Experimental study of the deformation near a notch tip in copper and copper-beryllium single crystals

The plastic deformation around a notch tip within ductile single crystal material was investigated experimentally. Moiré microscopy was used to measure the strain field on the surface of bending samples of Orientation II with a notch on the (010) plane and its tip along the [1̄01] direction. The results of tests conducted on copper and copper-beryllium single crystals are compared to analytical solutions, numerical calculations, and prior experiments on samples of Orientation I with a notch on the (101) plane and its tip along the [101̄] direction. Distinct sectors with sharp sector boundaries are observed in experiments as were predicted analytically by Rice (Mech. Mater. 6 (1987) 301). However, Rice predicted that both Orientations I and II would give rise to the same sectors. It is found that experimental results for these two orientations differ and neither set of results agree with the analytical solution. In both orientations, the sector boundaries do not exclusively correspond to angles at which slip and kink can occur in these crystallographic orientations. The experiments also lead to the conclusion that some sectors in the deformation field remain elastic even after large amounts of deformation have occurred elsewhere. Based on the optical observations and strain measurements, a stress field is presented for Orientation II.