A Simple Model for the Simulation of Low-Frequency Disc Brake Noise

A simple ADAMS model was developed for simulating one possible mechanism that causes low-frequency (less than 1 kHz) noise in disc brake assemblies for heavy-duty and medium-duty trucks. The model consists of: truck tire, axle housing, torque plate, caliper, push rods, inner pad, outer pad, and rotor. Only one component (the torque plate) was modeled as a flexible body (using a finite element model), while all other parts are considered as infinitely rigid. A lumped parameter representing the suspension wrap-up stiffness resists the axle pitch motion. When the brakes are not engaged, the system has two distinct modes of vibration, namely, the axle pitch mode which is governed by the suspension wrap-up stiffness, and the caliper transverse (side-to-side) mode, which is governed by the stiffness of the torque plate (out-of-plane deflection of the torque plate) and by the suspension lateral stiffness. When the brakes are engaged, there is a possibility that the two vibration modes may coalesce into one system mode of vibration, the frequency of which is distinct from any of the two underlying modes of vibration. The probability of the occurrence of this mode coalescence primarily depends on the compressibility (compliance along the direction of the normal contact force) of the friction pads.