Mechanism And Performance Research On Penetration Resistance Of Novel Protective Liquid Cabin

With the rapid development of anti-ship missiles,them have the outstanding abilities in concealment,hitting precision and tremendous power,which have become the major threaten of the large surface vessels.The large number of high-velocity fragments caused by explosion warheads of missiles could cause serious damage to important equipments and personnel on the vessel,leading to the incapacity or even sink of ships.Therefore,a large surface vessel was equipped with the passive protective structures as the last defense line to protect the equipment and personnel from dangerous explosive load.Generally,the passive protective structure of the vessels usually possess the multilayer cabins,which could defend against the blast loadings from the anti-ship missile.The liquid cabin plays very important role in the multilayer protective structure,which has prominent capacity in attenuating the high velocity fragments.There are two basic problems existed in the process of liquid cabin penetrated by the high-velocity fragments,including the protective mechanism of liquid cabin and the techniques for reducing the damage of the liquid cabin.By combining the new materials and structures,the experimental,analytical and numerical methods are also used to analyze the defense mechanism and the optimization design method of liquid cabin against high-velocity fragments.The results could be the guidance to the design of liquid cabin and other similar multi-layer protective structures on warships.The detailed research work of the paper are as follows:(1)A series of experimental tests of liquid cabin penetrated by a highvelocity projectile was performed.During the tests,high-speed camera was employed to capture the evolution process of cavity in liquid cabin.Based on energy conservation theory,the simplified analytical model for predicting the residual velocity of projectile was derived by combining the motion equation and the energy dissipation characteristics of projectiles traveling through the fluid.In addition,the proposed analytical model further considered the influence of water in front of the target.The effect of both the deflection of back target in liquid cabin and the increased diameter of projectiles have been taken into consideration as well.The calculated results of the analytical model are in good agreement with the experimental data.(2)The commercial finite-element code AUTODYN was used to simulate the physical process of the high velocity fragment impacting the liquid cabin.After verifying the accuracy of the numerical smethod,a serial analysis was carried out,in which the influence of the width of the liquid cabin,the initial velocity,the incident angle of the fragment and the thickness of target plate on the damage of the structure was analyzed.The results of the analysis are helpful to understand the damage and response characteristics of liquid cabin and similar structures.(3)The contermeasure of adding the ceramic material layer to the front wall of liquid cabin was proposed to resist the penetration of high-speed projectile.Serial studies of anti-penetration capacity of ceramic/metal composite protective structures have been conducted.Based on the modified Florence’s model,the velocity attenuation formula of the projectile which penetrate the ceramic/liquid cabin was deduced.The penetration process of the projectile through ceramic/metal composite target was simulated with AUTODYN to validate the reliability of theoretical model.(4)Research the protective performance of shear thickening liquid.The viscosity of STF in different shear rates and the dynamic response characteristics of STF in different strain rates were studied respectively.A user subroutine which contains the viscosity property of STF was developed based on commercial finite-element code ABAQUS.The numerical results show a good agreement with the experimental results,by which the accuracy of the user subroutine is verified.The influence of fluid density and initial velocity of projectiles on velocity attenuation were also analyzed numerically.Finally,the ballistic performance of water/STF composite fluid liquid cabin was studied.Based on the numerical method,the drag coefficient formula of the projectile traveling through STF was deduced.The simplified analytical model for predicting the residual velocity of projectile was derived by the drag coefficient formula.