Effect of Constraint and Crack Contact Closure on Fatigue Crack Mechanical Behavior of Specimen under Negative Loading Ratio by Finite Element Method

Abstract

Mechanical behaviors at fatigue crack tips of cracked specimens under negative loading ratios are studied in detail by the finite element method in this paper. Three factors induced by specimen type and loading type on fatigue crack field are discussed, including constraint, compressive loading effect (CL effect) and crack contact closure. For mode I crack under negative loading ratios, the effects of the CL effect and crack contact closure on plastic strain accumulations are dominant, with the constraint effect being minor. The constraint effect has effects on the monotonous plastic zone, while the CL effect and contact closure both have effects on the reversed plastic zone (RPZ) and residual tensile plastic zone (RTPZ). That is, the higher the constraint, the smaller the size of the monotonous plastic zone; the greater the CL effect, or the smaller the contact degree, the larger the size of RPZ and RTPZ. For mode II crack, there is only CL effect on the crack tip field without the effect of constraint and contact closure, so plastic strain accumulation at the mode II crack tip is much greater than that at the mode I crack tip when they are under the same loading level.

Study on Elastic Mixed Mode Fracture Behavior and II-III Coupling Effect

“…The mesh sensitivity of J-integral at the crack tip is shown in Table 2, which shows that the mesh size at the crack tip of 0.1 mm is accurate enough. Also, the above modeling methods have been applied to the study of mixed mode fatigue and the fracture of different materials [2,11,26]. that the fixture does not deform, the fixture adopts a rigid body.…”

Revisiting classical concepts of Linear Elastic Fracture Mechanics - Part I: The closing ‘mathematical’ crack in an infinite plate and the respective Stress Intensity Factors

“…From a completely different starting point (i.e., while seeking solutions for the problem of contact for an arc crack in terms of hypersingular integral equations), Chen et al [19], arrived at the conclusion that ignoring "…the contact effect for a contact arc crack, the obtained solution for the SIFs is of no sense". Nowadays, the above mentioned issues are usually (if not exclusively) studied by means of proper numerical schemes, which are based mainly on the Finite-and the Boundary-Element methods [20][21][22][23][24][25]. On the contrary, purely analytical solutions are relatively scarce in the respective literature [26].…”