Highly instrumented static, dynamic, and impact testing of high performance materials

Abstract

This thesis presents an investigation into potential improvements in the ballistic performance of high performance composite materials by hybridizing them with other polymer materials. The main focus is on extraction of quantitative information from ballistic trials with armour grade composite materials. The primary goal of the research in this thesis is to understand the behaviour of high performance composites and polymer materials during ballistic impact events. To design a novel hybrid composite material system, an in-depth knowledge of the hybrid material constituents must be gained. The research performed to meet this objective is presented in this thesis and is divided into four main parts, preceded by a literature review of these topics (Chapter 2). It is believed that the ballistic performance of armour grade composite materials is dependent to a certain extent on the tensile properties of the reinforcement phase (i.e. fibres). Therefore, the first part of the thesis (Chapter 3) presents an evaluation of the static tensile yarn performance of 16 different high tenacity fibres. The goal of part two of the research was to evaluate dynamic properties of the same fibres in dynamic conditions by means of a tensile split Hopkinson bar. Chapter 4 presents conclusions from the experiments employing standard Hopkinson pressure bar for fibre testing. The third part of the thesis (Chapter 5) focuses on the evaluation of the ballistic performance of various materials which could be utilized in a hybrid armour system. A highly instrumented ballistic setup was established to measure armour deformation characteristics during the impact event. The measured ballistic data allowed the derivation of the ballistic limit of each material system and for a relative comparison of the ballistic performance between the different material systems and their applicability as an armour. The damage within the ballistic panels were further investigated using Computed Tomography and Computed Laminography scans. The final part of this thesis (Chapter 6) presents studies dedicated to the design of novel material systems of improved ballistic performance. A wide range of hybrids were investigated and conclusions drawn on the optimum route to improve the ballistic limit of a polymer amour system.