Effect of the mesh size of the vector displacement field on the strain estimate in the digital image correlation method

The influence of the mesh size of the displacement vector field on the strain estimate in the digital image correlation method is considered. The reasons for the emergence and the magnitude of the strain estimate error in processing optical images of material surfaces with different textures are analyzed. The dependence of the mesh size for strain estimation on the magnitude of displacements and also on the presence and size of the discontinuity region in the strain field is studied. An adaptive algorithm for choosing the mesh size is proposed, which allows the strain calculation error to be reduced by a factor of 1.9 with simultaneous reduction of computational expenses by a factor of 2.1.     

Plastic deformation and fracture caused by coating-substrate mismatch at mesoscale

A large amount of experimental data obtained from the television-optical measurement technique (TOMSC) have been analyzed to identify the main mechanisms of plastic deformation at the mesoscale level for coated and surface-hardened materials. Among the factors to be concerned are the site of nucleation and relaxation of mesostress concentrators, the geometry and interface structure of which can influence the outcome.     

Plastic deformation and fracture of polycrystalline Ni–Ti with stress concentrators of different scales

Stress concentrators of different scales inherent in polycrystals tend to form mesosubstructures under load. Television-optical images of displacements are obtained for the Ni–Ti alloy to study the deformation and fracture behavior. Discussed are similarity laws in connection with the formation of dissipative structures at the micro- and macro-scale level.