Perforation of sandwich plates with graded hollow sphere cores under impact loading

Abstract

In this paper, sandwich plates made from 0.8mm 2024 T3 aluminium alloy skin sheets and graded polymeric hollow sphere cores (having various density gradients) are studied. The experiments at 45m/s were performed with an inversed perforation setup using SHPB system. Quasi-static tests using the same clamping system allow for the rate effect investigation. Numerical simulations are performed in order to get the indispensable local information (which is not experimentally available) to better understand the perforation process. With these experimental and numerical tools, it is found that the gradient profiles change the perforation process under studied impact loading, whereas they have no influence under quasi-static loading. Under impact loading, a competition of two deforming scenarios at the early stage governed the whole process afterwards. One is the global crush of the first layer in contact with the incident skin and the other is the piercing of the incident skin sheet. When the first layer is rather strong, the incident skin sheet breaks and the perforator makes a hole in the core afterwards. When the first layer is rather weak, the skin sheet folds into the core and develops a much more energy consuming process. The best gradient profile in terms of the energy absorption capacity as well as the non-sheet breaking criterion should be a lower first layer and a progressively enhanced core.

Relation of impact strength to the microstructure of functionally graded porous structures of acrylonitrile butadiene styrene (ABS) foamed by thermally activated microspheres

“…One important result from their work suggested placing the high density foam core against the top surface skin for an improved perforation resistance. Zeng and coauthors [17] developed sandwich plates with face sheets made of aluminum alloy while the cores were made of graded polymeric hollow sphere composite with various density gradients. The authors concluded that the best gradient profile in terms of the energy absorption and the non-sheet breaking criterion should be a weaker first layer and a progressively enhanced core.…”

“…17 shows the thermal gradient versus diameter difference between T L and T H sides for 10% microspheres loading and different T L values. The trend of increasing diameter difference with increasing thermal gradient was observed at T L of 160 C for all T H values.…”

A Collision Model for Protective Structure with Gradient Metallic Cellular Material under Low Velocity Impact

“…Because of the outstanding properties, such as the low weight and high efficient energy absorption [1,2], the metallic cellular materials have been extensively applied in the civilian and aerospace fields (e.g., reentry capsule and airdrop platform) for impact mitigation applications. Among the metallic cellular materials, the gradient metallic cellular material has attracted many research interests [3,4].…”

Energy absorption of graded foam subjected to blast: A theoretical approach

“…The relatively stiffer outer part of smaller cell size provides higher resistance to external loads such as bending and buckling while the less dense inner part of larger cell size reduces its total weight. Recently, a few studies on graded cellular solids have been carried out, showing that they may have some merits when employed appropriately [20][21][22][23][24][25][26]. However, the underlying mechanism of high velocity crushing remains not reasonably understood.…”