Research on Parallel Computation Architecture Based on Object Computing Network

A new method of multibody system dynamics, named discrete time transfer matrix method of multibody system (MS-DT-TMM) is developed and widely used in engineering field in recent years. When using this method for the problems of multibody system dynamics, the global dynamics equations of the system are not needed and the orders of involved system matrices are always small. The advance in MS-DT-TMM in recent years has been studied in this paper as following: 1 Discrete time transfer matrix method of rigid-flexible multibody system is developed to study rigid-flexible multibody system dynamics. 2 Mixed method of MS-DT-TMM and finite element method is developed to study rigid-flexible multibody system dynamics. 3 Mixed method of MS-DT-TMM and multibody system dynamics method is developed to study rigid-flexible multibody system dynamics. 4 Riccati discrete time transfer matrix method of multibody system is developed to increase the computation speed and the computation stability. 5 Discrete time transfer matrix method of controlled multibody system is developed to study dynamics of controlled multibody system. Several corresponding numerical examples are done to validate these proposed methods. All this implies that the proposed methods provide a powerful tool for the study of multibody system dynamics.

In large, rigid multibody dynamics problems with friction and contact, encountered for instance in granular flows, one can witness distinctly different system-level dynamics. This contribution concentrates on the case of fluid-like behavior of large multibody dynamics systems such as granular materials, when the system experiences large strains. The results reported herein draw on computer simulation; on the one hand, we solve the Newton-Euler equations of motion, which govern the evolution of multibody dynamics system featuring frictional contact. On the other hand, we solve the Navier-Stokes equations which describe the time evolution of fluids. To demonstrate the similarities and differences between the multibody and fluid dynamics we consider three problems modeled and solved using different methods; (i) a compressibility test; (ii) the classical dam break problem, and (iii) the dam break simulation with an obstacle. These experiments provide insights into conditions under which on can expect similar characteristics from multibody and fluid dynamics systems governed by manifestly different equations of motion and solved by vastly different numerical solution methods. The models and simulation platform used are publicly available and part of an open source code called Chrono. Both the multibody and fluid dynamics simulations are carried out using GPU computing.

Multibody systems in planar motion are modelled as two or more rigid components that are connected and can move relative to each other. The dynamics of such multibody systems in planar motion in a central gravitational force field is analysed. The equations of motion of the system include the equations for the orbital motion of the bodies, the orientation (attitude) of the assembly, and the relative orientation (shape) of the bodies with respect to each other. Dynamic coupling between these degrees of freedom gives rise to complex dynamical systems that are usually not integrable. Relative equilibria, corresponding to circular orbits of the multibody system, are obtained. The free dynamics has a symmetry due to a cyclic coordinate. Routh reduction is carried out to eliminate this coordinate and obtain the reduced dynamics. The stability of the relative equilibria is analysed using the Routh stability criterion when it is applicable; an expansion of the Hamiltonian in normal form is used otherwise. We apply the general results to a multibody system consisting of two hinged planar bodies, each modelled as a rigid massless link with a point mass at one end with their other ends connected by a hinge joint. We obtain the relative equilibria of this model, and carry out a stability analysis for the relative equilibria. Numerical simulations using a symplectic integrator are carried out for perturbations to these relative equilibria, to confirm their stability properties.

Data standardization is still an open research field in multibody system (MBS) dynamics, and the lack of a standard neutral data format to encode information about MBS models (topology, geometry, rigid and flexible body data, applied forces, type of analysis, …) hinders the exchange and share of models between users of MBS software. Therefore, the MBS research community should start to address the interoperability needs in this field as soon as possible. This article presents some foundations for that task: the requirements for a neutral data format are presented, the current interoperability state in MBS dynamics is evaluated, and two data modeling technologies (STEP and XML) are compared in order to develop a robust yet easy-to-use neutral data format for multibody systems. An XML-based prototype implementation of such a format is proposed, demonstrating the excellent aptitudes of XML for this task. Finally, guidelines for future standardization of multibody system data are given. In conclusion, both STEP and XML should be combined in the future to solve the interoperability problems in multibody system dynamics in an effective way.

