Numerical predictions of the negative phase

The field of blast protective design emerged in the late 1940s and focussed mainly on large scale (nuclear) explosive loading massive structures. In these situations, positive phase effects were seen to dominate and the negative phase could effectively be ignored. Recently, however, the threat has moved to smaller scale explosives and increasingly lightweight structures. Here, the negative phase becomes important, however despite this the negative phase is often overlooked. This research presents a numerical investigation on the negative phase, with a primary focus on an accurate numerical scheme for modelling the negative phase blast pressure. Numerical tests are performed on deformable targets to determine fully reflected blast parameters, with associated numerical modelling conducted using Abaqus/Explicit. Moreover, the failure modes are obtained for light-weight panel employing the Perzyna model for metallic materials. The computational methods are adapted for better representation of the negative phase, including mesh refinement strategies, modelling of the explosive event and accurate description of the air behaviour. The results herein can be used to inform blast resistant designers on how to accurately model negative phase effects.