Numerical Investigation On Penetrating Grillage Structure Of Large Naval Ship Side Shell

Side shell plays an important role in vitality of large naval ship, it is used as a barrier to defense the anti-ship missile. Grillage structure of side shell as the first protective structure that it plays an important role in limiting further deep of Semi-Armor-Piercing warhead. In order to ensure the other performances of the large naval ship, the ship cann't equip thick amored as land tank. In order to decrease the residual velocity of projectile to the maximum extent when side shell grillage structure of large naval ship keep mass certain, arranging reasonably mass of plate and beam and distance of beam is a good protective mode. Therefore, it is of great significance that researching on penetrating grillage structure.This paper carried firstly out numerical investigation on penetrating thin plate and simulated the penetrating process with AUTODYN is verified by comparing research on between result of mumerical calculation and experimental. Then it simulated penetrating thin plate by truncated cylindroconical projectile with different incidence angles and initial velocities. The failure modes of thin plate impacted by truncated cylindroconical projectile with different incidence angles were studied. Energy absorption of target and residual velocity of projectile were also studied. A failure mode of pyriform hole and the concepts of slip and spring back were put forward. Residual velocity cruve of projectile with different incidence angles and initial velocities was fitted. And ballistic limit velocity and residual velocity formulation was deduced. The residual velocity of projectile was nearly equal between vertical penetrating and oblique penetrating.A oblique penetrating petalled mode was developed based on the failure process and failure mechanism of the truncated cylindroconical projectile oblique penetrating. Energy consume, ballistic limit velocity and residual velocity formulation was deduced based on the conservation of energy principle. The result of formulation was fit well with FEM analysis by comparative analysis of the residual velocity with different angle of incidence and initial velocity. According to the side shell grillage structure of large naval ship and basic parameters of existing advanced anti-ship missile warhead, projectile model and 32 types of grillage structure with different thinkness and reinforced were designed. Aiming at four typical impact positions carried out numerical simulation of penetrating process, the results show that stiffeners enhance the rigidity of target, and change the whole structure capability and the failure pattern of target. Numerical investigation showed that energy absorption by grillage structure is influenced by size of transverse stiffened, size of longitudinal stiffened and distance of longitudinal with different impact positions. Energy absorption by grillage structure is influenced by size of transverse stiffened only when projectile impacted at crossover of transverse stiffened and longitudinal stiffened and only at transverse stiffened. And this effect enhance with the plate thinkness reduce. In a word, energy absorption by grillage structure has little effect when change size and distance of longitudinal. For the same mass, different sizes and different layouts of longitudinal stiffened grillage structure, energy absorption by grillage structure of lager size and lager distance of longitudinal stiffened is better than small size and small distance of longitudinal stiffened when longitudinal stiffened keep mass certain, and projectile impact at crossover of transverse stiffened and longitudinal stiffened and only at longitudinal stiffened. Energy absorption by grillage structure with equal mass and different arrangements have little effect when projectile impact only at transverse stiffened. Energy absorption is better with the plate thinkness increase. When plate thinkness of grillage structure increase to a certain exent, energy absorption by grillage structure is enhance less with further increase of plate thinkness. Initial velocity and terminal velocity of projectile showed approximate linear relationship wherever impact position is. And terminal velocity of projectile have no significant distinction.