MAXIMUM ENERGY-RELEASE RATE DISTRIBUTION FROM A GENERALIZED 3D-VIRTUAL CRACK EXTENSION METHOD

This paper presents a generalized 3D virtual crack extension (VCE) technique for determining the distribution of the maximum energy release rate along a general 3D crack front. The method allows for VCEs at any inclination to the local crack plane. By taking the component of the extension in the crack front's local normal plane it evaluates the local energy release rate, G, in that component's direction. Repeated VCEs applied to the crack front at different inclinations enable the maximum G and its associated direction in the normal plane to be determined. This technique has been applied to a quarter-circular crack in a square cross-section bar under axial and torsional loading. The evaluated maximum energy release rates show the expected antisymmetric direction and symmetric magnitude distributions. The test case also demonstrates a sinusoidal G distribution within the normal plane which would imply that the maximum G and its direction could be evaluated from only two local G values.