Study of Dislocation Failure Phenomena in Uniform Radial and Tensile Fields

摘要

In this report two states of plane elastic dislocation were studied. In one, dislocation patterns were the result of uniform radial stress fields. In another, the dislocation cuts appear in a uni-axial stress field. The uni-axial stress field yields a predetermined pattern of dislocation cuts. But the radial stress field produces dislocation patterns more or less of a random order. The model of the radial stress field problem is a large plate bounded at the interior by a circular hole. The model is subjected to a load that produces a uniform, radial tensile stress field with respect to the center of the hole, while the edge of the hole remains traction free. According to theoretical analysis and verified by experiments, the maximum shear occurs at the edge of the hole. Upon certain critical loads, the model yields by formation of Lueders bands. The purpose in this report is to study qualitatively the Lueders band pattern and to observe any regularity of its formation.