Unexpected, mystifying but simple three-dimensional dynamic fracture phenomena

This contribution addresses what can be learnt from our recent experimental observations of dynamic fracture development in brittle solid materials with real three-dimensional configurations. It is pointed out that the three-dimensional dynamic behaviour of (quasi-)brittle solids is essentially different not only from the one-dimensional dynamic one but also from the three-dimensional static one. The experimental observations include those of cylindrical concrete columns pressurized by deflagration at the centre and ice spheres subjected to dynamic impact at the bottom. Surprisingly, plain fracture patterns can be found through these experiments, but it does not seem simple to describe or predict the involved physical process by conventional analytical treatment or numerical simulations. Indeed, our understanding of mechanical details of actual three-dimensional fracture is still limited, especially in dynamic cases where the length scale of fracture and relevant waves is of the order of the size of solids under consideration. Although a more sophisticated physical interpretation including the dynamic interaction of waves in a relatively high-frequency range is required, the discussed dynamics of three-dimensional fracture development will assist in generating precisely controlled dynamic fracture networks that can be used for practical purposes of dismantling solid structural components and mitigating risks of catastrophic failures. This article is part of the theme issue ‘Fracture dynamics of solid materials: from particles to the globe’.