Finite element analysis of wear and temperature development in heavy-duty disc brakes

Abstract

As exhaust emissions from vehicles continue to decline, non-exhaust emissions, particularly those arising from brake and tire wear, have become a critical area of interest and regulatory focus. The EU Euro 7 regulation will, for the first time, set requirements on the particle emission behaviour of brake systems and tires. Hence, the aim of this MSc thesis is to investigate wear and temperature development in truck disc brakes through the development of finite element (FE) models, which is validated against rig-test data. In addition, material parameters are calibrated towards measured data. The FE-modelling consisted of axisymmetric and three-dimensional representations of both the entire brake assembly and a simplified half-model. Thermal and thermomechanical simulations of disc crack tests were performed on the models using the commercial software Abaqus to study the wear and temperature development. The thermal models were used with the optimisation software modeFRONTIER to fit and calibrate thermal material parameters. The results of the different models were compared with each other and with rig-test data. The results showed that thermal axisymmetric models are efficient for fast temperature prediction and parameter fitting, but are limited in their ability to capture local contact effects, hot-spotting and non-uniform wear. The thermomechanical models provided a more detailed description of the interaction between contact pressure, temperature and wear, and showed that local temperature peaks and wear patterns can strongly influence the brake response. The 3D-model further demonstrated the importance of circumferential variations in the pad and disc, although its computational cost limited the possible mesh refinement and the duration that could be simulated. For multiple stop simulations, the use of a temperature dependent wear scaling factor gave a temperature development closer to the rig-test data, while the constant wear scaling factor gave wear results closer to the measured values. The parameter calibration showed that modeFRONTIER can be used to fit thermal and wear-related parameters, but also highlighted the risk of compensating for model simplifications with parameter tuning.