Numerical Simulation Of Structural Optimization Of Al-Ti Laminate Material And Anti-penetration Effect

In recent years,the research of Ti/Al₃Ti laminate composite has gradually become a hot spot.Because of its advantages of low density,high modulus and high specific strength,Ti/Al₃Ti laminate composite is widely used in the field of armor protection.Therefore,it is necessary to optimize the structure of Ti/Al₃Ti laminate composite,In order to obtain the laminate material with better ballistic performance.Firstly,LS-DYNA software is used to verify the finite element model of the bullet penetrating into the target plate,and the comparison is made from the penetration depth of the bullet and the failure and deformation of the target plate.It is found that the simulation results are in good agreement with the experimental results in the literature.On this basis,the volume fraction of Ti,the thickness gradient and the number of layers in the Ti/Al₃Ti composite were adjusted.It was found that the anti-penetration performance of the composite was the best when the volume fraction of Ti was 27.7%.When the volume fraction of Ti remains optimal,the anti-penetration performance of the material increases with the increase of the thickness gradient and the number of layers.It is found that the failure modes of the laminate material are different when the bullets with different shapes penetrate the laminate material.When the flat nosed bullets penetrate the target plate,the failure modes of the target plate are mainly shear plug failure,and the failure modes of the pointed oval bullets are mainly ductile reaming failure,The failure mode of hemispherical warhead to target plate is the combination of shear plug failure and ductile reaming failure.Among the three kinds of bullets,the penetration ability of the pointed oval bullet is the strongest,and the penetration ability of the flat headed bullet and the hemispherical bullet is almost the same.Then,based on the ballistic limit velocity theory,the effect of the back plate on the anti-penetration performance was analyzed.The effects of thickness ratio,backing material(Q235,2024 aluminum alloy,AZ31 magnesium alloy)and backing surface density on the ballistic performance of composite target were studied.The results show that the thickness ratio has a certain effect on the anti-penetration performance,and the anti-penetration performance is better when the thickness ratio of Ti/Al₃Ti laminate composite to Q235 steel back plate is 2:1.When the area density remains the same,the anti-penetration performance of composite target composed of Ti/Al₃Ti laminate composite and AZ31 magnesium alloy is higher than that of composite target composed of Q235 steel and 2024 aluminum alloy.With the increase of the area density of the back plate,the increasing trend of the ballistic limit velocity of the composite target gradually slows down,that is,the improving efficiency of the anti-penetration performance decreases slowly with the increase of the area density of the back plate.When the initial velocity of the bullet exceeds the ballistic limit velocity,the residual velocity of the bullet approaches gradually with the decrease of the area density of the back plate,which indicates that when the area density is less than a certain value,the change of the back plate material has little effect on the anti-penetration performance of the composite target.