Multibody Analysis of the Desmodromic Valve Train of the Ducati MotoGP Engine.

This paper presents a preliminary study concerning a multibody model of the desmodromic valve train used in the Ducati MotoGP engines. The desmodromic mechanism has a positive cam that causes the dynamic effects to be partly different from common valve trains, where the valve spring plays an important role. The presented model includes only one camvalve mechanism. In a further step of the research, it will be possible to develop and expand the model by introducing the other cam-valve mechanisms and other mechanical parts that compose the system in order to obtain a complete model of the valve train. In the first part of this work, the generation of the cam profiles is explained. The second part is focused on the description of the multibody model employed for the dynamic simulations. Finally, the experimental validation is presented and discussed. The comparison between the numerical results and the experimental data is encouraging even if it shows that the effectiveness of the model is not completely achieved. Therefore, it will be necessary to improve the model by including the presence of other mechanical parts of the valvetrain, as well as other important dynamic effects as, for example, the link flexibility.