پیش بینی های رشد خستگی بر اساس تجمع آسیب پیش از نوک کرک محاسبه شده توسط روش های عملکرد نوار

Elber assumed a long time ago that ΔKeff is the driving force for fatigue crack growth (FCG), and his hypothesis is the basis for strip-yield models widely used to predict residual lives of cracked components. However, this hypothesis cannot explain many load sequence effects observed in practice. Hence, it is at least worth to verify if FCG models based on ΔKeff are indeed intrinsically better than concurrent models based on other principles. To do so, the same mechanics is used to predict FCG rates based both on Elber's ideas and on the alternative view that FCG is instead due to damage accumulation caused by the cyclic strain history ahead of the crack tip, an idea does not need or use the ΔKeff hypothesis. To compare both approaches fairly, FCG rates are estimated by damage accumulation using the cyclic strain ranges induced by plastic displacements calculated by the very same procedures used by strip-yield models, assuming there are strain limits associated both with FCG thresholds and with material toughness. Despite based on apparently conflicting principles, both models can reproduce quite well FCG curves, a somewhat surprising result. Besides confirming that data fitting cannot be used to prove any model superiority, this result indicates that the ΔKeff hypothesis is not a necessary requirement to explain the FCG behavior.