The MHICA project focuses on the experimental and numerical study of the performances of bilayer armour configurations under multi-hit loading of small- and medium-calibre bullets. Bilayer armours composed of a ceramic plate as front face associated with a ductile backing (made of metal or composite) are nowadays considered as the most performing systems against these threats. Indeed, thanks to their high hardness and compressive strength, ceramics materials favour projectile blunting and/or breakage, thereby limiting the penetration capacity of the bullet. However, few microseconds after impact, the shock wave propagating through the ceramic tile initiates the onset and the growth of numerous oriented microcracks. Thus, most of the dynamic interaction of this type of ballistic event comes down to the penetration of a damaged or broken projectile into an intensively fragmented target. The mechanical behaviour of the fragmented ceramic is supposed to play a major role in the penetration process as well as in case of multiple impacts. This aspect of the behaviour remains largely unexplored and one cannot find in the literature a robust modelling approach based on reliable experimental data. To date, numerical tools are still underutilized in the design process of ceramic-based protective systems. Indeed, it rather relies on empirical approaches with series of ballistic tests. However, considering the numerous parameters to take into account (projectile characteristics, impact velocity, angle of incidence, thickness of constitutive parts …), numerical simulation represents a promising way to optimize the protective systems. Nevertheless, to be predictive, the models implemented in finite element codes have to be reliable, robust and validated by using accurate experimental data. The MHICA project proposes: - to perform instrumented ballistic tests against bilayer armour configurations made with dense or porous silicon carbide front plate, - to study the damage induced in impacted bilayer armour configurations by using CT-tomography analysis, - to develop a new experimental method to characterize the behaviour of fragmented ceramics and to identify a constitutive model to be implemented in a finite element code, - to numerically simulate a single-impact of AP projectiles with both finite-element method and discrete element method, - to numerically simulate a multiple-impact of AP projectiles with the discrete element method taking into account for the initial cracking state provided by the tomographic analysis, - to compare the computational results with the experimental data. Finally the present work should make possible to better understand the relationship between ceramic's microstructure and their dynamic fragmentation on the one hand, and the impact behaviour of the fragmented ceramic one the other hand. The global approach proposed herein, composed of experimental characterization, modelling and numerical simulations, constitutes an innovative way to improve the understanding of the links between material characteristics, mechanisms activated at high strain-rates and performance of an armour system. The works carried out in this project will benefit to the DGA by providing tools to optimize the protective solutions such as body armour of the foot soldiers or the police task forces as well as armour configurations used in vehicles operating on the battlefield