Experimental Estimation of Mixed Mode I/II Fracture Toughness of SE(B) Specimen of Aluminum Alloys

This paper aims at characterizing the mixed mode fracture behavior of Aluminum bend specimens of grades 5083 and 7075 with single edge cracks. The principle of this test method is based on loading at an eccentric location from the crack tip so that the components of the load make the crack to grow in a Mixed-mode I/II. Unloading compliance technique is used to determine mixed mode Jresistance curves for SE (B) fracture specimens. Laboratory testing of 5083 and 7075 grade aluminum alloys at room temperature using SE(B) specimens with eccentric loads provide the load-displacement data needed to estimate the mixed mode crack growth resistance curve for the material. The results presented here produce a representative set of fracture toughness for mixed mode SE(B). The J-resistance curves for symmetric and unsymmetric loading conditions are compared with finite element analysis results. This shows the load eccentricity method proposed here sounds a viable method to calculate mixed mode J-R curves. Forces are analyzed to separate the mixed mode fracture toughness into mode I and mode II fracture toughness.