Propagation of semi-elliptical crack in pin-lug joint

Pin-lug joints are commonly employed to connect components related to several mechanical applications in aeronautic, marine and automotive fields. The load transferred by the pin to the lug, through the contact along the hole edge, generates high local stress concentration that may produce initiation of cracks from local imperfections along the bore of the hole, and such cracks may propagate up to failure. In the present paper, the fatigue crack growth simulation of a semi-elliptical crack located at the midway along the hole bore of an attachment lug is carried out by employing a simplified model based on the Paris law. The Stress Intensity Factors along the crack front are numerically determined through finite element analyses. The geometry, sizes and loading conditions are chosen in order to simulate some experimental fatigue tests related to lugs made of PolyMethylMethAcrylate (PMMA) subjected to remote cyclic tension. The experimental data are employed to validate the simplified model by comparing the results in terms of relative crack depth and crack front evolution.