FRACTURE AND FATIGUE ANALYSIS FOR A CRACKED CARABINER USING 3D FINITE ELEMENT SIMULATIONS

Fracture and fatigue behavior of a carabiner made of Al-7075 alloy and containing a small edge crack and subjected to a typical operational service load was studied numerically. Using several three dimensional finite element analyses, mixed mode fracture parameters of the cracked carabiner were computed for different crack geometries and various loading conditions. In the models, crack lengths, crack depths and crack inclination angles relative to the applied load were varied. Based on the obtained results, mode III deformation was negligible in the analyzed carabiner and thus its fracture would be mainly controlled by a mixed mode tensile-in plane shear fracture (mixed mode I/II) mechanism. Therefore, for each model the mode I and mode II stress intensity factors (K-I and K-II) and the T-stress were determined from finite element results. It was shown that the sign and magnitude of fracture parameters are significantly dependent on the geometry and orientation of crack. The critical crack depth and the remaining service life of the cracked carabiner subjected to repeated loading-unloading cycles were also computed numerically using the available fracture criteria and the fatigue crack growth models.