The influence of core density on the blast resistance of foam-based sandwich structures

This paper investigates the influence of varying core density on the blast resistance of sandwich panels based on crosslinked PVC cores and aluminium alloy skins. Initially, the findings of a series of compression and single edge notch bend and shear tests are presented in order to characterise the strength and toughness characteristics of the foams and generate data for input into the finite element models. Experimental blast tests employing a ballistic pendulum are then reported, where it is shown that damage within the sandwich panels becomes more severe as the density of the foam core is increased. Indeed, panels based on the lowest density foam (60 kg/m3) did not exhibit any fracture or debonding over the range of impulses considered, instead absorbing energy through plastic deformation in the metal skins and compression of the foam core. In contrast, significant damage, in the form of Mode I core cracking and debonding at the skin–core interface, was apparent in the higher density core systems. A finite element analysis has been employed to model the blast response of the sandwich structures. The FE models successfully predicted the post-test deformed shapes of the panels. These analyses were also used to determine the individual contributions of the skin and core to the energy-absorbing capacity of the various sandwich structures. Here, it was shown that the foam core absorbs more than fifty percent of the overall energy dissipated during the test.