UBC Theses and Dissertations
An engineering approach to modelling the impact and ballistic response of laminated composite structures Quan, Xiangyang
A super finite element program, SENACS, that was previously developed for transient nonlinear analysis of isotropic structures, has been modified to handle the structural response of layered (laminated) composite materials. Both material and geometric non-linearities have been taken into account in the formulation. The structural analysis capabilities of the code have been demonstrated by successfully comparing the predictions with other experimental, analytical, and numerical results in the literature. Impact problems have been subdivided into two groups: nonpenetrating and penetrating. In each case, appropriate contact laws are introduced to evaluate the local impact load on the structure while the structural analysis part of SENACS computes the target global response. In nonpenetrating impact events, where there is only elastic indentation in the targets, the Hertzian contact law has been employed to establish the impact force as a function of the local indentation. Predictions of the nonpenetrating impact response of plain and stiffened laminated composite plate and shell structures have been found to be in good agreement with the experimental measurements previously reported in the literature. Modelling of penetrating impact problems has been guided by experimental investigations. A phenomenological analytical model for static penetration of composite materials has been developed. In this model, three major penetration mechanisms have been accounted for: hole expansion, flexural deformation of a delaminated plate (split-plate), and transverse plugging. The parameters of the model have been determined through material characterisation tests. The penetration model is introduced as a local contact behaviour in SENACS, and used to predict the penetrating impact response of composites to projectiles with different conical nose shapes. Ballistic impact response of two different material systems, IM7/8551-7 Carbon Fibre-Reinforced Polymer (CFRP) and S2-glass/phenolic resin Glass Fibre- Reinforced Polymer (GFRP) laminates provides the physical background and experimental verifications for the present model. Finally, a number of numerical ballistic simulations have been carried out to investigate the influence of structural shapes and sizes, loading conditions, projectile geometry, and impact velocity on the energy absorption capability of composite materials.