A general approach for efficient embedding of flexible structures in multibody dynamics

In this short paper, we present a general method to embed flexible structures into rigid multibody systems. The flexible structure is seen as a force element contained in the multibody system formalism. This allows to use well established integrators for the multibody dynamics simulation, while suitable integrators are used for the co-simulation of the flexible part. To find the coupling forces an algebraic constraint is used and the necessary Lagrange multiplier is computed efficiently by solving a reduced monolithic index-1-system. This keeps the method very general for different flexible structures, interfaces and coupling joints. In order to be applicable in interactive multibody dynamics simulation, efficient models of flexible structures with cheap evaluations should be used. High dimensional 3D finite elements are computationally too expensive, therefore the special geometry of flexible structures should be exploited. E.g., a geometrically exact Cosserat rod, a cable model that was developed at the Fraunhofer Institute for Industrial Mathematics, is well-suited and used in this work for numerical experiments.