Model reduction in co-rotated multi-body dynamics based on the dual craig-bampton method

A new reduction method for dynamical analsis of multi-body systems is presented in this paper. It fundamentally differs from the ones previously published in the way kine-matical constraints are handled. Our approach is based on component mode synthesis, but the specificity of articulated mechanism, in which components are assembled through connecting forces, is taken into account from the reduction level. This is achieved by using a set of modes that are consistent with this type of assembly, namely the residual flexibility modes and the free-free vibration modes. In this approach, Lagrange multipliers naturally appear as generalized reduced coordinates together with the vibration modes' amplitudes. An other specific difficulty pertaining to articulated systems is the configuration dependency of the residual flexibility modes. In order to overcome this obstacle a new strategy to handle kinematical constraints has been developed, enabling us to ignore the current direction of the constraint forces at the reduction level by splitting the constraint into local and global contributions. The derived reduced matrices are remarkably simple and the procedure is easy to implement. The validity of the approach will be investigated using the crank-slider benchmark.