From tribometer to dynamometer: Predicting brake friction and wear during a WLTP-B cycle using a cellular automaton approach

The Euro 7 regulations have increased the need for predictive methodologies capable of evaluating brake friction, wear, and particle generation under representative operating conditions. While full-scale dynamometer testing remains the standard approach for brake system evaluation, it is resource-intensive and limits efficient material development. A multiscale modelling framework linking pin-on-disc (PoD) tribometer experiments, mesoscale cellular automaton (CA) modelling, and full-scale brake system simulation is proposed and evaluated for a single material combination consisting of a low-metallic brake pad and a laser-cladded TiC-coated disc. Friction and wear properties obtained from PoD measurements are used directly as input to a CA model describing the evolution of the pad-disc contact interface. The model is applied to a complete WLTP-B braking cycle and validated against full-scale dynamometer measurements without calibration. Predicted mean coefficient of friction was 0.574 compared with a measured value of 0.545, corresponding to a deviation of 5.3%, while the predicted wear emission factor was 14.6 mg/km compared with 14.1 mg/km experimentally, corresponding to a deviation of 3.5%. The model reproduces the transient evolution of friction during individual braking events and provides spatially resolved predictions of contact area, pressure distribution and friction. The results demonstrate that PoD-derived tribological parameters, when combined with a physically based CA framework, enable quantitative prediction of full-scale brake performance under WLTP-B conditions without calibration against dynamometer data. The proposed methodology suggests a computationally efficient tool for virtual material screening and offers mechanistic insight into the tribological processes governing friction and wear in automotive braking systems.