An Investigation into Plastic deformation of sandwich structures with aluminum facesheets and pumice core under low-velocity impact loading

In the current research study, the large plastic deformation and failure mechanism of sandwich structures with aluminum facesheets and pumice core under low-velocity impact loading have been investigated. The drop hammer testing machine was used to apply the impact load on the specimen at seven different energy levels 34.3, 68.6, 102.9, 137.2, 171.5, 205.8, and 223 J. To achieve the mentioned energy levels, the weight of the impactor was considered constant and equal to 3.5 kg and the standoff distance of the hammer was changed from 1 to 6.5 m. 16 experimental samples were considered in two types of layering with and without pumice core. Also, in this series of experiments, the thickness of facesheets was fixed and two different thicknesses of 16 and 32 mm were considered for the core. Experimental results showed that at all energy levels, the sandwich panel with 16 mm pumice core shows a smaller deformed area due to the shorter porous space between two facesheets. Also, at low energy levels, the thickness of the pumice core does not play a key role in improving the impact resistance of the structure. Compared to the coreless sandwich structure, the use of a very low-mass pumice core can prevent the plastic deformation of the rear facesheet, and the 16 mm thickness of the pumice core can even prevent the front surface from petalling.