Experimental investigation on the ballistic resistance of monolithic and multi-layered plates against hemispherical-nosed projectiles impact

In this paper, the ballistic behavior of single, double-, three-, four- and six-layered plates impacted by hemispherical-nosed projectiles were experimentally investigated. Ballistic limit velocity for each multi-layered target was obtained based on the investigation of the effect of the air gap between layers, the number, order and thickness of layers on the ballistic resistance. The results showed that the monolithic thin targets presented more effective than multi-layered targets when the dominant response of monolithic targets were dishing and bulging which involved bending and stretching, and the ballistic limit velocities of multi-layered plates increased with the increase of the number of layers, although the multi-layered targets were less effective than monolithic targets. However, the monolithic targets had lower ballistic resistance than multi-layered targets if the total thickness above a specific value, the dominant target response changed from shearing to bulging and dishing when using multi-layered targets instead of monolithic targets. Moreover, the air gap decreased the ballistic resistance of multi-layered targets, but the air gap size had slight influence on the ballistic resistance. The order of layers affected the ballistic resistance of multi-layered targets, the multi-layered targets of two equal thick plates had the highest ballistic resistance followed by multi-layered targets of a thicker front plate and a thinner back plate, multi-layered targets of a thinner front plate and a thicker back plate.

► Air gap between layers diminishes the ballistic resistance of layered plates.
► The different layering effect results from the transitions of failure models.
► The change in thickness leads to the transitions of main failure models.
► The layering order affects the ballistic resistance of layered plates.
► The number of layers affects the ballistic resistance of layered plates.