Comparison of the theoretical and experimental coefficient of friction for the brake disc-brake pad system

Abstract

Contact between the automotive brake pad and the disc is mathematically modelled to estimate the coefficient of friction (COF). The mathematical model is proposed for the prognosis of the COF of brake pad material, by considering the contact mechanics between the interfacing surface and their material properties. The Greenwood-Williamson contact model is applied for rough contact surfaces for the estimation of the real contact radius. A MATLAB program has been formulated for generating the surface of brake pad material by considering its material properties which aid in the analytical evaluation of the COF. The proposed model is further validated with experimentation on pin-on-disc apparatus, as it is considered suitable for friction pad product testing according to previous research. The 25 pins were fabricated as per the ASTM G99 test for testing under varying loads and speeds. The obtained results showed that the range of COF has been between 0.2 and 0.4. The investigation presents an analytical approach for estimating COF and contact radius for brake disc and brake pad, which can be used to design an efficient automotive brake disc-brake pad system under the given load and rotational speed. The artificial neural network (ANN) is modelled for predicting the values of the COF for brake disc-brake pad systems, which can be further used for determining the tribological properties of new friction materials and their compatibility for efficient brake systems.