The fluid-structure interaction between an aluminum plate and blast waves originating from an in-air explosion were investigated through numerical simulations. The plate liquid system consists of three domains: (i) ambient air for explosion and propagation of shock waves, (ii) the thin plate solid domain and (iii) fluid domain (air) in a confined space.

The explosion and propagation of shock waves were primarily solved in 1D using ALE1D approach in LS-Dyna explicit solver and then remapped to 3D for the sake of computational efficiency and time-saving. The 1D model is based on the balloon approach, which considers the explosive mixture to be confined in the soap film of a certain radius. The explosive mixture and ambient air were modeled using Linear Polynomial Equation of state with corresponding initial specific energies. This 1D model calculates for initial detonation and shock wave propagation till the time at which the waves arrive at the vicinity of plate yet no reflection occurs.

The 3D numerical model was initialized at the end time of 1D calculation i.e. at the time of arrival. In order to facilitate the constrained movement of the plate in response to blast waves, the mesh was considered to be deformable. The interaction between waves and plate was executed constrained Lagrangian approach, the explosive mixture, and ambient air was considered as a multi-material ALE group using the second order van-Leer advection algorithm. The aluminum plate was meshed using shell elements, whereas the fluid domain was meshed using solid elements. 

Numerical strain signals were extracted at certain intervals above and below the plate for structural analysis. The numerical model presented here was capable of capturing the complex phenomenon of blast wave reflections, the formation of tripe point and Mach stem. Moreover, it also captures the acoustic radiations from the plate before the shock front and also beneath the plate. The strain signals on the plate showed a non-linear evolution, depending on the position of the numerical gauge, therefore indicating the presence of membrane stresses.

These numerical simulations were validated through reduced scale experiments using gaseous detonations. The experimental data confirmed that the numerical model presented here is appropriate since they have also provided evidence of regular reflections and Mach stem.