CRACK TIP PARAMETERS AND ELASTIC-PLASTIC FRACTURE OF METALS

By using optical displacement-measuring techniques we obtain the crack tip fields in terms of crack tip strain, crack opening angle (COA) and crack tip opening angle (CTOA). Thin plates with different crack configurations made of six elastic-plastic materials with strain hardening exponent ranging from 3 to ∞ are studied. We find that the COA resistance curve assumes certain characteristics common to all the materials. The experimental results indicate that the critical value of COA may be used as a fracture toughness parameter for these materials. © 1990 Kluwer Academic Publishers.