Finite element simulation of elastoplastic field near crack tips and results for a central cracked plate of LE-LHP material under tension

Abstract

The elastoplastic field near crack tips is investigated through finite element simulation. A refined mesh model near the crack tip is proposed. In the mesh refining area, element size continuously varies from the nanometer scale to the micrometer scale and the millimeter scale. Graphics of the plastic zone, the crack tip blunting, and the deformed crack tip elements are given in the paper. Based on the curves of stress and plastic strain, closely near the crack tip, the stress singularity index and the stress intensity factor, as well as the plastic strain singularity index and the plastic strain intensity factor are determined. The stress and plastic strain singular index vary with the load, while the dimensions of the stress and the plastic strain intensity factors depend on the stress and the plastic strain singularity index, respectively. The singular field near the elastoplastic crack tip is characterized by the stress singularity index and the stress intensity factor, or alternatively the plastic strain singularity index and the plastic strain intensity factor. At the end of the paper, following Irwin’s concept of fracture mechanics, $$\sigma_{\delta K}$$ criterion and $$\varepsilon_{\delta Q}$$ criterion are proposed. Besides, crack tip angle criterion is also presented.