This work focuses on the effect of strain rate and fibre rotation on the in-plane shear properties of composite laminates. The effect of fibre rotation on the measured shear properties, was for the first time experimentally quantified with the comparison between compression and tension tests of the ±45° laminate samples. Significant increase of shear strength and decrease of final failure strain was observed with the increase in strain rate from 5e-4 1/s to 1300 1/s. The nonlinear constitutive model was developed to simulate the large deformation process, in which the fibre orientation was updated as a function of the in-plane shear strain. The results of this investigation should motivate the updating of procedures for experimental characterization as well as analytical and numerical modelling of in-plane shear response of laminates.

Quasi-static and dynamic experiments are conducted to characterise the mechanical response of a syntactic foam comprising hollow glass microballoons in a polyurethane matrix. Stress versus strain histories are measured in uniaxial tension and compression as well as in pure shear, at strain rates ranging from quasi-static in-situ tests are conducted to visualise the deformation mechanisms in tension and compression. The material displays a pronounced sensitivity to the imposed strain rate and relatively high tensile and shear ductility at both low and high strain rates. A tension/compression asymmetry is displayed in quasi-static tests but is lost at high rates of strain.

Z-pin through-thickness reinforcement is used to improve the impact resistance of composite structures; however, the effect of loading rate on Z-pin behaviour is not well understood. The dynamic response of Z-pins in mode I and II delamination of quasiisotropic IM7/8552 laminates was characterized experimentally in this work. Z-pinned samples were loaded at both quasi-static and dynamic rates, up to a separation velocity of 12m/s. The efficiency of Z-pins in mode I delamination decreased with loading rate, which was mainly due to the change in the pin misalignment, the failure surface morphology and to inertia. The Z-pins failed at small displacements in the mode II loading experiments, resulting in much lower energy dissipation in comparison with the mode I case. The total energy dissipation decreased with increasing loading rate, while enhanced interfacial friction due to failed pins may be largely responsible for the higher energy dissipation in quasi-static experiments.

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A thorough experimental procedure is presented in which the mode II delamination resistance of a laminated fibre reinforced plastic (FRP) composite with and without Zpins is characterised when subjected to increasing strain rates. Standard three-point End Notched Flexure (3ENF) specimens were subjected to increasing displacement loading rates from quasi-static (~0m/s) to high velocity impact (5m/s) using a range of test equipment including drop weight impact tower and a Modified Hopkinson Bar apparatus for dynamic three-point bending tests. The procedure outlined uses compliance based approach to calculate the fracture toughness which was shown to produce acceptable values of GIIC for all loading rates. Using detailed high resolution imaging relationships between delamination velocities, apparent fracture toughness, longitudinal and shear strain rates were measured and compared. Confirming behaviours observed in literature, the thermosetting brittle epoxy composite showed minor increase in GIIC with increase in strain rate. However, the Z-pinned specimens showed a significant increase in the apparent GIIC with loading rate. This highlights the need to consider the strain rate dependency of the Zpinned laminates when designing Z-pinned structures undergoing impact.