Effects of Plate Thickness on the Fatigue Crack Propagation Paths of Pure Aluminum Plates with Unique Anisotropy

摘要

Fatigue crack of pure aluminum plates with unique anisotropy propagated to rolling direction that made 30° to loading direction. The crack propagated as a mixed mode I + II crack. Effects of plate thickness to fatigue crack were observed by conducting fatigue test on CCT specimens with thickness of 0.8 mm, 1.5 mm and 2.5 mm. The stress intensity factor of the crack was analyzed with Finite Element Method (FEM) using the displacement extrapolation method. As the result, the crack starts to grow to rolling direction as △K{sub}(total) = 5～8 MPa·mm{sup}(1/2). It is also confirmed that the thicker plates cause the smaller monotonic plastic zone size r{sub}p on the crack tip. It leads to near plane-strain condition on the crack tip and the crack grows easier to rolling direction.