Fatigue Life Extension by Crack Repair Using Stop-hole Technique under Pure Mode-I and Pure mode-II Loading Conditions

Drilling a hole at the crack tip turns the crack into a notch and diminishes the crack tip stress singularity. In this paper, the crack growth retardation is examined using a numerical study on the efficiency of stop holes. Pure mode-I and pure mode-II loading conditions have been generated by using the mixed mode compact tension specimen made of 6061-T651 aluminum alloy. A fatigue crack growth code developed for two-dimensional elastic problems is used to validate the numerical procedure. The numerical results reveal that the presence of stop holes significantly decreases the stress concentration around the crack tip. The fatigue life extensions and the location of fatigue crack initiation from the hole edge are studied under different loading conditions. A comparison between the reported experimental results and the obtained computational results shows that the fatigue life extension caused by the stop-hole method can be well predicted by the numerical model developed in this study.