Elastic-Plastic Analysis for Cracked Members

Elastic-plastic finite element analyses are performed for cracked specimens of various geometries and material properties. The calculations are based on the small strain, J₂-deformation theory of plasticity; employing a power hardening model for the material behavior under uniaxial tensile loading. The finite element procedure includes the use of a specialized plastic, crack tip singularity element; and, it is applicable to the geometric idealizations of plane stress, plane strain, and axial symmetry. Results are presented for tensile and bending specimens containing exterior cracks and for a hollow cylindrical specimen with a circumferential crack subjected to tensile and pressure loading. Numerical values are reported for the plastic intensity factor, the crack face separation at the exterior surface, and the J-integral. Both the implications of these results to fracture prediction and the limitations on their applicability as a consequence of geometric and material modeling idealizations are discussed.