T-3-1-3 Flexible Multibody Dynamic Analysis using Reduced Deformation Modes

This paper presents an efficient method for flexible multibody dynamic analysis. The proposed method is the one using reduced deformation modes, which are obtained from the finite element model with reduced nodal degrees of freedom. In case of a large-scaled flexible body in multibody systems, i. e. a vehicle body structure, the finite element model of the body has such many nodal degrees of freedom that computational costs should be increased. They result in decreasing efficiency of flexible multibody dynamic analyses. Using reduction methods such as the Guyan one, the generalized dynamic one and the component mode synthesis one, etc, Total nodal degrees of freedom of a finite element model are divided into master and slave ones. And then the reduced model corresponding to the master nodal degrees of freedom is gained and reduced deformation modes are computed from the reduced model. Flexibility information corresponding to the reduced deformation modes is economically obtained in terms of nodal coordinates, mode shapes, modal stiffness matrix, modal mass matrix and lumped mass matrix. Using the virtual work principle, the equation of motion of the flexible body is derived with a few assumptions according to reduction of nodal degrees of freedom. The effectiveness of the proposed method is verified in numerical examples of a high-speed rotating beam and a bump-passing mini-bus.