Deformation and collapse of orthogonal 3D woven composites: quasi-static and impact loading

This thesis presents an experimental and numerical investigation undertaken in order to develop the understanding of the behaviour of orthogonal 3D woven composites under quasi-static tension/compression, out-of-plane bending and dynamic soft and multi-hit ballistic impact load cases. Focus is given to the deformed configuration of samples, and to the initiation and propagation of damage within the material. The damage mitigation properties of the through-the-thickness (TTT) reinforcement are highlighted throughout. A pressurised gas gun test system was developed at the University of Nottingham in order to undertake the soft and ballistic impact tests upon 3D woven composite samples. Experimental and numerical comparisons are made to similar UD-laminate composite materials. An established continuum damage mechanics framework is employed for numerical modelling of the quasi-static and soft impact load cases, allowing for further insights into the experimental results. A review of the efficacy of the numerical modelling strategy is presented, alongside a study on the influence of the TTT reinforcement on the out-of-plane static and dynamic response of the material. The numerical modelling strategy is then adapted for ballistic impact events. A numerical study is conducted on the multi-hit ballistic impact properties of orthogonal 3D woven composites, the first of its kind. Comparisons are made between experimental ballistic impact experiments and numerical calculations