Ballistic impact behaviour of composites: Analytical formulation

A generalised analytical formulation is presented for the prediction of ballistic impact behaviour of 2D woven fabric composite laminates impacted with a rigid cylindrical projectile. The formulation is valid for a wide range of laminate thicknesses. The formulation is based on stress wave propagation and energy balance between the moving projectile and the composite target impacted. During the ballistic impact event, the energy lost by the projectile is absorbed by the target through various damage and energy-absorbing mechanisms such as compression of the target directly below the projectile, compression in the region surrounding the impacted zone, shear plugging, 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, conical deformation on the back face of the target, delamination, matrix cracking, and friction between the moving projectile and the target. The formulation presented considers both shear plugging and tensile failure during conical deformation. Experimental validation is performed on the ballistic impact behaviour of composites. Typical results on ballistic limit velocity and energy absorbed by various mechanisms are presented. Possible methods for the enhancement of ballistic impact performance of the composites are discussed. Typical materials used for ballistic impact protection applications are also presented. With certain modifications, the formulation presented can be used for ballistic impact analysis of 3D woven composites and laminated composites made using unidirectional layers.