An advanced multibody code for handling and stability analysis of motorcycles

This work illustrates the modelling aspects of an advanced motorcycle multibody model which captures the most important features of the vehicle, including five different suspensions schemes (telescopic fork, telelever, duolever swingarm and paralever) all provided with their own flexibilities. Several lumped stiffness are used to model the structural compliance of the frame as well as the flexibility of the transmission system. A passive rider model which simulates the interaction of the rider with the handlebar and the chassis and a 3D road-tire model which takes into account both the carcass geometry and compliance are also included. The presented mathematical model performs nonlinear time domain simulations, non-linear steady state analysis, linear stability and frequency domain analyses. Some simulation examples are presented: a steady state cornering manoeuvre where the decomposition of steering torque in its main components is carried out, a stability analysis where the effects of rider's impedance and structural flexibilities on weave and wobble vibration modes is highlighted, a stability analysis of a braking motorcycle which experiences a chatter instability and a lane change manoeuvre where the main handling indexes are computed.