Study on the Penetration Characteristics of Water Entry Rod Projectile into Liquid Cabin at an Attack Angle

The penetration of a projectile into a warship broadside liquid cabin is usually a non-ideal penetration process. To explore the protective effects of the broadside liquid cabin of a large warship against the non-ideal penetration of rod projectiles and to provide reference for the design of new liquid cabin structures, ballistic impact tests of rod projectiles penetrating the liquid cabin at different attack angles were carried out. Combined with numerical calculation, the impact of the attack angle on the water entry and penetration characteristics of the projectile into the liquid cabin as well as their failure modes were studied. The overturning and yawing of the projectile in water were analyzed. The pressure load characteristics in the liquid cabin and the deformation/failure modes of the projectile and the liquid cabin were identified. The results showed that: multiple overturning and yawing occur in the projectile with an initial attack angle during penetration into liquid; the yaw direction is mainly affected by the initial attack angle and projectile attitude; the projectile mainly undergoes four basic failure modes, namely, asymmetric mushrooming at the projectile nose, side erosion, overall plastic bending and fracture; the actual failure of the projectile is a combination of the basic failure modes; the overall plastic bending and fracture are mainly related to the length to diameter ratio, initial attack angle and initial projectile velocity; the front plate of the liquid cabin may undergo tearing along the central plastic hinge line of the plate: at a small attack angle, the tear is “I” shaped, and at a large attack angle, it is “X”-shaped.