A reduction strategy at system level for flexible link multibody systems

This paper introduces a technique for the reduction of nonlinear models of flexible-link multibody systems formulated through the Equivalent Rigid-Link System approach. Model order reduction is performed at the full system level (often denoted "a posteriori") to ensure that the full-order model is properly approximated in the selected frequency range and in the whole workspace. To achieve such an objective, the well-known Craig-Bampton reduction technique and the Interior Mode Ranking method are suitably modified and combined to formulate a configuration-dependent reduction transformation that handles model nonlinearities. In such a way, the dependence of the full-order model on the system configuration, as well as other nonlinearities, can be represented by the reduced model. The proposed method has been assessed through a flexible-link planar manipulator with five flexible links and whose equivalent rigid-link system has three degrees of freedom.