Research On Meso-structure And Anti-penetration Capability Of Aluminum Foam Sandwich

Defence capability of operational objectives, such as warships and armored vehicles, can be divided into active defense capability and passive defence capability and passive defence system is the last lifeline of operational objectives. With the development of modern technology and the requirements of modern battlefield, states are developing new guided weapons actively, which are of high accuracy and strong anti-reconnaissance capability.Improving the passive defence capability of operational objectives can reduce the damage after the objectives are attacked and it is one of the important means to improve the vitality of the operational objectives. So while developing the active defense capability, developing passive defense capability has a strong practical significance.Aluminum foam is a kind of new materials with both structural and functional properties and there are a large number of regular or irregular holes distributing in its metal matrix.Compared to continuous dielectric material, it has the characteristics of lightweight, high energy absorption and other excellent mechanical properties. However, due to the low strength of pure aluminum foam, other materials with high strength are often required to enhance its mechanical properties. Aluminum foam sandwich structure is composed of two layers of high strength and thin panel and aluminum foam core. Aluminum foam sandwich has both the advantages of lightweight and high energy absorption efficiency of the core and the advantages of high strength material panel. It has broad application prospects in vehicles,ships, aviation and aerospace and other fields.Aluminum foam sandwich panels are often subject to impact by different shapes of fragments or projectile when used as the protective material. Therefore, studying its anti-penetration capability is important. In this paper, meso-structure geometric structure of aluminum foam sandwich was modeled and its anti-penetration capability was studied by LS-DYNA. The following four points are the main contents and results:(1)The processes of blunt and conical projectiles penetrating thin metal target and aluminum foam sandwich panels were described. The ballistic limit velocities of blunt and conical projectiles penetrating metal thin target were deduced by the law of conservation of energy and the law of conservation of momentum. By using cavity-expansion theory and Newton law of motion, a multi-stage kinetic model of projectile penetrating aluminum foam sandwich was introduced.(2)Meso-structure geometric structure of open-cell aluminum foam was modeled and the process of its dynamic compression was studied. The method of modeling geometric structure of open-cell aluminum foam was proposed in this paper by infiltration casting method. Using SPH algorithm, geometric structure was modeled by the discrete element software PFC3 D and self-made pretreatment program. Its compression performances under quasi-static and dynamic conditions were studied by LS-DYNA. The results show that the simulation of meso-structure geometric structure of open-cell aluminum foam based on infiltration casting method can reflect the randomness of aluminum foam hole in spatial arrangements. The calculated platform stress is consistent with the theoretical calculation. Using SPH algorithm can reproduce the dynamic compression process and observe the deformation of inside cells.(3)Two different shapes of projectiles were used to penetrate the thin metal target and the aluminum foam sandwich and ballistic limit velocity, residual velocity and injury of targets were calculated. Meso-structure geometric structure of aluminum foam sandwich was modeled based on infiltration casting method and the geometric structure of blunt and conical projectiles were modeled by TrueGrid. The ballistic limit velocities and residual velocities of different shapes of projectiles penetrating thin metal target and aluminum foam sandwich were calculated and the results were compared with the theoretical analysis. The results show that the numerical simulations are coincident with the theoretical calculations. Aluminum foam layer can significantly improve the anti-penetration capability of targets. Compared with conical projectile, the anti-penetration capability of aluminum foam sandwich to resist blunt projectile is more significant.(4)The anti-penetration capability of aluminum foam sandwich was studied by threedimensions which were the comparation of aluminum foam sandwich and only mental panel,the comparation of blunt and conical projectile and the comparation of the components of aluminum foam sandwich. The results show that the energy absorption of aluminum foam sandwich is larger than only mental target. With the increase of initial velocity of projectile,the energy absorption of target also increased. The injury of targets caused by blunt and conical projectiles are different, which lead to the vary of energy absorption of different components of aluminum foam sandwich.