Creep-fatigue crack growth behavior under mean stress effect in polymer electrolyte membrane: Experimental analysis and numerical crack growth modeling

The creep-fatigue crack growth behavior of polymer electrolyte membrane under cyclic loading with distinct mean stress is investigated. The crack under cyclic loading with higher mean stress displays enhanced propagation rate. Identical cyclic plastic zone size is found under different stress ratios, implying that the fatigue damage primarily depends on stress amplitude. The creep damage leads to the occurrence of crack-front micropores, thereby accelerating crack growth. The enlargement of hydrophobic domain is detected at high stress ratio, which reveals the creep effect on failure process from phase morphology aspect. A damage-based numerical model is established to predict creep-fatigue crack growth.