Investigation of the multiple-fragmentation process and post-fragmentation behaviour of dense and nacre-like alumina ceramics by means of tandem impact experiments and tomographic analysis

During the impact by an armour-piercing projectile against a bilayer ceramic/backing protective system, dynamic tensile stresses are generated leading to inception and propagation of numerous oriented cracks. This intense damage, called fragmentation, affects performances shielding its capacity resist multiple impact. The residual confined strength fragmented ceramic is relatively weak compared undamaged compressive strength, however not negligible. Characterising behaviour pre-fragmented then interest design improved armour solutions. In this work, configuration tandem test, which consists in normal followed penetrating impact, applied two alumina ceramics with different microstructures: conventional 98% pure bioinspired brick-and-mortar “MAINa” (a nacre-like alumina) exhibits higher flexural fracture-toughness. Following tests, fragments size analysis conducted means X-ray micro-computed tomography distribution, reveals that mean significantly larger alumina, thus demonstrating correlation between resistance ceramic. Finally, both their state identified based on inverse approach tests numerically simulated considering Drucker-Prager model.