Controlled fracture of brittle solid materials based on wave dynamics

Abstract

It is critically important to establish controllable fracturing techniques for safer and more effective operation in disintegration (or partial removal) of complex structures made of solid materials. Therefore, we have been developing more precise methods for controlled dynamic fracture of brittle solid materials based on the theory of wave dynamics that takes into account the influence of wave propagation and interaction with inhomogeneities such as free surfaces, interfaces and e.g. reinforcing steel bars in concrete. For this aim, instead of explosives, using more easily handleable electric discharge impulses, we have experimentally investigated optimal geometrical and dynamic loading conditions for fracture of a given structure in the field. Comprehensive experimental observations with a high-speed digital video camera and computations by our fully three-dimensional finite difference simulator have indicated that crack development in brittle solid materials may be governed by the combination of direct waves from blast holes (energy sources) and reflected / diffracted ones. Here, we show especially that sets of blast holes surrounded or sandwiched by empty dummy holes may indeed control the dynamics of waves (and thus main crack propagation and final disintegration pattern) in rectangular concrete structures, even when all blast holes are simultaneously pressurized and waves are radiated from all energy sources concurrently. The technique mentioned in this work may be employed to actualize not only crack extension in a desired direction but also rather precisely controlled dynamic fracture of (parts of) brittle solid materials.