An entropy-based model of plastic deformation energy dissipation in sliding.

In order to study the individual energy dissipation mechanisms which act in plastic deformation in sliding, an entropy production model of the sliding process is constructed. Rather than a physical material body, the system considered is a geometric space in which metallic lattice defects can exist. This system can interact with its environment which is the space of annihalated defects. In this system model energy dissipation through structural changes caused by defect creation and heat generation due to defect annihilation are included. For a behaviour in which the defect annihilation rate is exponentially dependent on temperature, the minimum entropy production rate system evolution criterion predicts the existence of two different stationary entropy production rate states. In one state entropy production is dominated by structural changes and in the other by heat generation. Changes from one of these states to the other during sliding may account for the formation of a varying sliding body microstructure along the sliding direction. (A)