Abstract: The FEM analyses and experimental results showed that the stress triaxiality in the crack tip regions of bend specimens with different crack depths vary with each other and are unable to meet the constraint intensity required by HRR solution is the principal reason leading to the losing of J-dominance and the dependence of Ji-value on the crack-depth, which is no longer a material constant. A new elastic-plastic fracture criterion Jvi=Jif (vσm/σ) at initiation has been proposed and proven to be a material constant independent from crack-depth by experimental results presented.

Key words: 裂纹深度, 启裂准则, 应力三轴性, 主导参数