear Dynamics and Coupled Motions in a Pantograph
Authors: Hare`ll Poznic´ Pia , Jerrelind Jenny , Drugge Lars
Published: July 2010

Continuous electric power supply, which is transferred from the contact wire to the train through a pantograph mechanism, is a necessity for a train to function satisfactory. Since various sources of nonlinearities are present, such as friction in the pantograph suspensions and impacts in the subsystems and at the excitation, there is a possibility of nonlinear dynamic behaviour. The aim of this work is to experimentally investigate the dynamic behaviour of a commercial pantograph to verify if nonlinear behaviour and coupling effects can occur. A test rig has been built that has the ability to simulate both the horizontal and vertical excitation generated by the contact wire. Measurements have been performed for sinusoidal input signals both in horizontal and vertical directions. Harmonic and subharmonic motions as well as irregular behaviour are shown to exist in the system. The results show that the pantograph’s rotational degree of freedom, friction in the suspension systems and the nonlinear stiffness play an important role for the dynamic behaviour of the system and are therefore crucial to include when creating mathematical models of the system.
Multiple Impact Based Energy Absorption
Authors: Gharib Mohamed , Celik Ahmet , Hurmuzlu Yildirim
Published: July 2010

In this paper, we numerically solve the elastic multiple impact problem in a linear chain of balls using the impulse-momentum and the Hertz contact theory based methods. The first method depends on a parameter called the impulse correlation ratio (ICR), while the latter one depends on the material properties and geometries of the colliding bodies. We compared the post impact velocities from the two methods and we found that the two methods yield similar solutions for elastic collisions. Then, we develop an energy absorption scheme using an arrangement of balls with different sizes. The impulse momentum method is used with the aid of the Hertz method to obtain the ICRs. We use numerical analysis to demonstrate that one can significantly improve the energy absorption by placing small balls in specific locations in a linear chain of particles.
Numerical Simulation of New Generation Non-Pneumatic Tire (TWEEL™) and Sand
Authors: Ma Jianfeng , Kolla Avinash , Summers Joshua D. , Joseph Paul F. , Blouin Vincent Y. , Biggers Sherrill
Published: July 2010

In order to have a better understanding of the performance of non-pneumatic tires (Tweel™) on soil and provide information for further optimization of this Tweel™, we model and simulate the interaction between Tweel™ and soil using finite element method (FEM). In this paper, the model of the Tweel™ is described in detail. The Tweel™ is treated as a deformable body. The Drucker-Prager/Cap plasticity constitutive law with hardening is employed to model sand. The material properties of Lebanon sand found in New Hampshire that has a complete set of material properties in the literature is used. Numerical results show deformation of sand and Tweel™. The stress distributions in sand, Tweel™, and along the interface between them are also presented. We next illustrate how this interaction model can be used to develop new tractive solutions for lunar exploration and terrestrial travel over dry soil.
Nonlinear Fractional Derivative Stress-Strain Relations for Polymer Gels Based on the Generalized Maxwell Model
Authors: Fukunaga Masataka , Shimizu Nobuyuki
Published: July 2010

In this paper, we formulate two nonlinear stress-strain relations including memory effect in the dynamical behavior of gels that are the kind of viscoelastic materials. The basic assumption of the model is made that the gels consist of blobs of high polymers. Hereditary response of blobs to the stress determines the average stress-strain relation of the material. Two stress-strain relations are derived for different models of gels. These stress-strain relations are compared with the fractional derivative version of Lodge’s rubber-like liquids and the empirical nonlinear fractional derivative model proposed by Fukunaga et. al. at FDA08.
Using Domain Specific Languages to Capture Design Synthesis Knowledge for Model-Based Systems Engineering
Authors: Kerzhner Aleksandr A. , Paredis Christiaan J. J.
Published: July 2010

Design synthesis is a fundamental engineering task that involves the generation of a structural specification from a desired functional specification. Although the use of computer tools is common throughout the design process, design synthesis is often a task left to the designer. Formally capturing design synthesis knowledge in models and applying computational synthesis may result in better exploration of the design space and eliminate repetitive design tasks. In this paper, a graph-based framework for capturing and combining design synthesis knowledge is presented for scenarios involving the composition of well defined components into larger systems. This approach fits in the context of Model-Based Systems Engineering where a variety of formal models are used to represent knowledge about a system. This approach uses the Systems Modeling Language developed by The Object Management Group (OMG SysML™) to define both models of possible components and possible system architectures. The framework is illustrated by combining it with an evolutionary algorithm and applying it to an example problem of hydraulic circuit synthesis.
Reduced-Order Modeling of Energy Harvesters
Authors: Seuaciuc-Oso´rio Thiago , Daqaq Mohammed F.
Published: July 2010

