A consistent and efficient framework for the time integration of multibody systems with impacts and friction

Speaker: Thorsten Schindler   ABB Corporate Research Center, Germany

Date: Wednesday, February 22, 2017

Place: USI Lugano Campus, room A-23, Red building (Via G. Buffi 13)

Time: 10:30

Abstract: 

In this work, we discuss time integration schemes for the dynamic simulation of nonsmooth flexible multibody systems. We develop a framework for the consistent treatment of velocity jumps, e.g. due to impacts. A non-impulsive trajectory of state-variables is improved by an impulsive correction after each time-step if necessary. This correction is automatically chosen starting from a non-impulsive base integration scheme, which discretizes the propagation within the time-step. Consistency is achieved due to the impulsive corrections on the same kinematic level as the treatment of non-impulsive constraints. This idea stems from a time-discontinuous Galerkin setting, but is generalized concerning the splitting of non-impulsive and impulsive force propagation. In this work, we compare the behaviour of four different base integration schemes in the newly developed framework as well as a classical Moreau-Jean timestepping scheme concerning selected criteria and examples from academics and industry. It turns out that the half-explicit timestepping is a very robust and the most efficient method as far as we deal with non-stiff problems. The timestepping schemes based on the generalized-alpha method, the Bathe method and the ED-alpha method become most efficient for stiff problems with spurious oscillations. In our test cases the generalized-alpha method is the most efficient base integration scheme concerning computing time, however it may get unstable in the nonlinear regime. The ED-alpha method satisfies exactly the opposed characteristics. It is the Bathe-method, which seems to be the best compromise concerning stability and efficiency in the nonlinear regime. We propose it as a base integration scheme for timestepping methods whenever stiff problems with impacts and friction have to be solved.  

Biography:

  ·         Since 2015: Senior Scientist, ABB Corporate Research Center Germany

o    Development of next generation breaker prototypes in an interdisciplinary group of mechanical and electrical engineers.

o    Statistical optimization of robust designs in simulation and testing.

o    Sophisticated mechanical modeling including clearance, impact and friction models.

o    Coupling and co-simulation of mechanical, electro-magnetical and hydrodynamical phenomena.

·         2011-2015: Research group leader 'numerical simulation' and habilitation candidate, Institute of Applied Mechanics, TU MünchenThesis: Consistent Time-Integration Schemes for Flexible Multibody Systems with Friction and Impacts. Examiner: Prof. Dr. Daniel Rixen, Prof. Dr. Wolfgang Wall, Prof. Dr. Christoph Glocker

·         2010-2011: PostDoc, BiPoP team, INRIA Grenoble Rhône-AlpesPublication: Timestepping schemes for nonsmooth dynamics based on discontinuous Galerkin methods: definition and outlook. Collaborator: Dr. Vincent Acary

·         2006-2010: Scientific research assistant and PhD student, Institute of Applied Mechanics, TU MünchenThesis: Spatial Dynamics of Pushbelt CVTs, Examiner: Prof. Dr. Heinz Ulbrich, Prof. Dr. Martin Arnold 

·         2001-2006: Diploma (M.S.) Technomathematik, TU MünchenThesis: Domain decomposition methods for parabolic partial differential equations. Advisor: Prof. Dr. Bernd Simeon  

Host: Prof. Rolf Krause