It is an exceptional success when multibody dynamics researchers Multibody System Dynamics journal one of the most highly ranked journals in the last 10 years. In the inaugural issue, Professor Schiehlen wrote an interesting article explaining the roots and perspectives of multibody system dynamics. Professor Shabana also wrote an interesting article to review developments in flexible multibody dynamics. The application possibilities of multibody system dynamics have grown wider and deeper, with many application examples being introduced with multibody techniques in the past 10 years. In this paper, the development of multibody dynamics is briefly reviewed and several applications of multibody dynamics are described according to the author’s research results. Simulation examples are compared to physical experiments, which show reasonableness and accuracy of the multibody formulation applied to real problems. Computer simulations using the absolute nodal coordinate formulation (ANCF) were also compared to physical experiments; therefore, the validity of ANCF for large-displacement and large-deformation problems was shown. Physical experiments for large deformation problems include beam, plate, chain, and strip. Other research topics currently being carried out in the author’s laboratory are also briefly explained.

This text is a classical and complete book on rigid multibody dynamics. Some of the topics covered include: various angular orientation descriptions, including Euler angles, Bryan angles, and Euler-Rodrigues parameters; quaternion algebra; virtual power; graph theory; and vibration analysis of chains of bodies. The textbook is an excellent reference, containing valuable material for graduate students and researchers. The chapters have an average of six example and problem sets, for which solutions are provided. Aside from the lack of problems, the book can easily be used as a text for a graduate course on the dynamics of rigid multibody systems.

The principle of virtual work is used to derive the Euler-Lagrange equations of motion in order to describe the dynamics of multibody android systems. The constrained variational equations are in fact differential-algebraic equations of high index and are cast as ordinary differential equations through differentiation of the constraint equations. The integration routine LSODAR and the fourth-order Runge-Kutta method are used to compute the generalized coordinates, their time derivatives and the body forces of two android models. The graphs of the constraint forces reveal the whiplash effect on the neck and that the stiffness of both multibody systems is due to large magnitude impulsive forces experienced by many bodies simultaneously.

［1］Zhang Dajun,Liu Youwu,Yun Chao,et al. Flexible multibody system dynamics-finite segment method. Chinese Journal of Mechanical Engineering, 1994,7(2): 156～162 ［2］Huston R l, Passerello C E.Finite element methods-an introduction. New York:Marcel Dekker, 1984 ［3］Huston R L, Liu Youwu. Dynamics of multibody system. Tianjin: publishing House of Tianjin University, 1991 ( in Chinese) ［4］Xie Yiquan, He Fubao. The finite element method in elastic and plastic mechanics. Beijing: Publishing House of Mechanical Industry,1981(in Chinese) ［5］Shan Huizu. Material mechanics. Beijing: Publishing House of National Defence Industry, 1995 ( in Chinese) ［6］Huadong Hydraulic College. Finite element method for problems of elastic mechanics. Beijing: Hydroelectricity Publishing House, 1978( in Chinese)

Professor Dr. Kurt Magnus (1912–2003) would celebrate his 100th birthday on September 8, 2012. That is a reason to remember this internationally renowned scientist in the field of mechanics, particularly gyrodynamics and multibody system dynamics. By him, the science of gyrodynamics had once again a golden age in Germany. He established branches of mechanics, which we call today “multibody system dynamics” and “mechatronics.” Also, he was very well known as the editor-in-chief of the Ingenieur-Archiv (Archive of Applied Mechanics) from 1963 to 1980. In this contribution, his scientific career will be described and his outstanding research work will be acknowledged. From 1966 to 1980, Kurt Magnus was Full Professor of Mechanics at the Munich University of Technology. During this period, the research field of multibody system dynamics became more and more interesting. Therefore, he initiated and chaired the first IUTAM Symposium on Dynamics of Multibody Systems at Munich, August 29–September 3, 1977. Excellent lectures and intensive discussions showed the state-of-the-art and the further potential for research and application. This contribution will remember these early steps of multibody system dynamics.

