Initiation and propagation of tensile wing cracks and horsetail cracks from a pre-existing flaw under compression

Abstract

Apart from the most commonly observed tensile wing cracks, horsetail cracks curving in a direction different from that of the tensile wing cracks are also observed initiated from the flaw tips. In the past, due to the convenience of analytical and numerical analyses, these two types of cracks were usually not differentiated. This paper examined the cracking processes of these two crack types, by using the non-linear dynamics hydrocode. The numerical study focused on the new cracks initiated from a pre-existing inclined flaw embedded in a rectangular specimen. The cracking model was based on the incorporation of the cumulative damage failure criterion and the Drucker-Prager strength model. The numerical results verified that tensile crack opening occurred along the tensile wing crack trajectory both in the elements adjacent to the pre-existing flaw and far away from the pre-existing flaw. In contrast, the horsetail crack was associated with a short shear crack segment adjacent to the flaw tip. Its remaining crack trajectory, which gradually curved towards the loading direction, was tensile in nature. © 2011 ARMA, American Rock Mechanics Association.