Plasticity

A plastic analysis of a cracked body may be carried out by generating a cracked mesh with appropriate material definitions and analysis controls. This allows the development of plasticity to be studied in a cracked component.

For linear elastic analysis the recommended method of modelling a defect is to use collapsed brick elements with a single node at each crack front point. For 20 noded elements the radial nodes are moved to the quarter-point position. For a plastic analysis the effect of blunting and the modified singularity is usually studied by using multiple nodes at each crack front position with radial midside nodes left at their midside positions. Meshes with these types of crack tip modelling are readily generated in Zencrack by using the option *TIP MODE, TYPE=LEFM or *TIP MODEL, TYPE=EPFM respectively.

Crack tip model for LEFM

Crack tip model for EPFM