Elastic-plastic fracture behavior of an aluminum alloy under mixed mode conditions

Abstract

Mixed mode (Mode I+II) elastic-plastic fracture tests were conducted using A5083-0 aluminum alloy compact-tension-shear specimens. The behaviors of crack tip blunting and crack growth were studied by fractographic investigation. Mixed mode loadings were found to cause a blunting of one corner of the crack tip and a sharpening of the other corner. Under a load with relatively high mode II components, a fracture by shear localization initiated at the sharpened corner of the crack tip near the surfaces of the specimen, and then another fracture by microvoid coalescence occurred at the blunted corner of the crack tip near the midthickness of the specimen. This was explained qualitatively by taking into account of the stress and strain singularities and the triaxial stresses near the surface and the midthickness of the specimen. Fracture mechanics parameters appropriate for mixed mode elastic-plastic fractures were also studied based on the experimental data. © 1990, The Japan Society of Mechanical Engineers. All rights reserved.