An improved crack-tip element treatment for advanced FEMs

Abstract This paper presents an improved treatment for those advanced FEMs that use stresses in the crack-tip element for evaluation crack propagation condition. We show that the common treatment of obtaining crack-tip displacements using simple interpolation from the edge of the crack-tip element is inaccurate and is responsible for the jagged jump and unwarping behavior (JJU) frequently reported in literature. In this study we propose a more accurate treatment by introducing an element node with independent degree of freedom (DoF) to enrich the crack-tip element. We show that the proposed approach can relieve the stiffness overestimation of the crack-tip element without disrupting the standard element interpolation process. Results of numerical examples demonstrate that the improved treatment can greatly improve the stress shielding phenomenon and effectively reduce the JJU in load-displacement curves.