Protective performance of sacrificial cladding with foamed geopolymer core under impact loading

Abstract

In the present study, a novel sacrificial cladding with a foamed geopolymer (FG) energy-absorbing core was proposed for structural protection to resist impact loading. First, the mechanical and energy absorption performance of FG was investigated through quasi-static and dynamic compressive tests. The test results demonstrated that an increase in density or strain rate would significantly enhance the energy absorption capacity of FG. Based on the test results, a phenomenological constitutive model of FG, considering the effects of density and strain rate, was proposed. Subsequently, the drop hammer impact tests were conducted on the monolithic steel panel (MSP, regarded as the protected structure) and the cladding-structure system (CSS) to evaluate the protective performance of the proposed cladding. The impact test results indicated that MSP exhibited a significant local indentation in its central region, while the monolithic steel panel in CSS primarily demonstrated a global bending deformation. In addition, with the numerical model validated by the impact test results, the effects of the impact loading area, initial impact momentum, and the FG core density on the protective performance of the proposed cladding were further numerically investigated. The numerical results demonstrated that, although the monolithic steel panel in CSS exhibited a slightly larger residual deflection compared to MSP in some cases, the sacrificial cladding still provided effective protection in terms of damage extent, energy absorption, and load transfer, especially under small impact loading areas or low initial impact momentum. It was noted that, due to the premature densification or limited deformation of FG, the sacrificial cladding with either low- or high-density FG cores led to more impact energy and a higher peak load transferred to the protected structure, demonstrating unfavorable protective performance. The results in the present study provided valuable references for the design and application of sacrificial cladding with FG core.