Multibody simulation (MBS) is a method of numerical simulation in which multibody systems are composed of various rigid or elastic bodies. Connections between the bodies can be modeled with kinematic constraints (such as joints) or force elements (such as spring dampers). Unilateral constraints and Coulomb-friction can also be used to model frictional contacts between bodies.[1] Multibody simulation is a useful tool for conducting motion analysis. It is often used during product development to evaluate characteristics of comfort, safety, and performance.[2] For example, multibody simulation has been widely used since the 1990s as a component of automotive suspension design.[3] It can also be used to study issues of biomechanics, with applications including sports medicine, osteopathy, and human-machine interaction.[4][5][6]

The heart of any multibody simulation software program is the solver. The solver is a set of computation algorithms that solve equations of motion. Types of components that can be studied through multibody simulation range from electronic control systems to noise, vibration and harshness.[7] Complex models such as engines are composed of individually designed components, e.g. pistons/crankshafts.[8]

The MBS process often can be divided in 5 main activities. The first activity of the MBS process chain is the” 3D CAD master model”, in which product developers, designers and engineers are using the CAD system to generate a CAD model and its assembly structure related to given specifications. This 3D CAD master model is converted during the activity “Data transfer” to the MBS input data formats i.e. STEP. The “MBS Modeling” is the most complex activity in the process chain. Following rules and experiences, the 3D model in MBS format, multiple boundaries, kinematics, forces, moments or degrees of freedom are used as input to generate the MBS model. Engineers have to use MBS software and their knowledge and skills in the field of engineering mechanics and machine dynamics to build the MBS model including joints and links. The generated MBS model is used during the next activity “Simulation”. Simulations, which are specified by time increments and boundaries like starting conditions are run by MBS Software. It is also possible to perform MBS simulations using free and open source packages. The last activity is the “Analysis and evaluation”. Engineers use case-dependent directives to analyze and evaluate moving paths, speeds, accelerations, forces or moments. The results are used to enable releases or to improve the MBS model, in case the results are insufficient. One of the most important benefits of the MBS process chain is the usability of the results to optimize the 3D CAD master model components. Due to the fact that the process chain enables the optimization of component design, the resulting loops can be used to achieve a high level of design and MBS model optimization in an iterative process.[9]

References

  1. ↑ Schindler, Thorsten. "Multi-Body Simulation". Courses: Technische Universität München. Technische Universität München. Retrieved 20 August 2013.
  2. ↑ Larsson, Tobias. "Multibody Dynamic Simulation in Product Development" (PDF). Division of Computer Aided Design Department of Mechanical Engineering Luleå University of Technology. Luleå University of Technology. Retrieved 29 August 2013.
  3. ↑ Blundell, Mike and Damian Harty (2004). The Multibody Systems Approach to Vehicle Dynamics. Oxford, MA: Elsevier Butterworth-Heinemann. ISBN 0750651121.
  4. ↑ Al Nazar, R.; T. Rantalainen; A. Heinonen; H. Sievänend; A. Mikkola (2008). "Flexible multibody simulation approach in the analysis of tibial strain during walking" (PDF). Journal of Biomechanics. 41 (5): 1036–1043. doi:10.1016/j.jbiomech.2007.12.002. hdl:10536/DRO/DU:30036187. PMID 18191865.
  5. ↑ O’Riordain, K.; P.M. Thomas; J.P. Phillips; M.D. Gilchrist (August 2003). "Reconstruction of real world head injury accidents resulting from falls using multibody dynamics". Clinical Biomechanics. 18 (7): 590–600. doi:10.1016/S0268-0033(03)00111-6. hdl:10197/5951. PMID 12880706. S2CID 41827906.
  6. ↑ "Industrial Sectors: Biomechanics". SIMPACK. SIMPACK AG. Retrieved 27 August 2013.
  7. ↑ "Definition of MultiBody Dynamics Simulation". Function Bay: RecurDyn. Retrieved 20 August 2013.
  8. ↑ "SimMechanics Introduction". MathWorks. Retrieved 20 August 2013.
  9. ↑ Faath, A. and Anderl, R. Interdisciplinary and Consistent Use of a 3D CAD Model for CAx Education in Engineering Studies. In ASME 2016 International Mechanical Engineering Congress and Exposition (pp. V005T06A031-V005T06A031). American Society of Mechanical Engineers. November 2016
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