Experimental investigations of the influence of thickness and mixed mode loading on the crack initial angle in LC4-CS aluminum

The influence of thickness and mixed mode I/II loading on the crack initial angle of aluminum LC4-CS plates of 2, 4, 8 and 14 mm. thickness was investigated experimentally from tensile-tearing testing of the compact-tension-shear type specimens. Experimental results of the crack initial angle for various thickness plates and load mode mixity were presented, and compared with theoretical predictions from the maximum tangential stress criterion and the maximum triaxial stress criterion. The crack initial angle is found to vary not only with load mode mixity but also with specimen thickness. The experimental results show a good agreement with theoretical predictions in 2, 14 mm-thickness specimens but a great deal difference in 8 mm-thickness specimens.,The results are discussed in the viewpoint of three-dimensional failure theory.