Research On Damage Failure Of Liquid-filled Structure Under Projectile Penetration Based On Material Point Method

In the field of aviation and military,the hydrodynamic ram caused by projectile penetrating the fuel tank is an important cause of aircraft crashes.The hydrodynamic ram is the process that the energy-containing liquid hits the wall and leads to the deformation of the structure when a high-speed projectile penetrates the liquid-filled structure and continuously transmits the energy to the liquid.Due to the particularity of hydrodynamic ram,the research on the damage failure of the liquid-filled structure under the projectile penetration is significant.Projectile penetration to the liquid-filled structure involves large deformation of materials,and grid distortion is easy to occur when the traditional finite element method was used to compute such problem.Therefore,the material point method was used in this paper to carry out numerical simulation of the damage failure process of various types of liquid-filled structures under the projectile’s penetration.The theory of the material point method for projectile penetration to the liquid-filled structures was introduced,which including the motion and deformation process of objects,governing equations,particle discrete equations and contact algorithms.The program of the material point method was written based on the theories,and the numerical simulation of the process that 600m/s and 900m/s projectiles penetrating aluminum fuel tanks with different liquid filling rates was carried out.The process of cavity formation,the residual velocity of the projectile and the peak pressure at the measuring point from numerical simulation were in good agreement with the experimental results in the literature.The feasibility of the MPM procedure in simulating projectile’s penetration to liquid-filled structures was verified.The influence of the projectile numbers and the distance on the damage failure of no-partition liquid-filled structures was studied based on the material point method.The results showed that the more the number of projectiles was,the more energy the liquid absorbed,and the more serious deformation the entry and exit wall of the liquid-filled structure was.The larger the projectile incident distance was,the weaker the superposition effect of the pressure shock wave in the liquid,the smaller the force of the energetic liquid on the structure wall,and the lighter the damage to the liquid-filled structure.The hydrodynamic ram of projectile penetrating various liquid-filled structures(double-layer partitions,lattice sandwich panel and grids)was simulated based on the material point method,and the influence mechanism of different parameters on the damage failure of liquid-filled structures was discussed.In the double-layer plate liquid-filled structure,the influence of different layer spacing on the rear tank was greater than that in the front tank.The liquid pressure peak of the front tank remained unchanged under different spacing,but the liquid pressure peak value of the rear tank showed a trend of first decreasing and then increasing with the increase of the spacing.The closer the position of the double-layer partition was to the exit wall,the weaker the superposition effect between reflected shock wave and incident shock wave,and the lighter the deformation of the entry and exit wall and the internal partition.In the lattice sandwich panel liquid-filled structure,the more the number of sandwich panels,the stronger the structure’s hindering effect on the shock wave transmission,the more energy the liquid and the sandwich panels absorbed,and the more serious deformation of the liquid-filled structure was.In the grid liquid-filled structure,as the number of grids increases,the shock wave transmission was more difficult,the pressure on the liquid near the ballistics was greater,and the damage of the liquid-filled structure was more serious.The shock wave transmission inside the structure was weaker and the overall force of the structure was more uniform with thinner grid thickness.The damage failure of no-partition liquid-filled structure,air-contain liquid-filled structure and grid liquid-filled structure under the specific research conditions of this paper by one projectile penetration were compared.The 3×3 grid liquid-filled structure with a wall thickness of 0.5mm had the least damage failure and the best penetration resistance under projectile penetrationThis paper provides a novel method for the study of projectile penetration into liquid-filled structures,and provides a reference for the follow-up protection research of liquid-filled structures.