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

• Published in: International journal of fatigue 2003-09, Vol.25 (9), p.843-854
• Main Authors: Meggiolaro, Marco Antonio, de Castro, Jaime Tupiassú Pinho
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Crack closure; Exact sciences and technology; Fatigue crack growth; Fatigue, brittleness, fracture, and cracks; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Metals. Metallurgy; Physics; Sequence effects; Thickness effect
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/S0142-1123(03)00132-4

Crack closure is the most used mechanism to model thickness and load interaction effects on fatigue crack propagation. But assuming it is the only mechanism is equivalent to suppose that the rate of fatigue crack growth d a/d N is primarily dependent on Δ K eff= K max− K op, not on Δ K. But this assumption would imply that the normal practice of using d a/d N×Δ K curves measured under 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) structures could be much higher than the life of “thick” (plane-strain dominated) ones, when both work under the same stress intensity range and load ratio. However, crack closure cannot be used to explain the overload-induced retardation effects found in this work under plane-strain, where both crack arrest and delays were associated to an increase in Δ K eff. These results indicate that the dominant role of crack closure in the modeling of fatigue crack growth should be reviewed.