Experimental investigation of polyurea coated aluminum plates under strong hydrodynamic shocks

Abstract

Polyurea has been used in armor applications for over a decade. Its ability to mitigate shock waves and survive after experiencing large deformations makes it suitable for structural protection purposes. One of the many uses of polyurea coatings is in maritime structures, in which polyurea is not only a mechanical armor but can also serve as chemical protector against corrosion due to its high resistance to environmentally aggressive conditions. To further implement such applications, one must understand the effect of polyurea coatings on the overall structural response to hydrodynamic shocks. An experimental investigation of high-pressure shock-loaded polyurea coated aluminum plates is presented. These experiments add to previous experiments that are described in detail in Rijensky and Rittel (2016) [1]. The present experiments reveal the effects of polyurea coating on the fluid structure interaction taking place between shocked water and aluminum plates. This interaction can be the result of numerous scenarios ranging from violent blasts in water to relatively milder loads like wave slamming. Emphasis is put on the selection of the coated side of the aluminum plate, considering those different interactions and their influence on the structure. The presented setup is also an interesting experimental physics case study as the deformation under shock process involves soft materials, fluid-structure interaction and conventional engineering materials deforming all together and affecting one another. Whereas weak shock mitigation was found to favor polyurea on the wet side of the plate, the present work reveals that for strong shocks, polyurea must now be applied on the dry side, thereby revealing a dependence of the optimal placement of the protective layer on the shock intensity.