Failure of granite cylinders under impact loading

The temporal variation of axial and radial particle velocity components on the surface of granite cylinders was measured when the latter were struck on end by like cylinders of equal diameter. The experimental results were compared with two-dimensional axisymmetric finite difference calculations in which several different constitutive models were evaluated. Fairly good agreement with experiment was obtained with a simple intuitive representation of the brittle fracture process in which locally linear elastic behavior prevailed until such time as any principal stress component exceeded in tension some small prescribed value. The subsequent failure mechanism admits the opening of cracks, multiple cracking to the point of pulverization and possible reclosure under polyaxial compression. The fracture zone development is strongly influenced by a feedback effect from the interaction of the elastic field in the virgin material with signals propagating forward from the existing fracture zone.