This month’s Featured finite element analysis builds on our previous simulation of a free-air explosion inside a shipping container by including fluid-structure interaction (FSI). Using the explicit solver Radioss by Altair, the model captures the interaction between the structural response of the container and the surrounding air dynamics. The goal of this simulation is to showcase a method for modelling confined explosions with reflections using Radioss.
Methodology: Arbitrary Lagrangian Eulerian (ALE)
To accurately simulate both the structural components and the air, the ALE method is employed.
ALE is a numerical method which combines features of both these methods.
The shipping container is modelled using 3D shell and 1D beam Lagrangian elements. The container is made from Corten steel with an elastic-plastic material model which includes failure. The vertical motion of the container is constrained at the base.
The air and the TNT are modelled using 3D solid hexahedral Eulerian elements. The air dynamics are governed by the Ideal Gas Law. The explosion is simulated using the Jones-Wilkins-Lee (JWL) equation of state, which describes the detonation products of a solid explosion.
A Coupled Eulerian-Lagrangian (CEL) interface handles the interaction between the blast wave traveling through the air and the container structure. This is a penalty-based coupling method. This means that the fluid can penetrate the solid structure. Based on the penetration and stiffness of the interface, a force is applied to the solid structure. The mesh near the interface and the interface parameters both have a significant influence on the results.
Our featured video highlights the overpressure in the air and the blast pressure on the container, though the model also provides insights into stresses and deformations, among other parameters.
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