Crack Initiation Predictions of the AFM-Specimen under Bend and Torsion Loading

Abstract

In this paper, the computational predictions of crack initial breakpoint and deflection angles under bend and torsion loading conditions are investigated in conjunction with the modified virtual crack closure integral (MVCCI)-method by using the all fracture modes (AFM) specimen and commercial software ANSYS. The separated strain energy release rates (SERRs) along the crack front are calculated and subsequently converted to the stress intensity factors (SIFs) by using Irwin´s equations. Based on the SIFs results, the crack initiation predictions are presented by the maximum principal stress σ1'-criterion. Results show that when the AFM-model under a series of combined proportional bend and torsion loading conditions, asymmetrical stress fields are produced along the crack front. The presented investigation also shows that the maximum principal stress σ1'-criterion in conjunction with the MVCCI-method provides a powerful numerical tool for general computational approach to the fracture analysis of complex loading conditions.