Research On Damage Equivalence Of Multi-layer Target Of Ship Combining Projectile And Target

When studying the penetration capability of anti-ship projectile to ships,ship targets are usually designed and penetration tests are carried out.The penetration test can predict the penetration position of projectile,the trajectory and deflection characteristics of projectile,and it is also the basis for further chamber explosion test.However.at present,there is no mature technical means for the boundary conditions and material equivalence of ship target.Aiming at the penetration of anti-ship projectile into large and medium-sized ship targets,this paper studies the equivalent conditions of target damage and proposes the equivalent methods of target boundary conditions and material.The ship slab is simplified as an elastic foundation beam.Based on Timoshenko beam theory,the dispersion relation and critical frequency are solved.The dispersion similarity rule of target structure 1s obtained.The criterion for selecting the size of target slab which meets the dispersion equivalence is proposed.The requirement of the minimum edge length of target slab is obtained,and the design method of the minimum boundary size which makes the penetration process not affected by the reflection of the boundary stress wave of target slab is proposed.Through numerical calculation,it is found that the target breaks can be divided into four types,and the relationship between the four types of breaks and angle of attack and angle of attack is summarized.Fitting formulas of target breaks and various influencing parameters are obtained.Based on the formulas,the equivalent method of target material is established.According to this method,the equivalent design of target plates with different materials is carried out and the numerical calculation is carried out.Based on the assumption of adiabatic shear plugging failure,the formula of residual velocity of projectile penetrating stiffened plate is derived.Based on this formula,an equivalent design method of target material for residual velocity is proposed,and the method is verified by numerical calculation.According to target damage characteristics and boundary equivalence nethod,a preliminary design scheme of ship target is proposed.The rocket sled test of the above ship targets is earried out.The test data are recorded and analyzed by high-speed photography.The error between the test data and the numerical results is about 10%.Comparing the different methods of material equivalent design of ship target system,including stiffness equivalent,bending strength equivalent and target damage and ballistic characteristics equivalent,the numerical calculation of the equivalent ship target designed according to the above equivalent principle is carried out respectively.It is found that the strength of ship target system based on stiffness equivalent is weaker,and that of ship target system based on bending strength equivalent is stronger.The strength of the ship target system based on the equivalent damage and ballistic characteristics of the target plate is equivalent to that of the original target system.