O-067 A Proposed Amendment to the Critical Energy Criterion for Numerical Modellers: the Critical Power Criterion

Different techniques have been developed and used to predict the conditions for initiation of detonation of an explosive subjected to shock. The Critical Energy Criterion is the most well known. The concept has been improved by various authors to describe critical initiation conditions when the shock is induced by different shaped projectiles.

However, this modified Walker and Wasley Criterion has its limits of applicability. We have proposed an amendment to the Critical Energy Criterion taking into account he rate at which energy is deposited in the explosive, i.e. the power input. Experimental data on bare and covered explosive initiation thresholds for plate or sphere impacts are in good agreement with LS Dyna-2D simulations and data obtained using this amendment.

This explains why it is not possible to translate shock sensitivity gap test data from site to site, because of the use of different donor explosives and barrier materials, which generate different ramp and peak pressures on the receptor explosives being tested.