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چکیده
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In this study, the effects of the core layering of sandwich structures, as well as arrange- ments of these layers on the ballistic resistance of the structures under high-velocity impact, were investigated. Sandwich structures consist of aluminum face-sheets (AL- 1050) and polyurethane foam core with different densities. Three sandwich structures with a single-layer core of different core densities and four sandwich structures with a four-layer core of different layers arrangements were constructed. Cylindrical steel projectiles with hemispherical nose, 8 mm diameter and 20 mm length were used. The projectile impact velocity range was chosen from 180 to 320 m/s. Considering constant mass and total thickness for the core, the results of the study showed that the core layering increases the ballistic limit velocity of the sandwich structures. The bal- listic limit velocity of the panels with a four-layer core of different arrangements, com- pared to the panel with the single-layer core, is higher from 5% to 8%. Also, for the single-layer core structure, by increasing the core density, the ballistic limit velocity was increased. Different failure mechanisms such as plugging, petaling and dishing occurred for the back face-sheet. The dishing area diameter of back face-sheets was proportional to the ballistic resistance of each sandwich structure.
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