Research On The Ballistic Performance Of Titanium Alloy And Ceramic Composite Armor

In this paper,the static/dynamic mechanical properties,material constitutive and ballistic effect of titanium alloy;the effects of different chip-off plates on the ceramic-cone and ballistic performance of ceramic composite armor;the optimization design method of composite armor and the effect of interlayer on ballistic performance were studied by using universal testing machine,split hopkinson bar device,ballistic experiment and numerical simulation.The specific research contents and research results are as follows:(1)The static/dynamic mechanical properties,dynamic constitutive model and the ballistic effect of titanium alloy were investigated.The test results have been showed as follows:TC4 titanium alloy had a significant strain rate effect.Compared to the static curve,the constitutive curve of dynamic tension and compression moved upper.With the increase of temperature,the hardening modulus of TC4 titanium alloy decreases linearly.With the increase of strain rate,the strain hardening modulus of TC4 decreased.The measured dynamic constitutive curve was used to get the Johnson-Cook model for annealed hot-rolled TC4 titanium alloy.For 12.7mm armor-piercing incendiary(API),ballistic limit thickness of TC4 plates was about 38mm.TC4 plates had positive effect when the thickness was in the range of 10mm to 30mm.The obliquity effect of TC4 plates for 12.7mm API was positive.The ricochet of TC4 plates with the thickness of 25.5mm was 62°.The obliquity of titanium alloy as base armor should be greater than 30°.Compared to the same areal density of TC4 plate,the appropriate chip-off plate could effectively reduce back spalling.In the design of titanium alloy/chip-off plate structure,chip-off plate which has lower acoustic reluctance than TC4 plate,high strength and toughness,such as aluminum alloy,should be choosed.(2)The effects of different chip-off plates on the ceramic-cone and ballistic performance of ceramic composite armor were investigated.The test results have been showed as follows:With the increase of acoustic reluctance of chip-off plate,ceramic cone showed an increasing trend.The ceramic cone of metal chip-off plate structure was greater,which could increase the acting area and improve the energy absorption of chip-off plate.The metal chip-off plates were conducive to the ballistic performance of ceramic.Based on the research of ceramic cone,the dynamic response model of chip-off plate and the expression of penetrating limit velocity were established.At the same thickness of ceramic and areal density condition,the order of protective performance from high to low was TC4 structure、7A52 structure、armor steel structure、aramid structure and glass fibre structure.Titanium alloy as chip-off plate had obvious advantages.(3)The optimization design method of composite armor was investigated.The results have been showed as follows:The design flow of double layer composite armor was established by substituting the ceramic cone parameter into the Florence model.Optimal design and calculation of different composite structure for Al2O3,SiC as bearer plate and 7A52,685,TC4 as chip-off plate were carried on.The minimum areal density and the minimum overall thickness curve were obtained at given speed condition.Then the ballistic experiments were designed to verify the calculation results.The theoretical calculation was consistent with the ballistic results.For the real sevice environment of ceramic composite armor,the optimization design method including the protection capability of base armor was established,which was verified by experiment.Calculation results were consistent with experimental results.Titanium alloy was a good choice for chip-off palte,which could not only improve the ballistic performance but also reduce the weight of composite armor.(4)The interlayer effects of ceramic/TC4 composite armor on stress wave propagation and ballistic performance were investigated.The results have been showed as follows:The nonmetal interlayer,especially glass fiber interlayer could greatly attenuate stress wave.The energy absorbed by projectile of metal interlayer structure was less than that of nonmetal structure.The maximum stress transmitted to chip-off plate of non-metal structure was significantly smaller than that of metal interlayer structure.With the decrease of the impedance of the interlayer,the maximum stress of chip-off plate tended to decrease.The ballistic performance of nonmetal interlayer structure was better than metal interlayer structure.Glass fiber was an ideal interlayer material,which could block stress wave propagation in the thickness direction and prevent splash of ceramic.