Multibody system dynamics is already a well developed branch of theoretical, computational and applied mechanics. Thousands of documents can be found in any of the well-known scientific databases. In this work it is demonstrated that multibody system dynamics is built of many thematic communities. Using the Elsevier’s abstract and citation database SCOPUS, a massive amount of data is collected and analyzed with the use of the open source visualization tool Gephi. The information is represented as a large set of nodes with connections to study their graphical distribution and explore geometry and symmetries. A randomized radial symmetry is found in the graphical representation of the collected information. Furthermore, the concept of modularity is used to demonstrate that community structures are present in the field of multibody system dynamics. In particular, twenty-four different thematic communities have been identified. The scientific production of each community is analyzed, which allows to predict its growing rate in the next years. The journals and conference proceedings mainly used by the authors belonging to the community as well as the cooperation between them by country are also analyzed.

The First Joint International Conference on Multibody System Dynamics (IMSD2010), held in May 2010 at the Lappeenranta University of Technology (LUT) in Finland, enabled the international multibody community to meet and exchange information and ideas on the theory and applications of multibody systems. It was sponsored by the ASME (American Society of Mechanical Engineers), IFToMM (International Federation for the Promotion of Mechanism and Machine Science), IUTAM (International Union of Theoretical and Applied Mechanics), KSME (Korean Society of Mechanical Engineers), and JSME (Japan Society of Mechanical Engineers). The conference, attended by 242 participants, featured more than 180 presentations, delivered by representatives of 29 countries. In view of the exceptional works presented and the discussions that followed, which included many of the foremost international researchers in Multibody Dynamics, a selected number of authors were invited to submit manuscripts to the Multibody Systems Dynamics journal where they have undergone a strict peer-review process. This issue of the Multibody Systems Dynamics journal presents six of these papers representing the range of topics addressed by Multibody Dynamics; vehicle dynamics, control and mechatronics, algorithms, integration codes, and software. These manuscripts suggest a trend towards theoretically and computationally challenging applications. We are confident that journal readers will find the contents of this issue informative and valuable in their activities related to multibody systems. We would like to take this opportunity to thank the sponsors, organizers, and all participants of the IMSD2010 conference. The success of this First Joint International Conference on Multibody System Dynamics would not have been possible without

The prediction of transient response of structures, in the form of traveling waves, is very important for controlling the dynamic behavior of structures. It is well known that the standard semi-discrete form of the finite element method is not suitable for predicting the wave propagation, due to the inherent dispersion involved. In this paper, an application of space-time finite element method to the wave propagation problem is discussed. The main concerns in such problems consist of developing a consistent and stable scheme and also of capturing a shock wave, without wiggling. We discuss, at first, a weak form of the wave propagation problem, taking into account the jump condition associated with velocity and stress. A mixed finite element formulation plays an important role in evaluating the velocity explicitly. The application of present formulation to the linear wave equation shows that the present numerical results at the discontinuity give the mean values of jump. In the case of flexural wave propagations in Timoshenko beam, the present method captures the wave front easily rather than the semi-discrete method.

