Friction and wear performance of disc brake pads and pyroelectric energy harvesting

摘要

Due to the perpetual development of new technologies in the transportation industry, vehicles become more powerful and faster. As a result, the braking systems have to simultaneous follow this same rate of progression. The brake, a major safety organ, gets significant interest of engineers and researchers. The main purpose of this paper is to present a study based on numerical modelling coupling the thermodynamic and the thermoelectrical behaviours of an automobile brake disc for the prediction of the wear of disc brake pads and the time to be changed, as well as the harvesting of the thermal energy resulting from the braking operation. Firstly, an analysis of the thermal phenomena operating in a brake disc in service (heat flow generated by friction, high thermal gradients, temperature rise, and the speed of rotation of the disc) is presented. The proposed modelling is carried out taking into account the influence of different parameters such as the type of braking, the cooling mode, and the design materials. Then, the studies are focused on the use of a smart material for heat recovery due to the contact between the disc and the pads, this material has a capability of converting thermal energy into exploitable electric energy, as a consequence, we can predict the state of health and proper time to change the pads. This study is based on the pyroelectric effect, for a good prediction of the proper time to change the pads. The magnitudes of the voltage generated and the energy density harvested are shown as a function of the pads thicknesses, the speed and the temperature traversed by the pyroelectric material PZT.