Blast wave propagation in survival shelters: experimental analysis and numerical modelling

The propagation of blast and shock waves in confined environments is a complex phenomenon; yet, being able to derive valid predictions of such phenomena is highly relevant, for example, when it comes to the assessment of protection of personnel in military environments. This study looks at the propagation of blast waves inside a compound survival shelter. Experimental analyses are performed on a small-scale model of the actual configuration of the shelter subjected to the detonation of an explosive charge at different locations close to its entrance. Pressure-time signals are recorded on a number of locations in the model. A numerical model is also developed to complement the experimental programme, based on the explicit finite element (FE) code LS-DYNA. The recorded experimental data (e.g., pressure and impulse) are compared with the numerical predictions to validate the FE model. The authors discuss two different modelling approaches (the Lagrangian and the MM-ALE formulations) and analyse the influence of using a different number of ambient layers, the advection method, the time-step size, and level of discretisation. The proposed numerical model predicts and captures the relevant stages of the propagation of the shock wave very well, with error levels on the resulting specific impulse always lower than 19% when compared to the experimental observations.