Characteristics of combined blast and fragments loading

In this paper, the combined loading caused by blast and fragmentation impact has been studied. While there are methods for predicting the reflected blast wave pressure and impulse time history, the multi-fragment impulse has been rarely studied, and in fact, it is frequently neglected. This study deals with several aspects regarding the combined loading of blast and fragmentation impact and presents a simplified approach to assess the multiple fragment impulse in a way that would enable evaluation of its significance, relative to that of the blast. Results of the simplified approach were validated by their comparison with experimental data. Additionally, results for two different charges at various standoff distances were compared with those of numerical simulations, which had been previously validated. While the simplified approach provides estimates of the fragment impulse, it does not provide their detailed pressure-time history, which requires knowledge of the fragment shapes and penetration depths. Hence, the pressure time history was evaluated for three fragment shapes that represent upper and lower bounds for the peak pressure, as well as an intermediate case. The proposed approach indicates that there are cases where the fragment impact should not be ignored in the design of a protective barrier.