Numerical modeling of brittle mineral foam in a sacrificial cladding under blast loading

Abstract

Cellular materials, such as aluminum foams, have proven to be excellent energy absorbents. They can be used as crushable core in sacrificial cladding (SC) for blast load mitigation. In this study, the blast absorption capacity of a brittle mineral foam-based SC is investigated through finite element modeling using the LS-DYNA software. The experimental set-up used consists of a rigid steel frame with a square cavity of 300 mm x 300 mm in the center The structure to be protected is simulated by a thin aluminum plate clamped into the rigid steel frame. The blast load is generated by 20 g of C4 high explosive set at a distance of 250 mm from the center of the plate. The blast absorption capacity of the considered SC is evaluated by comparing the maximum out-of-plane displacement of the center of the plate with and without the protective brittle mineral foam. The presence of the brittle mineral foam reduces the maximum out-of-plane displacement of the center of the plate at least by a factor of two. The brittle mineral foam is modeled both in solid elements and smoothed-particle hydrodynamics (SPH) by using Fu Chang's constitutive material law based exclusively on the results of quasi-static compression tests of the foam and a phenomenological relationship between stress, strain and strain rate. The SPH model predicts the maximum out-of-plane displacement of the center of the aluminum plate with an average relative error of 5% with respect to the experimental values.