A Plasticity Criterion for Mixed Mode Fracture Initiation with Crack Surface Frictional Characteristics Under Compression

ABSTRACT

A new plasticity criterion for mixed mode crack initiation angles under compression is presented, based on the characteristics of the plastic core region surrounding the crack tip with crack surface friction. The shape and size of the plastic core region were thoroughly analyzed under compression and the non-dimensional variable radius of the plastic core region for mixed mode compressive fracture was considered. Obviously, the mixed mode fracture initiation under compression is influenced by the frictional characteristics of the crack surface and the external compressive loading state. The loading ratio, Poisson’s ratio and the influence of the friction coefficient on the crack tip plastic radius were analyzed. The proposed criterion shows that the crack extends in the direction of the global minimum of the plastic core region boundary. The presented criterion was simulated for various compressive loads and was compared, with other available criteria, against the laboratory experimental data. It can be seen that the presented criterion provides a better agreement with the experimental data.

Keywords:

Crack tip plasticity , mixed mode fracture , crack propagation , stress intensity factors , friction .