Plastic mismatch effect on plasticity induced crack closure: Fatigue crack propagation perpendicularly across a plastically mismatched interface

Abstract

In the present work, comprehensive investigation of both theoretical analysis and numerical simulation was carried out to investigate the plastic mismatch effect on plasticity induced crack closure (PICC) behavior and effective fatigue crack tip driving force. During the process of crack tip approaching interface, crack tip load and crack tip load ratio will change, resulting in the change of PICC degree. When the crack propagates towards higher strength side, Kop/Kmax increases; when the crack propagates towards lower strength side, Kop/Kmax decreases firstly and then increases. The two mechanisms of “interface plastic mismatch effect on nominal fatigue crack tip driving force” and “interface plastic mismatch effect on PICC degree” were compared. The second mechanism must be considered when building crack tip driving force model for describing fatigue crack crossing plastically mismatched interface, because it is more physically factual and maybe more important than the first mechanism.

Novel Characterizations of Effective SIFs and Fatigue Crack Propagation Rate of Welded Rail Steel Using DIC

“…The classical Paris model does not consider the effect of the crack-tip plasticity-induced crack closure effect, and it is still an international academic issue to accurately characterize the effective stress-intensity factor ∆K eff under consideration for the crack-tip plasticity-induced crack closure effect. At present, research on the effect of plasticity-induced crack closure locally and abroad mainly includes both numerical simulation [3][4][5] and experimental methods [6][7][8]. Among the experimental methods, DIC technology is a noncontact, high-precision method for full-field displacement, deformation, and stress measurement, which is increasingly used in various fields because of its extremely relaxed test environment requirements and its advantages of full-field measurement, strong anti-interference ability, and high measurement accuracy.…”

Crack closure in friction stir weldment using non‐linear model for fatigue crack propagation

“…In their studies, these researchers have used a range of methods from a simple tensile loaded plate to more complex structural components under both uniaxial and mixed‐mode loading conditions. Huffman, Shi et al, Kujawski and Ellyin, Li et al, Noroozi et al, Song et al, Tong et al, and Akhtar et al are some of the researchers who have studied the fatigue behaviour of cracked components under uniaxial or multiaxial non‐linear loading conditions. In some cases, the effect of the mean stress on the fatigue crack behaviour was also assessed.…”