Experimental and numerical investigations of thermo-mechanical instability of the industrial disc brakes

This paper presents the brake disc surface temperature field measurements, during emergency braking in real industrial conditions, by means of the thermovision infra-red camera. The temperature field assessment enables the verification of the numerical modelling of the brake performance in the succeeding step. The experimental part of the research also covers tribological testing on the coefficient of friction between friction brake material (brake pad) and steel (brake disc) in laboratory conditions on the tribotester which satisfied the similarity criteria with the mine winder hydraulic disc brake. The tribological characteristic of the friction couple, including kinetic and static coefficients of friction, was determined for use in the finite element analysis of the brake thermo-mechanical instability problem. In the numerical part, the finite element modelling technique was used to simulate the brake interface hot spotting and the axial disc distortion as a function of geometrical and material properties of the brake elements, and the brake’s operational conditions. The critical speed above which thermo-mechanical instability would occur was calculated for the analysed mine winder brake system. A finite element method was used to find not only temperature distribution but also the resulting thermal stresses and distortions in the brake discs. The disc division into various numbers of sections was numerically tested for the division’s effect on the thermal stress reduction and the axial distortions.