Large inelastic response of polyurea-coated steel plates to confined blast loading

The large inelastic deformation performance of monolithic steel and polyurea–steel laminate plates to confined blast loading is investigated through a combination of experiments and finite-element modelling. Emphasis is placed on elucidating how the location of the polyurea coating(s) and steel substrate, relative to the direction of loading, affects their inelastic deformation and the impulse and energy transfer to the laminate plates. Experimental results show that monolithic steel plate outperforms – using the maximum central deflection as a criterion – its equivalent polyurea–steel laminate of equal mass in confined blasts. Results from finite element simulations, which will be shown to be in good agreement with the experiments, will reveal that a longer response time for the polyurea–steel laminate attributes to the greater saturation impulse and, in turn, the increased deformation over its monolithic counterpart of equal mass. The internal energy of a laminate plate, unlike its monolithic equivalent, is found to increase even after reaching its maximum central displacement through further out-of-plane deformation that spreads out laterally. The impedance mismatch between the elastomer and steel will be shown to play a key role in the amplification, or attenuation, of the blast wave depending on the placement of the elastomer. A parametric study is performed to elucidate the influence of thickness ratio and mass per unit area on the blast performance of the laminate plates.