K_Ic Determination of a 7075 T6 Aluminum Alloy by Critical Distances Theory and LEFM

The Critical Distances Theory has been used in engineering field as a less expensive method to predict failures. Thus, this research aims to evaluate its methods in other materials, like the aluminum alloy 7075 T6, and notches. Two different notches were machined: a sharp and a blunted, with radius of 0,025 mm and 0,045 mm, respectively. The first in specimens of tests tension and the last in bend tests specimens. The DCT methods analyzed exhibited low percent differences and predictions mutually consistent. However, the Line Method stood out when presented 3% to percent difference. The analysis to stress field around of sharp notch tip, LM achieved a value of 12 MPa√m para K_Ic. Although, when these same results were applied in the Traditional Fracture Mechanics equations, a fracture toughness of 34 MPa√m was found. This last result is one of the best predictions achieved until the present moment in this research group. Mainly when compared with other works which determined the same property using the same thermal treatment conditions to this alloy.

Keywords:
Critical Distances Theory; AA 7075 T6 Aluminum Alloy; Artificial Aging; LEFM