Cellular origami sandwich panel cores used for blast energy absorption

Abstract

The objective of this dissertation is to explore various types of sandwich panel cores used within structural walls, so as to create optimal blast-resistant structural envelopes in firework factories. This is done by comparing five distinct sandwich panel core types with constant geometrical constraints for each type – such as volume, width, and thickness. These panels include a square honeycomb core, y-core, z-core, and two origami-type cores made from a single-layer Miura Origami core and another from a double-layer Miura Origami core. Such core types are compared to verify the unique qualities of Origami cores in contrast to traditional sandwich panel cores. Structural blast walls must absorb significant, massive and rapid loading in order to remain contained, meaning that the structure making up such walls must offer both strength and ductility so as to minimise the blast’s penetration risk. The two identifiable characteristics, which determine such properties, include the overall displacement of the walls composed of sandwich panels and the core's deformability. The former refers to the ability of the wall to control excessive deflections, which would cause damage to the structural components, such as the foundations and connections with other walls. On the other hand, the latter refers to the ability of the core to absorb energy such that, by following the principle of energy conservation, little-to no-energy is left to be dissipated to the wall boundaries. This research study adopted a research methodology by means of using numerical analysis computational software based upon the Finite Element Method (FEM). A total of 105 FEM numerical models were analysed in order to study these different characteristics, where each core type was tested against varying explosive TNT levels and the elevation aspect ratio of the walls. The walls were assumed to be simply-supported at the bottom and side edges, and free at the top so as to model the lack of restraint offered by frangible roofs. The blast analysis results showed that the best sandwich panel cores for constructing firework factory walls are the doublelayer Origami core and z-core, since, while some core types may produce better flexural stiffness than Origami cores, they prove to be inadequate for energy absorption, and vice versa. Moreover, the square honeycomb core experienced low deflection and, hence, high flexural stiffness, but it was inefficient in energy absorption. On the other hand, the z-core portrayed better overall flexural stiffness. However, this core type showed slightly inferior energy dissipation compared to the Origami cores. Finally, some thoughts on possible future research work are also presented.