An approach to prediction of microstructure formation near friction surfaces at large plastic strains

The paper develops an approach to formulation of constitutive equations for predicting the microstructure formation in a thin material layer near surfaces with high friction stresses in material forming processes. The approach is based on the use of the strain rate intensity factor. An equation relating the layer thickness to the strain rate intensity factor is proposed. A similarity condition that provides the same layer thickness at appropriate friction surface points in full-scale and model experiments is derived. The condition implies that the degree of strain inhomogeneity and hence the degree of inhomogeneity of material properties depends on the scale factor. As an example, compression of a thin layer between parallel plates is considered. Assuming validity of the proposed equation, a relationship is established between the parameters of compression and the layer thickness with essentially changed microstructure.