Coupled Fluid-Structural Analysis of Explosion Containment Using Crushable Sandwich Structures

Abstract Recent improvements in cellular material technologies, such as foams and hierarchical structures, have made lightweight single-use containment structures an effective solution for neutralizing rogue explosives. While previous studies have focused on their response to open or partially confined explosions, this study investigates their dynamic response to completely confined internal explosions. Such explosion events are more challenging to simulate due to the nonlinear shock wave propagation, reflections, and interactions. In this work, we employ our three-stage, two-way coupled fluid-structure interaction simulation framework that captures detonation, shock propagation, and large, plastic structural deformations on their respective time scales. The framework uses a partitioned procedure to couple a nonlinear finite element structural dynamics solver with a high-resolution finite volume compressible multiphase fluid dynamics solver. The dynamic kinematic interface condition at the shared fluid-structure boundary is enforced using the embedded boundary method. Interfacial mass, momentum, and energy fluxes across the fluid-structure interface are computed by constructing and solving local one-dimensional fluid-structure Riemann problems featuring a constant structural wall velocity. A case study of a sandwich foam composite containment structure with steel skin layers and an aluminum foam core subjected to a 250 g TNT explosion is presented. The structure features the standard pressure vessel design with ellipsoidal end caps that are connected by a cylindrical section, assumed to be completely sealed. The metallic foam’s long plastic plateau and nonlinear densification properties are modeled using an extended von Mises yield criterion and a nonlinear hardening law, whose material parameters are a function of foam density. The results show that due to the effective energy absorption capabilities of metallic foams, the maximum effective plastic strain developed in the outer skin layer is 4%, well below its failure threshold. Moreover, a comparative analysis with a thin steel containment structure of identical weight demonstrates that the sandwich composite structure performs 9 times more plastic work while dissipating 8 times more total energy of the internal explosion.