Simulation of contact dynamics in automotive brakes with an Abstract Cellular Automaton

A new multiphysics simulation program, the Abstract Cellular Automaton, is introduced in this work towards simulating the entire macroscopic tribological contact between a brake pad and disc. Detailed analyses of highly influential micro- and mesoscopic contact areas are carried out, and the surrounding contact areas are analyzed with lower resolution. This is achieved through a novel combination of specialized cellular automata. Simulations are carried out on multiple timescales. On the long timescale, the Abstract Cellular Automaton is validated through tribological measurements. Known braking phenomena are then reproduced, and new perspectives on established dynamic interdependencies are revealed. On the short timescale, the vibrational motion of the contact structures is related to fluctuations of crucial global tribological dynamics. Theoretical braking scenarios are implemented to depict fundamental phenomena and dependencies. A realistic multi-timescale study is then carried out, in which the natural development of the contact topography is simulated and directly used in a vibration analysis. The influence of load history is thus investigated. Synchronized vibrations in the friction contact can excite vibrations of the bulk friction materials, resulting in disruptive noise and vibrations. To identify and characterize the relevant synchronization behaviors, the Frequency-Decomposed Meta Group analysis and the Synchronization Index are developed. Together, they provide an aid towards understanding the triggering mechanisms of brake squeal.