Analytical study of brake groan through a coupled 2DOF brake model

Brake groan is a friction-induced vibration occurring on the contact surface between rotor and brake in a vehicle. In this paper, a two degree-of-freedom rotor and brake model driven by a displacement input is adopted to investigate this unique stick–slip motion. The detailed modeling method is developed and analytical solution for a whole stick–slip cycle is also provided. Analytical solution is obtained by Laplace transform theory for this piecewise linear model. Through variation of driving displacement, a perturbation study is carried to identify the effect of this input on the stick–slip motion. The obtained results for each case are grouped into different motion types based upon different stick and slip phase period as well as their unique phase plots for individual case. The analytical solution and numerical results both indicate that brake groan frequency is directly affected by the driving input.