STRAIN-RATE EFFECT ON BRITTLE FAILURE IN COMPRESSION

A simple model of an array of interacting, dynamically growing wing cracks is used to simulate the rate-dependent dynamic damage evolution and subsequent brittle failure of solids under compression. The validity of the model is discussed. Parameters which identify the overall failure by the coalescence of compression-induced, interacting, tensile microcracks are calculated in closed form, and relations between microstructure and the corresponding rate dependency of the overall response are examined in some detail. It is shown that the experimentally observed change in the compressive failure stress with increasing strain rate, may be considered to be a consequence of the generation and dynamic growth of interacting, compression-induced, tensile microcracks. Examples of brittle failure in uniaxial stress and uniaxial strain conditions, respectively, produced in the Hopkinson compression bar and normal plate-impact experiments, are discussed in terms of this model.