Anti-penetration Performance Of Double-layered Plates With Air Space Struck By A Blunt Rigid Projectile

The application of perforation has played an important role in the field of military use and civil defense. Nowadays, for single-layered plate, it has gained a satisfying achievement by research study, numerical simulation and theoretical analysis.However,the research on double-layered plate is relatively rare.Double-layered plate may either be layered with or without spacing. This thesis mainly focuses on studying perforation modes of double-layered plates with air space struck by a blunt rigid projectile. The detailed researches as follows:1.The test data from 6/12 mm thick monolithic target and(2×6+24)mm thick double-layered target spaced with air impacted by blunt projectiles can be analyzed.The ballistic limit velocity of the target is based on Recht-Ipson formula that can deal with residual versus initial velocities.With the possible exception of air,double-layered targets is regarded as two 6mm thick plates.Plug has an important on terminal ballistic performance.2. The target material, plate thickness and the projectile velocity have a great effect on the terminal ballistic performance, and the shear plugging and adiabatic shear plugging are considered to be the possible perforation modes of single-layered metal plate struck by a blunt rigid projectile. With increasing the thickness of plate and the velocity of projectile, the failure mode of metal plate may transform from shear plugging to adiabatic shear plugging. Thus regarding the perforation of double-layered or multi-layered plates, the failure modes of various plates may be quite different. Further experimental analyses are conducted on the perforations of single and double-layered Weldox E steel plates with air space to discuss the different perforation modes. It indicates that, in case of higher initial striking velocity, the failure mode of the first layer plate is adiabatic shear plugging, whilst the failure mode of the second layer plate is adiabatic shear plugging or shear plugging as the striking velocity of the projectile slows down. It concludes that the final failure mode of the double-layered plates is the mixture of shear plugging and adiabatic shear plugging.3. Through numerical simulation, 6/12 mm thick monolithic target and(2×6+24)mm thick double-layered target spaced with air space impacted by bluntprojectiles is analyzed. The ballistic limit velocities of the three targets by comparison to prediction of residual velocity and test data are based on Recht-Ipson formula that can deal with residual versus initial velocities.Numerical simulation concludes that the final failure mode of the double-layered plates spaced with air is the mixture of shear plugging and adiabatic shear plugging,which coincide with the theoretic analysis.