Friction behavior is one of the most critical factors in brake system design and performance. For up-front design and system modeling it is desirable to be able to describe a lining's frictional behavior as a function of the local conditions, such as contact pressure, temperature and sliding speed. Typically, frictional performance is assessed using brake dynamometer testing of full-scale hardware, and an average friction value is used during brake system development. This traditional approach yields an average brake friction coefficient that is hardware-dependent and fails to capture in-stop friction variation; it is also unavailable in advance of component testing, ruling out true up-front design and prediction.
To address these shortcomings, a scaled inertial brake dynamometer was used to determine the frictional characteristics of candidate lining materials. Dynamic modeling techniques were then applied to develop a hardware-independent, empirical friction function with respect to contact load, rotor temperature and rotor speed. It was demonstrated that a growth model can be used for dynamic prediction of the instantaneous friction coefficient and rotor temperature during simulated braking events. Nonlinear regression and numerical optimization techniques were applied to solve the dynamic equations that describe local friction and temperature as a function of initial load.