Elastodynamic analysis of the desmodromic valve train of a racing motorbike engine by means of a combined lumped/finite element model

A combined lumped/finite element model of a portion of the desmodromic valve train of a racing motorbike engine was developed and validated in order to simulate the elastodynamic behaviour of such a particular timing system. The model includes the lumped parameter model of the belt transmission that drives the camshafts, the finite element model of the camshafts, and the lumped parameter model of two cam-valve mechanisms (one for each camshaft). The procedure to validate the model, based on experimental tests carried out on a test bench described here, is presented and discussed. The comparison between the numerical results and the experimental data shows that the effectiveness of the model is satisfactorily achieved. It will be possible, in a further study, to add the other cam-valve mechanisms and the missing external forces, in order to obtain a complete system model. Some possible applications of the presented model are provided in order to show how the overall model could be employed to perform both design optimisation and diagnostics.