On the dominant role of crack closure on fatigue crack growth modeling

AbstractCrack closure is the most used mechanism to model thickness and load interaction effects on fatigue crack propagation. Butassuming it is the only mechanism is equivalent to suppose that the rate of fatigue crack growth da/dN is primarily dependent on K eff =K max K op , not on K. But this assumption would imply that the normal practice of using da/dN× K curves measuredunder plane-stress conditions (without considering crack closure) to predict the fatigue life of components working under plane-strain could lead to highly non-conservative errors, because the expected fatigue life of “thin” (plane-stress dominated) structurescould be much higher than the life of “thick” (plane-strain dominated) ones, when both work under the same stress intensity rangeand load ratio. However, crack closure cannot be used to explain the overload-induced retardation effects found in this work underplane-strain, where both crack arrest and delays were associated to anincrease in K eff . These results indicate that the dominantrole of crack closure in the modeling of fatigue crack growth should be reviewed.2003 Elsevier Ltd. All rights reserved.