Dynamic compaction of foam under blast loading considering fluid-structure interaction effects

Abstract

A numerical approach for one-dimensional dynamic compaction of foam produced by a blast pressure wave is presented. Approximate numerical procedures for solving the Riemann problem associated with shock are implemented within the Godunov finite volume scheme for the fluid domain. A numerical framework for enforcing the traction and velocity continuity across the fluid–solid interface is presented. Numerical evaluation is performed considering foams of different strengths. Results of the analysis indicate that the fluid-structure interaction effects are significant only in the early part of the blast pressure history. The energy consumed during the dynamic compaction of foam produced by a blast pressure wave is higher than the energy obtained as the area under the quasi-static stress-strain curve of the material. During the dynamic compaction of foam, there is a difference between the energy absorbed by the foam and the total energy consumed in the compaction of foam, which is available as kinetic energy of the compacted foam. The compaction of the porous material continues even after the blast over-pressure decreases below the crushing strength of the foam because of the kinetic energy available in the compacted foam. The energy transferred from the blast pressure wave to weaker foam is higher than the energy transferred to foam with higher crushing strength. There is a critical length of the foam when the energy absorbed by the foam is totally dissipated by the compaction of the material and the kinetic energy in the compacted foam becomes equal to zero. When the length of foam is greater than the critical length, the impulse of the transmitted pressure pulse is equal to the impulse of the reflected blast over-pressure. There is however a decrease in the pressure amplitude which depends upon the crushing strength of the foam.