On the transition from adiabatic shear banding to fracture

摘要

Adiabatic shear banding is considered as one of failure modes. Few numerical studies were devoted to the investigation of the initiation and propagation of a ductile crack within an adiabatic shear band. In this paper, adiabatic shear banding is clearly separated from subsequent fracture. Both phenomena are handled separately in the present numerical simulation of an impact test on a modified axisymmetric hat specimen. The formation of adiabatic shear bands is automatically resolved using very fine meshes and the prediction of following cracks is achieved by means of a recently developed ductile fracture locus. The periodical occurrence of hot temperature spots within a propagating shear band is recreated in this modeling. It is found for the first time that these hot spots act as the initiation sites of a crack. In problems dominated by compression, unloading stress waves are mainly responsible for the formation and growth of the crack. Comparison with few existing experimental results is made showing good agreement.