In this dissertation, plastic deformation of friction surfaces under high energy input is investigated. The plastic deformation of the friction surface and subsurface was studied and models were established to estimate deformation.;In order to calculate the plastic deformation at friction surface, an algorithm based on Ramberg-Osgood relationship was generated, and a single material model was developed based on this algorithm. Work hardening caused by plastic deformation and thermal softening caused by elevated temperature were considered in the model. To validate the model, an apparatus was designed to perform friction tests under different conditions. A special steel specimen with a copper insert was prepared. A single material model was validated by the test results.;Friction materials are the composites of matrix materials, reinforcement particles, abrasive particles and lubricants. Effects of additives on plastic deformation are different. Single additive particle models were built based on the single material model to study the effect of additives on the plastic deformation of the matrix material. The most common additives, graphite and silicon were investigated. Specimen with a single additive particle were fabricated and tested. The single additive particle models were compared to experiment results. Simulation models for more complicated situations were discussed.;The research in this dissertation provides a mechanism to study complex friction materials, and provides a new method for friction material study. The models are convenient tools that could be used to study the friction mechanisms and improve the performance of friction material.
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