Energy-Release Rate and Crack Kinking Under Combined Loading

Abstract

Based on the maximum energy-release-rate criterion, kinking from a straight crack is investigated under the plane strain condition. Solutions are obtained by the method that models a kink as a continuous distribution of edge dislocations. The energy-release rate is expressed as a quadratic form of the stress-intensity factors that exist prior to the onset of kinking, and the coefficients of this quadratic form are tabulated for various values of the kink angle. The examination of the results shows that Irwin’s formula for the energy-release rate remains valid for any kink angle provided that the stress-intensity factors in the formula are taken equal to those existing at the tip of a vanishingly small kink.