Influence of epoxy adhesive layer on impact performance of TiB2-B4C composites armor backed by aluminum plate

Influence of adhesive layer, used to bond ceramic tiles and back plate, on high velocity impact performance of the ceramic/metal composite armor was studied by experimental and numerical investigations. Two types of targets, monolithic ceramic structures and laminated ceramic structures backed by aluminum alloy, with different thicknesses of adhesive layer (0.5 mm, 1.0 mm, 1.5 mm and 2.0 mm) were considered. Results indicated that the size of fractured ceramic was decreased with the increase of adhesive thicknesses. And the size of fragments in the laminated ceramic/aluminum structures with adhesives was smaller than that of in the monolithic ceramic/aluminum structures. A change in crack trajectory were observed at the ceramic/adhesive layer interface of the laminated ceramic composites armor. It showed that the capacity of energy absorption would be improved at the lateral direction, and the failure of the second ceramic plate would be delayed by the change. The penetration depth of the monolithic ceramic/aluminum structures bonded by epoxy resin was found to be greater than that of the armor without adhesive. But the addition of adhesive layer improved the impact performance for the laminated ceramic/aluminum structures. In addition, the depth of penetration was decreased with the increase of adhesive thicknesses for both forms of composite armor. Then simulation results showed that adhesive thickness has little effect on stress wave propagation of inner adhesive layer. Due to the difference of elastic impedance among target plates, the pressure amplitude in different plates was decreased by addition of the adhesive layers, especially for the laminated ceramic/aluminum structures. Lastly, the shear strain and shear strain rate of adhesive layer was decreased with the increase of adhesive thicknesses, which improved the impact performance of laminated composites armor.