Dynamic response of functionally graded multi-layered plates to localised blasts

Functionally graded multi-layered metallic (FGMM) plates integrated with graduation of constituent, light-weight, high-strength and customised properties are highly desired as blast-resistant structures. Meanwhile, very limited investigation on their dynamic response to localised blast loading involving large deflection has been reported. Here, we develop an analytical model to investigate the large inelastic deformation response of FGMM plates under localised air blast loading. Nonlinear loading and constitutive characteristics, such as the localised variability and exponential decay shape from a close-in blast, as well as the effects of strain rate sensitivity and strain hardening, were considered. Extended Hamilton’s principle is applied to derive the governing equation of motion for FGMM plates. Blast tests were performed to validate the analytical predictions of the temporal evolution of transverse central deflection and permanent transverse deflection. The analytical model is used to discuss a number of issues relevant to the dynamic response of FGMM plate, including the effect of loading distribution, influence of different constitutive behaviours, energy partitioning, blast resistance and deformation mechanism. Results in this work show that FGMM plate has superior blast resistance (with 14.9% less permanent transverse deflection) to that of a monolithic steel plate with identical weight, which was attributed to the higher effective specific strength. Localised explosive action triggers a distinct initial bulging deformation phase, resulting in significant external work done. This study provides new insights into the dynamic response of the blast-loaded FGMM plates, while further highlighting their potential in the application of blast-resilient systems.