A Finite Element Approach to Drum Brake Analysis

Abstract

Conventional methods of brake analysis ignore the distortions of shoe and drum and are acknowledged to give inaccurate predictions of brake torque. Whilst they are adequate for very general design purposes the problem of advanced design demands a more rigorous treatment. The modern technique of finite elements, adapted to deal with the case of a friction interface, where contact is not necessarily maintained over the whole lining area, appears to be a logical approach to the problem. A simple model of shoe and lining is presented as a means of obtaining both improved accuracy and a development capability for including drum distortions and thermal effects. This model is supported by the theory of a beam on an elastic foundation in order to illustrate the importance of the relative stiffnesses of shoe and lining. Validation of the finite element model is undertaken by carrying out performance tests on a brake mounted on an inertia dynamometer and the results are used to show that the divergent types of pressure distribution predicted by earlier theories and by recent research are all compatible with practical experience and that they can account for some of the differences in performance which are found in service under various conditions. * Program for Automatic Finite Element Calculations—a commercially available software package developed by the Mechanical Engineering Department of Nottingham University and associates.