Crack growth under biaxial compression

An experimental and analytical investigation into three-dimensional crack growth under biaxial compression is presented. Tests were carried out on different materials, including transparent resin samples, each with a single embedded disk-like crack. These cracks grew extensively parallel to the load directions causing splitting. This behaviour is markedly different from that observed under uniaxial compression where the crack growth is limited in size, and is not capable on its own to induce failure. The presence of the intermediate principal compressive stress radically changes the mechanism of crack growth. A model is proposed where the growing crack is represented as a disk-like crack oriented parallel to the loading direction and opened by a pair of concentrated forces at its centre. It is shown that the crack growth is stable until it reaches a size comparable to its distance from the free surface.