Analytical modelling of the influence of local mixed mode displacements on roughness induced crack closure

Abstract

Application of crack closure analytical modelling to predict the behaviour of complex fatigue crack growth properties is limited partly due to restricted two dimensional modelling approaches. An analytical model of roughness induced crack closure (RICC) is developed in the present paper considering a three dimensional twisted and kinked crack path. Residual shear deformations at asperities in the crack wake affect the crack opening generating closure. These residual shear deformations are explicitly formulated from 1 residual plastic deformation. The respective influence of the in-plane and out-of-plane deformation on RICC is discussed. The crack twisting is found to be a less significant effect on the RICC than the crack kinking, for similar deviation angles. However, these out-of-plane crack deflections are found to be non negligible particularly at low tilting angles. This analytical model is used to predict the closure stress intensity factor for a range of 2xxx aluminium alloys. Predictions are compared to experimental results obtained from low ΔK fatigue crack growth tests. Experimental results show that fatigue performance scale with closure level and roughness of the failed fatigue specimen surfaces. Comparison of estimated and measured closure stress intensity factor show similar trends.

Effects of heating rate during solid-solution treatment on microstructure and fatigue properties of AA2524 T3 Al–Cu–Mg sheet

“…13f). The phenomenon of crack closure delaying fatigue crack propagation has been observed and reported in the previous studies as well [34,35]. Thus, the crack closure observed in this study may be related to the high Schmid factors and large sizes of the grains, as per the statistical chart of the Schmid factors (see in Fig.…”

Texture effect on fatigue crack propagation in aluminium alloys: An overview

“…On the other hand, various studies have reported that the fatigue crack growth behaviour of aluminium alloys is affected by crack closure effect, particularly near-threshold region [43,44]. Besides, the crack closure effect is greatly influenced by grain size, deflected angle and slip bands [45,46].…”

Thermal activation of fatigue crack growth: Analysing the mechanisms of fatigue crack propagation in superalloys

“…One further thermally activated process influencing FCG rates is crack closure [1,54], most notably oxidation induced crack closure (OICC). OICC can become important if the exposure of surfaces to the environment in the wake of the crack leads to (additional) oxidation that causes a substantial volume expansion.…”