Nonlinear effects on the self-excited oscillations known as motorcycle chatter

Nonlinear effects on the stability of the motorcycle rear ‘chatter’ phenomenon are investigated by means of a minimal two degrees of freedom model. Motorcycle ‘chatter’ consists of a self-excited oscillation which occurs during braking manoeuvres in the frequency range between 17 and 20 Hz. It causes loss of rider confidence and leads to decreased performance. The study of the linearised system gives indications on the initiation of self-excited vibrations and thus helps to prevent them using proper design techniques, while nonlinear analysis can lead to completely new insights. Post-bifurcation behaviour is analysed focusing on limit cycles, studied by means of an application of the harmonic balance method. This allows the detection of the validity of the linear results, and to identify the most influential parameters in limit cycle generation, their amplitude, and their stability.