Methodology for Sizing and Validating Life of Brake Pads Analytically

An area of brake system design that has remained continually resistant to objective, computer model based predictive design and has instead continued to rely on empirical methods and prior history, is that of sizing the brake pads to insure satisfactory service life of the friction material. Despite advances in CAE tools and methods, the ever-intensifying pressures of shortened vehicle development cycles, and the loss of prototype vehicle properties, there is still considerable effort devoted to vehicle-level testing on public roads using “customer-based” driving cycles to validate brake pad service life. Furthermore, there does not appear to be a firm, objective means of designing the required pad volume into the calipers early on - there is still much reliance on prior experience. This paper builds upon previous work by GM [1], where short duration, objective vehicle and dyno tests were combined with a computer model to allow for accurate pad service life prediction without vehicle tests, and expands it into a methodology combining CAE (CFD), computer modeling, objective friction material characterization data, to enable confident sizing of the brake pads very early in the vehicle development process. In the present work, this method is extended to global vehicles, considering a European-market vehicle (low-metallic lining materials). A case study vehicle will be used to illustrate how these tools and methods can be used to design the initial pad volume, develop the brake system to avoid lining life issues, and then validate the brake pad service life for global vehicles, without using expensive, time consuming, and often inaccurate public road testing.