Brake pad and disc wear is a significant factor in determining the maintenance intervals for motor vehicles. The ability to improve pad and disc life and thereby increase maintenance intervals requires fundamental studies of new and advanced friction pairs. Wear is essentially influenced by two factors, the friction power acting at the contact surfaces, which is in turn a function of brake pressure, friction coefficient and driving speed, and the temperature at the friction surface.
A model has been developed describing the wear process and consising of four interlinked modules:
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a module describing the driving dynamics;
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a structural mechanical module describing the contact situation between pad and disc;
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a thermomechanical module representing the thermal conduction in pad and disc, and
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a law of wear.
Based on wear values experimentally determined on a dynamometer, the model predicts the wear of a friction pair during a vehicle endurance run. The report describes two numerical models for the qualitative examination of the brake system parameters responsible for wear. The first model is a 3-dimensional FE model representing the physical phenomena occurring at the contact surface between pad and disc during the braking process. In the second calculation model, pad and disc are reduced to a point mass model in order to minimise the calculation effort.
In the first part of the report, a law of wear is formulated on the basis of extensive dynamometer trials and used to determine the main parameters influencing wear. This law of wear is verified by road test results. In the second part, the influence of different driving conditions and laws of wear on the wear of friction pairs is simulated by the two models, followed by a comparison of results.