Multi-parameter fracture criteria for the estimation of crack propagation direction applied to a mixed-mode geometry

•The kink angle of a crack in a geometry was studied for a range of mode mixities.•Maximum tangential stress and minimum strain energy density criteria were applied.•A multi-parameter form of the criteria (using the Williams expansion) was tested.•The influence of higher order terms of the series is significant in specific cases.•The results are important when more complex nonlinear fracture tasks are solved.

A parametric study has been performed on an eccentric asymmetric four-point bending specimen in order to investigate initial crack propagation direction. Under various levels of mixed-mode conditions, the generalized form of the maximum tangential stress criterion and the strain energy density criterion has been derived by means of the multi-parameter description of the crack-tip stress field. A discussion on the need to consider several more initial terms of the Williams expansion during fracture behaviour assessment is presented and some recommendations are stated based on the results of the analyses.