Use of fracture mechanics to predict fatigue initiation life under multiaxial loading conditions

✍ Scribed by Y Wang; J Pan

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 184 KB
• Volume: 21
• Category: Article
• ISSN: 0142-1123
• DOI: 10.1016/s0142-1123(99)00069-9

✦ Synopsis

Small shallow surface (Case A) cracks in power-law strain hardening materials are investigated under plane stress, general yielding, and mixed mode I and II conditions by finite element analyses. The trend of constant J contours on the ⌫-plane for Case A cracks from the computational results compared well with those of constant fatigue life and constant crack growth rate contours obtained from experiments. The effects of the transverse strain (the normal strain in the crack-line direction) on the near-tip fields of small Case A cracks in power-law strain hardening materials are also investigated by finite element analyses. The results suggest that the fatigue life prediction based on multiaxial fatigue theories and the critical plane approach should include the constraint effects due to the transverse strain. Consequently, a damage parameter as a function of the shear strain and two normal strains is proposed for evaluation of Case A fatigue damage under multiaxial loading conditions. In addition, the near-tip fields of small deep edge (Case B) cracks in power-law strain hardening materials are investigated under generalized plane strain, general yielding, mixed mode I and II conditions by finite element analyses. The trends of constant J contours on the ⌫-plane for Case B cracks from the computational results are compared reasonably well with those of constant fatigue life contours obtained from experiments.