Sequential determination of dynamic initiation and propagation toughness of rock using an experimental-numerical-analytical method

We propose the use of an experimental-numerical-analytical method to determine the dynamic initiation and propagation toughness of rock. The specimen adopted is the cracked straight-through flattened Brazilian disc diametrically impacted by a split Hopkinson pressure bar. The crack initiation moment and crack propagation velocity were sequentially measured with a crack propagation gauge glued in front of the specimen's crack tip. Dynamic stress intensity factor histories were obtained by finite element analysis, with inputs of the dynamic loading histories recorded in the experiment. In determining the dynamic propagation toughness, the effect of the crack propagation velocity on the dynamic stress intensity factor was taken into account analytically, by applying the universal function (Freund, 1990).