Ahmed, I., "Analysis of Ventilated Disc Brake Squeal Using a 10 DOF Model," SAE Technical Paper 2012-01-1827, 2012, doi:10.4271/2012-01-1827.
Squeal of disc brakes is considered as a main source of discomfort for passengers. Typically 1 to 4 kHz noise is considered low frequency squeal and ≻8 kHz noise is considered high frequency squeal. It is a significant problem in passenger vehicles for the comfort of the passengers and a significant financial problem for industry too. Many manufacturers of brake pad materials spend up to fifty percent of their engineering budgets on noise, vibration and harshness (NVH) issues. Squeal noise is strongly correlated to the squeal index and degree of instability of the brake system assembly. Decreasing this squeal noise to some extent during braking is very important matter for the comfort of passengers. So, a mathematical prediction model of 10-degree-of-freedom has been developed to study the effect of different brake components parameters on the degree of instability and squeal index of the brake system. The model has considered such factors as the distance between clamping bolts of the caliper which was not fully covered previously besides some other factors as width and thickness of the friction material. Complex eigenvalue analysis by MATLAB has been used to predict the unstable frequencies of the ventilated disc brake system assembly. It is evident from the analysis that squeal noise of the brake decreases with increasing semi-distance between the clamping bolts of the caliper and with the increase in friction material thickness. However, the squeal noise decreases with increasing the width of the friction material and Young's modulus of both rotor and friction material. The results also show that the width of the friction material has a major effect on the occurrence of the squeal noise of the brake assembly and as it increases, the squeal index decreases.