REDUCTIONMETHODS FOR LARGE-SCALEMULTIBODY SYSTEMS

Abstract. The floating frame of reference formulation (FFRF) has become a standard for the modeling of deformable moving bodies. In the FFRF, the component mode synthesis method is utilized in order to reduce the number of unknowns in a complex model. Some of the drawbacks of this methodology are the large number of static modes in the case of complex coupling of bodies, e.g. in contact problems or in advanced joint models, and the large number of dynamic modes for the case of high frequency analysis, e.g. for the analysis of the acoustic behavior of a car body. Standard nonlinear finite element methods are known to be computationally very expensive compared to modally reduced methods. An efficient formulation based on absolute coordinates with a reduced co-rotated strain tensor has been derived recently and the analogy to the floating frame of reference formulation has been shown. The efficiency of this formula-tion is based on a co-rotated constant mass and stiffness matrix that is factorized only once for the whole simulation. It turned out that this formulation has advantages in the case of prob-lems with nonlinear materials or contact of flexible bodies. Furthermore, a modal reduction is possible for this formulation in the planar and linear elastic case, which can reduce the com-putational costs again. As a common problem in the multibody formulations, the number o