Finite Element Analysis of Composites Integral Armour

Abstract

This thesis is focussed on a numerical method to analyse the ballistic performance of multi-material armour system. The overall objective of this work is to develop numerical models to be used within MSC. DYTRAN capable of accurately predicting the ballistic response of multi-material composite armour, the effect of impact type on the damage and to help improve the armour design. The research presented in this thesis includes a review of the existing ceramic and composite damage models, combine, modify and optimize them to investigate the type and extent of damage response of the materials used in ballistic protection. The numerical model leads to insight into the parameters governing the penetration and deformation response of laminated composite subjected to ballistic impact. The effect of various model parameters on the predicted ballistic response of the ballistic plate is intensively investigated. It was found that the through thickness properties used in the numerical model have a large effect on the predicted ballistic response. A detailed study of the effect of mesh density on the numerical solution has shown that the numerical predictions are highly influenced by the element shape and size. The smaller the element the sooner the failure occurs, the less energy is absorbed and the smaller the time step becomes leading to a larger simulation time. The accuracy of the composite numerical model was evaluated by comparing the numerical prediction to experimental data obtained from ballistic impact trials. Very good agreement has been found between the experimental and numerical results for both observations of damage and deformation. Further, values of measured ballistic limit are in very good agreement with the values gained from the simulations. This correlation forms a verification of our finite element simulations. Fibre breakage is generally acknowledged as the main energy absorption mechanism in damage due to ballistic impact; in this work the delamination and matrix failure have been shown to increasingly contribute to the energy absorption mechanism by reducing the matrix strength. Further study of multi-layered ceramic composite armour has shown that use of ceramic tiles can improve the ballistic protection of the armour within an optimum ceramic composite ratio. Finite element simulation has been shown to be a very powerful technique to predict the behaviour of composite and ceramic panels under ballistic impact.