Non-linear Finite Element Analysis of Cracked A-517 Steel Compact Tension Specimens

Abstract

This manuscript describes the two-dimensional non-linear finite element analysis on compact tension specimens of A-517 structural steel. The numerical analysis enables us to study the behavior of crack in a typical ductile material under external loading. Local (or nodal) strain energy density at all nodes inside and outside the crack tip plastic zone at several external loads is numerically computed. In the expected crack propagation direction, i.e., 0 degree in compact tension specimens, the local strain energy density first decreases with increasing distance from crack tip but then at a critical distance it increases. This distinct behavior of the local strain energy density ahead of a crack is load dependent. The details of the numerical analysis are presented for a series of compact tension specimens having a wide range of crack length-to-width ratio (0.25 to 0.88). Based on our numerical results, we have proposed three parameters: (a) a critical load for the initiation of crack growth, (b) a crack length dependent local strain energy parameter associated with the initiation of crack growth, and (c) a material characteristic local strain energy parameter associated with the brittle fracture or plastic collapse of the ductile material.