The Technical Committee on Multibody Systems and Nonlinear Dynamics (MSND-TC) of the ASME Design Engineering Division solicits nominations for the D'Alembert Award and the Lyapunov Award. These awards will be presented at the 6th ASME International Conference on Multibody Systems, Nonlinear Dynamics and Control, as part of the ASME 2007 International Design Engineering Technical Conferences to be held in Las Vegas, Nevada, September, 2007.The D'Alembert Award is established to recognize lifelong contributions to the field of multibody system dynamics.The Lyapunov Award is established to recognize lifelong contributions to the field of nonlinear dynamics.These awards recognize lifelong impact of research contributions, education and training of researchers and/or practitioners, and overall leadership in advancing the field. Nominations should include (1) a nomination letter describing the field of, and the impact of, the nominee, (2) a curriculum vitae, and (3) up to five letters of support. All nomination materials must be submitted in electronic (pdf) format.Submit nomination materials beforeJuly 1, 2006to either one of the Co-Chairs of the Awards Subcommittee.Professor Olivier A. BauchauCo-Chair MSND-TC AwardsSchool of Aerospace EngineeringGeorgia Institute of Technology270 Ferst Street, SST Building, Rm. 212Atlanta, GA 30332-0150Email: olivier.bauchau@ae.gatech.eduTel: (404) 894-0042Fax: (404) 894-2760Professor Noel C. PerkinsCo-Chair MSND-TC Awards SubcommitteeMechanical EngineeringUniversity of Michigan2350 Hayward St.Ann Arbor, MI 48109-2125Email: ncp@umich.eduTel: (734) 936-0403Fax: (734) 615-6647

We present a parallelized geometric multigrid (GMG) method, based on the cell-based Vanka smoother, for higher order space-time finite element methods (STFEM) to the incompressible Navier–Stokes equations. The STFEM is implemented as a time marching scheme. The GMG solver is applied as a preconditioner for generalized minimal residual iterations. Its performance properties are demonstrated for 2D and 3D benchmarks of flow around a cylinder. The key ingredients of the GMG approach are the construction of the local Vanka smoother over all degrees of freedom in time of the respective subinterval and its efficient application. For this, data structures that store pre-computed cell inverses of the Jacobian for all hierarchical levels and require only a reasonable amount of memory overhead are generated. The GMG method is built for the deal.II finite element library. The concepts are flexible and can be transferred to similar software platforms.

The methods of multibody system dynamics provide most of the numerical tools required to construct models of vehicles and to describe biomechanical models of occupants with accuracy. Some of the most recent developments in this area of applied mechanics extended the basic capabilities of the multibody formulations to include the description of the system components deformation. For a given model of a vehicle each moving part is represented as a rigid body or as a flexible body experiencing linear elastic or fully nonlinear deformations. The relative motion of the system components is described by imposing kinematic constraints between them. the interactions among the system components, with other objects and multibody systems or even the coupling with the equations of other disciplines to describe aerodynamics effects or contact-impact conditions are efficiently modeled in this numerical environment. These characteristics suggest that the multibody methodologies provide appropriate ingredients to develop not only the simple conceptual models used in the early phases of the design process but also the more elaborate models of complex systems required for analysis. In this work, the position and orientation of each body of the system is described by a set of Cartesian coordinates or by natural coordinates, which consist in a set of points and vectors representing each body. For flexible bodies. the linear or nonlinear deformations are described with reference to a body fixed coordinate system using an updated Lagrangean formulation and the finite element method. In this form the equations of motion of the flexible bodies exhibit the coupling between the gross rigid body motion and the component flexibility. The relative motion between each of the multibody, components is assured by imposing kinematic constraints in the form of algebraic equations that relate the coordinates used to describe the system. The contact and impact between the system components and other bodies, internal or external to the system. is described using a continuous contact force model. Alternatively, unilateral constraints representing motion restrictions for a particular body in contact, are used. For situations where the deformed region of the component in contact is much smaller than the region of the same body that behaves in a rigid manner a kinetostatic formulation is used. Here, the inertial coupling between the body deformations and its gross motion is neglected. Finally, the formulations reviewed are applied to the description of a biomechanical model and several vehicle models that are simulated in different scenarios, including vehicle rollovers with and without occupants and pedestrian impact. Based on these applications the advantages of using a unified formulation to describe all systems are discussed.