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

在穿甲弹撞击双层陶瓷/背衬保护系统的过程中，会产生动态拉伸应力，从而导致大量定向裂纹的产生和传播。这种强烈的拉伸损伤（称为碎片）会影响屏蔽层的性能及其抵抗多重冲击的能力。与未破坏的抗压强度相比，碎裂陶瓷的残余约束强度相对较弱，但不可忽略。因此，对预碎陶瓷的动态特性进行表征对于设计改进的装甲解决方案非常重要。在这项工作中，一种称为串联测试的冲击构型被应用到两种具有不同微结构的氧化铝陶瓷上，该构型包括正常冲击和穿透冲击。与称为“ MAINa”（一种珍珠质的氧化铝）的生物启发的砖瓦陶瓷相比，传统的98％纯氧化铝具有更高的抗弯强度和断裂韧性。在进行正常的冲击试验后，通过X射线计算机断层扫描分布对碎片尺寸进行分析，结果表明，珍珠母状氧化铝中的平均碎片尺寸明显更大，从而证明了碎片尺寸与碎氧化铝陶瓷的耐穿透性。最后，基于反向方法确定了两种氧化铝陶瓷在破碎状态下的强度，在反向方法中考虑了Drucker-Prager模型对渗透测试进行了数值模拟。