Reduction of Finite Element model for the Multibody Simulation with respect to the contact problem in jointed structures

The global mechanical characteristics of complex elastic structures, which are assembled of substructures, are significantly influenced by the local and nonlinear tribological effects inside the involved joints, like bolted joints, spot welded seems and others. In classical mechanics, tribological effects and global vibrations are treated differently at least on the level of discretisation. In the present contribution, an extension of common mode bases is suggested in order to account for the local non-linear characteristics of the joints. For that sake, special modes, which we call joint interface modes, are added to an existing mode base in order to compute the state due to non-linear joint forces with a sufficient accuracy. Excellent displacement results are obtained by the classical CMS modes and a manageable number of additional ‘joint interface modes’.