Numerical Analysis of the Influence of Location of the Stop** Holes and their Diameter in the Crack Growth of Ductile Metals

Abstract

The fracture and crack gowth of mechanical structures is a usual phenomenon which is due to the application oftensile, cyclic loading or thermal stresses on the structure. So introducing ofmethods to prevent the crack growth is useful. Afterward, one of the repairing methods of crack gowth, consisting to make a hole in the crack tip to eliminate the s h q comers, was explained. This method is frequently used in air and space industly. The drilling can be done in various locations. Three locations in the crack tip for the hole is considered. They are showed in the Figure 1. In the frst, the hole is situated in the left of the crack tip (Location A). In the second one, it sits in the center of the crack tip (B) and in the last one; it sits in the right site of the crack tip (C). The study of resistance against crack growth is based on the comparison of these three systems. We have analyzed the influence of theses stop** holes, their diameters and their locations on the fracture toughness. The specimens are made of A1 7075-T6 alloy [1] and they have the shape of the Compact Tension specimen. The solicitation is a monotonic tensile loading in the mode I of Fracture. The Stress Intensity Factor and the critical load versus to the crack length of the test bars are computed. Numerical method is carried out bv fmite element method usine Ansvs software. Followine this numerical analysis, a fracture experimentation is carried out on the rensile machine to evaluate the influence of the stop** hole on the critical load of initiation of the crack growth. In result the best location of the hole increases 43% the critical load and the location which gives the weakest result shows 11% of increasing of the load. Thus in result of this research the best location of the stop** hole and its diameter are obtained to increase the life ofthe mechanical pieces.