Theory And Experiment Investigation On The Failure Mechanisms And Ballistic Performance Of Ceramic Composite Armor

Due to its high compressive strength, high hardness and low density, etc, ceramic plays a very important role in enhancing the ballistic performance of composite armor, and has been widely used. A serials of results in the research of failure mechanism and ballistic performance of ceramic composite armor has been obtained, however, the 'failure mechanism and ballistic performance is related to many factors such as the projectile velocity, armor structure,ceramic's thickness, material of cover plate and support plate, etc.Therefore, there is very important scientific signficance and engineering application value in researching the failure mechanism and ballistic performance of ceramic composite armor. Based on reviewing the research history of ceramic composite armor and analysing of remaining problems, this paper reaearched the failure mechanism and ballistic performance of ceramic composite armor both in using theory methods and experiment analysis with taking AD95 ceramic as the research model.Firstly, based on the theory of cavity expansion, this paper drived quasi-static spherical and cylindrical cavity expansion model and dynamic spherical cavity expansion model of ceramic using elastic-brittle constitutive model obeying the bilinear idenlization of the two curve pressure shear behavior and Mohr-Coulomb yield criterion. Followed in order to AD95 ceramic material parameters as the basic parameters, the influence of the pressure-shear coefficient, compressive strength, tensile strength, relative desity and projectile impact velocity to the ceramic cavity expansion pressure is analysed. The result showed that ceramic cavity expansion pressure increased with the increasing of the pressure-shear coefficient,compressive strength,tensile strength, relative desity and projectile impact velocity,and the influence of pressure-shear coefficient and compressive strength is relatively larger than the other parameters'.Secondly, based on the cavity expansion pressure which was calculated in the previous chapter, this paper got the penetration resistance of projectile by solving the equation of oval warhead jets penetration. Further more, this paper predicted the penetration depth of the tungsten alloy projectile penetrating AIN and AD95 ceramic, which matched the experimental results very well. The the relationship of penetration depth and projectile impact velocity and the target's resistance was anlysed. It was showed that the penetration depth is increasing with the increase of the projectile velocity, but there is a top velocity, and the penetration depth is decreasing with the increase of the target's resistance.With the cavity expansion model,the relative parameters were presented. What's more, this paper showed the time history curve of penetration depth, projectile velocity and the remaining length of projectile with time. Finally, we summarized the shortage of the A-T model and cavity expansion model. Based on the shortage, we put forward the experiment project.Finally, an experimental investigation has been performed to study the failure mechanisms and ballistic performance of AD95 alumina ceramic/metal composite armor with various boundary conditions, and also verified the cavity expansion model. The tungalloy projectile was launched by a two stage light gas gun, and the impact velocity was 720±20m/s. The interface pressure of the ceramic back side was tested by manganin stress gauges.The result is 288.8KN, which is very close to the value calculated by the cavity expansion theory. So, the cavity expansion model was verified. Combining the cavity expansion theory with the experiment results, we analysed the process of the penetration, the factors which influenced the failure mechanism and ballistic performance of composite armor. It was showed that the ceramic armor resisted the penetration of projectile by smashing the ceramic. This paper also researched the effect of each factor of the ceramic composite armor to the ballistic performance using transformative mass efficiency and relative differential efficiency factor. From the result, we can kow that perfect bound format, using high-strength materials to cover plate, increasing the thickness of ceramic board/support plate can enhance the ballistic performance of ceramic composite armor.