Component mode selection in flexible multibody dynamics with application to cranktrain modelling.

This paper discusses the development of a multibody model of a Ducati L-twin engine cranktrain, with an emphasis on component flexibility and model reduction. In fact, the main components in the system are modelled as flexible: starting from a Finite Element description of such components, the standard Craig-Bampton technique is employed to reduce the model order. The Effective Interface Mass measure of dynamic importance is used to rank fixed-interface normal modes based upon their contribution to loads at the substructure interface; modes to retain are then selected according to such modal ordering scheme. In order to assess the performance of the adopted modal selection criterion, tests are performed on both the connecting rod model, by means of dynamic linear simulations in time and frequency domain, and the complete cranktrain assembly, through nonlinear multibody analyses. Results concerning both accuracy and efficiency are presented and discussed.