Mathematical modelling of friction induced high frequency noise and vibration mechanism in vehicle brake systems through experimental data

Friction induced brake squeal problem is not solved comprehensively despite several proposed theories about its mechanisms, and being frequently studied. Therefore, this study aims to make contribution to the relevant literature by obtained experimental data and built mathematical model. Firstly, experimental modal analysis of the brake disc, caliper, bracket and pads, are performed. Afterwards, disc and pads, which have critical roles in squeal mechanism, are numerically modelled by using finite element methods. Then, model updating is performed to reach good correlation between the experimental and computational resonant frequencies. Afterwards, high amount of brake squeal experiments are conducted by altering disc velocity, brake pressure and temperature on a laboratory set-up by acquiring sound pressure and acceleration data. Additionally, operational deflection shape analysis is executed on the system, during selected operation conditions. Lastly, a mathematical model, which focuses on the interactions between the disc and pad, is developed to explain squeal induction mechanisms that observed in the experiments. Experiments and mathematical model shows good agreement. It is concluded that the squeal dynamics and frequencies are depended on changing contact stiffness between the disc and pad due to changing brake pressure, and closely related to natural frequencies of the disc and caliper fingers.