Effective Simulation of the Boundary Layer of an Entire Brake Pad
Published September 27, 2015 by SAE International in United States
Annotation of this paper is available
The dynamic friction behavior of automotive brakes is generated by the boundary layer dynamics between pad and disk [OST01]. A key component of the Friction Interface is the influence of mesoscopic surface contact structures known as patches, upon which the friction power is concentrated, and whose sizes vary with time. Through this dynamic process, time and load history-dependent effects come about, which cause, for example, the brake moment behavior commonly observed in an AK-Master test.
In recent years, several simulation tools have been developed in order to predict the complex friction behavior caused by the patch dynamics in the friction boundary layer. Such simulations are often based on a two or three-dimensional spatial grid, where the explicit physical phenomena at all locations in the boundary layer are modeled by time-consuming calculations of local material dependent balance equations.
A new abstract Cellular Automata simulation tool is introduced, which reduces the necessary computation to the patches in the friction boundary layer. Rather than making use of a spatial grid, each patch is considered a single cell, whose size can be adjusted without added computation costs. Using this method, the friction and wear behavior of an entire brake pad can be computed more quickly than, and at least as accurately as previous simulation tools could simulate a small subsection of the pad.