Mixed mode fracture criteria for ductile materials

摘要

This paper presents an investigation of examining the applicability and accuracy of two fracture criteria proposed for the prediction of crack initiation angle for ductile materials using the strain energy density approach. One criterion is based on the hypothesis that the angle of crack initiation is governed by the maximum value of minimum strain energy density, (dW/dV){sub}min, stored in an element ahead of the crack tip. Another hypothesis has recently been proposed postulating that themaximum value of dilatational energy (dW/dV){sub}V{sup}max, determines the crack growth direction for ductile materials.The investigation involves both analytical and experimental analyses of determining crack initiation angles of thin plates of aluminium alloy 2024-T3 embedded with an inclined crack angle ofβ= 30, 45, 60, 75 and 90 degrees. The results reveal that bothfracture criteria predict satisfactorily the angle of crack initiation in ductile materials under mixed mode loading hut the criterion based on (dW/dV){sub}v{sup}max appears to yield in general more accurate prediction than that of(dW/dV){sub}min{sub}max.