Experimental study on the anti-penetration characteristics of liquid-filled structure with air layer

The study aims to explore the damage characteristics and protection technologies of liquid-filled structures under high-speed projectile impact. A series of penetration impact experiments were conducted by focusing on different air layer configurations. By using high-speed camera and dynamic measurement systems, the effects of air layers on the projectile penetration, pressure wave propagation, cavitation evolution, and structural dynamic responses were analyzed. The results showed that the rarefaction wave reflected from the air-liquid interface significantly reduced the peak and specific impulse of the initial pressure wave, thereby diminishing the impact load on the structure. Additionally, the compressibility of air layers also attenuated the cavitation extrusion load. Both front and rear plates exhibited superimposed deformation modes, i.e., local deformation or petal fracture with global deformation. Air layers effectively mitigated global deformation. However, when the air layer was positioned on the projectile's trajectory, it split the water-entry process and velocity attenuation of the projectile into two relatively independent phases. And the secondary water entry pressure wave caused more severe local deformation and petal fractures on the rear plate. • The influence of the pre-set air layers in the liquid-filled structures on the peak and duration of pressure wave is revealed. • The deformation modes of the front and rear plates are divided into global deformation and local deformation. • An air layer along the penetration trajectory generates secondary pressure wave during projectile secondary water entry, exacerbating local damage to the rear plate. • The pre-set air layers can notably mitigate the global deformation of the front and rear plates.