The fatigue crack growth mechanisms in polymer electrolyte membranes of fuel cell are investigated under single overload conditions. In-situ SEM testing and in-situ optical microscopy testing combined with digital image correlation technique are conducted. The results show that the residual stress dominates the fatigue crack growth after the application of small overload cycle leading to subsequent fatigue crack growth retardation while larger overload cycle causes crack tip sharpening, resulting in fatigue crack growth retardation reduction or even acceleration.
EXTENDED ABSTRACT