Abstract: Based on the closed-loop coupling modal of disc brake structures， an optimal method and static loaded modal test were used to extract the actual contact coupling stiffness with different brake pressures applied， and the connection between the brake pressures in the actual conditions and the contact coupling stiffness in the parametric model was established. Subsequently， the sensitivity analysis method was used to explore the effect of the contact coupling stiffness on the unstable tendency of the brake system. Finally， according to the corresponding relationship of brake pressures and contact coupling stiffness， the effect of contact coupling stiffness on the unstable tendency was transformed into the impact of the brake pressure on the high frequency braking squeal. The sensitive range of the brake pressure making the system tend to be unstable could be obtained， which is helpful to put forward the active control measures to suppress the high frequency braking squeal.

Key words: closed-loop coupling model, optimal method, static loaded modal test, contact coupling stiffness, brake pressure, high frequency braking squeal