Ballistic impact performance of composite targets

Ballistic impact performance of structures made of polymer matrix composites is presented. During the ballistic impact event, the energy lost by the projectile is absorbed by the composite target through various energy absorbing mechanisms. Compression of the target directly below the projectile, compression in the region surrounding the impacted zone, stretching and tensile failure of yarns/layers in the region consisting of primary yarns, tensile deformation of yarns/layers in the region consisting of secondary yarns, delamination, matrix cracking and friction between the projectile and the target are the energy absorbing mechanisms. Additionally, conical deformation on the back face of the target and energy absorbed by the moving cone is the special feature of thin composites whereas energy absorbed by shear plugging of the target is the special feature of thick composites. In the present studies, a generalized approach is used and both shear plugging and tensile failure during conical deformation are considered. The generalized approach used is valid for a wide range of laminate thicknesses. Based on the generalized approach, performance of typical 2D plain weave fabric composites has been presented in this study. Ballistic impact experiments were performed to validate the analytical predictions. The analytical predictions of ballistic limit velocity and plug dimension are found to be in good agreement with the experimental results. Energy absorbed by various mechanisms and variation of projectile velocity and kinetic energy are presented as a function of time. Further, ballistic limit velocity as a function of target thickness has been evaluated. The results obtained show that the ballistic limit velocity increases with the increase in target thickness initially, then remains nearly constant over a range of target thickness. With further increase in target thickness, the ballistic limit velocity increases. (c) 2013 Elsevier Ltd. All rights reserved.