Model-based simulation of the synergistic effects of blast and fragmentation on a concrete wall using the MPM

Abstract

With the development of the material point method (MPM) that is an extension from computational fluid dynamics (CFD) to computational structural dynamics (CSD), a model-based simulation is performed in this paper to investigate the synergistic effects of blast and fragmentation on structural failure. As can be found from the open literature, the synergistic effects of blast and fragmentation have been usually simulated via a combined approach through an interface between CFD codes and CSD codes. As a consequence, numerical solutions are very sensitive to the choices of different time steps and spatial meshes for different physical phenomena, especially for the multi-physics involved in the initiation and evolution of structural failure. Hence, a coupled approach within a single computational domain seems to be necessary if objective results are needed. In this paper, a numerical procedure is proposed with the use of the MPM, so that different kinds of gradient and divergence operators could be discretized in a single computational domain without involving fixed mesh connectivity. To simulate the evolution of impact failure, the transition from continuous to discontinuous failure modes is identified via the bifurcation analysis. The potential of the proposed model-based simulation procedure is demonstrated through 1D and 2D isothermal cases including cased bomb expansion and fragmentation, blast wave expansion through a broken case, and blast and fragment impact on a concrete wall. The preliminary results obtained in this numerical study provide a better understanding of the synergistic effects on impact/blast-resistant structural design. An integrated experimental, analytical and computational effort is required to further improve the proposed procedure for general applications.