This work addresses the accuracy and convergence of reduced-order models (ROMs) of energy harvesters. Two types of energy harvesters are considered, a magnetostrictive rod in axial vibrations and a piezoelectric cantilever beam in traverse oscillations. The partial differential equations (PDEs) and associated boundary conditions governing the motion of these harvesters are obtained. The eigenvalue problem is then solved for the exact eigenvalues and modeshapes. Furthermore, an exact expression for the steady-sate output power is attained by direct solution of the PDEs. Subsequently, the results are compared to a ROM attained following the Rayleigh-Ritz procedure. It is observed that the eigenvalues and output power near the first resonance frequency are more accurate and has a much faster convergence to the exact solution for the piezoelectric cantilever beam. In addition, it is shown that the convergence is governed by two dimensionless constants, one that is related to the electromechanical coupling and the other to the ratio between the time constant of the mechanical oscillator and the harvesting circuit. Using these results, conclusions are drawn with regards to the design values for which the common single-mode ROM is accurate.
Estimation of the Hankel Singular Values of Fractional-Order Systems
Authors: Adams Jay L. , Veillette Robert J. , Hartley Tom T.
Published: July 2010

This paper applies the Rayleigh-Ritz method to approximating the Hankel singular values of fractional-order systems. The algorithm is presented, and estimates of the first ten Hankel singular values of G(s) = 1/(sq+1) for several values of q ∈ (0, 1] are given. The estimates are computed by restricting the operator domain to a finite-dimensional space. The Hankel-norm estimates are found to be within 15% of the actual values for all q ∈ (0, 1].
Energy Concern in Biomolecular Simulations Involving Transitions From Coarse to Finer Grain Models
Authors: Anderson Kurt S. , Poursina Mohammad
Published: July 2010

Generating self-adjusting multiscale models is necessary to analyze the complex behavior of biomolecular systems in an accurate, yet timely manner. The model transitions are achieved by effectively imposing or releasing certain systems constraints from a fine scale model to a reduced order model or vice versa. In the process of model reduction of such molecular systems, naturally existing higher modes are frozen out in the modeling because the internal metric had previously indicated these modes of motion as less relevant. In the transition from a coarse model back to a finer one, the appropriate amount of energy must be put back to the system. Herein, the non-uniqueness or even the presence of infinite number of solutions in this transition is addressed. Optimization and non-optimization methods are proposed to arrive at the finite number of solutions.
A New Event Model for PML
Authors: Anderl Reiner , Raßler Jochen , Rollmann Thomas
Published: July 2010

Processes are very important for the success within many business fields. They define the proper application of methods, technologies and company structures in order to reach business goals. Not only manufacturing processes have to be defined from the start point to their end, also other processes like product development processes need a proper description to gain success. For example in automotive industries complex product development processes are necessary and defined prior to product development. This paper is an advancement of PML — the object-oriented Process Modeling Language, introduced in earlier publications. A new Event Model for PML is introduced and the association to the resources model and the product data model is described. The concepts are shown by some examples to illustrate their usage.
A Modeling Approach for Simulating Heat Dissipation From Actuators and Electronic Components Embedded in Thermally Conducting Polymers
Authors: Bejgerowski Wojciech , Gupta Satyandra K. , Bruck Hugh A.
Published: July 2010

Thermally conductive polymer composites allow for creating multi-functional structures that offer both anchoring points for the embedded actuators as well as heat dissipation functions. This paper focuses on understanding the heat dissipation function through a coupled modeling of polymer melt flow to obtain fiber orientations along with orthotropic thermal conductivities is presented to simulate the dissipation of heat generated by an electrical component embedded in both unfilled and filled polymer structures. The performed simulations indicate that the gain in heat dissipation when using commercially available thermally conductive polymers results in 40% reduction in the operating temperature of the embedded electronic component. In the case of an embedded actuator, such as a pager motor, this is expected to significantly enhance performance. The orthotropic thermal conductivity resulting from fiber orientation was found to not significantly influence the heat dissipation function of the structural geometries that were studied in this paper. Therefore, in such cases the computational effort involved in modeling process-dependant orthotropic thermal conductivities can be omitted during the design of filled polymer structures with embedded actuators. Validation of the model was obtained through comparison of simulation predictions with experimental results for a simple embedded ceramic resistor and a more complex embedded motor in a model structure. We also found that increasing the thermal conductivity beyond the value of 2 W/m-K had very little impact on the heat dissipation function. This work establishes the feasibility of creating multi-functional structures from filled polymers by embedding actuators to facilitate the miniaturization of devices.
Challenges for Experience Feedback in Engineering Design
Authors: Nerga˚rd Henrik , Larsson Tobias
Published: July 2010

In this paper empirical finding from a study conducted at an aerospace company is compared to theory regarding Experience Feedback (EF), Lessons Learned (LL) and Decision Making (DM). The purpose with the study was to examine how EF within the organization was conducted and what problems and possibilities that was seen. A qualitative approach was taken and interviews and a workshop was conducted. The empirical findings show that EF exist on different levels within the organization but current feedback processes are currently leaning more towards archiving and storing than knowledge sharing and learning. Also passive dissemination approaches are mostly used whereas active dissemination within the correct context is needed The aim with this paper is to discuss issues and empirical findings that should be considered when creating work methods and systems that support learning by EF and LL dissemination.