Browsing by Author "Aspinall, Timothy"
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Item Open Access Influence of carbon fibre orientation on the post-fire tensile behaviour of carbon fibre reinforced polymer (CFRP) laminates(Cranfield University, 2023-03-16T14:47:43Z) Aspinall, TimothyThe effect of carbon fibre orientation on the post-fire tensile behaviour of carbon fibre-reinforced polymer (CFRP) laminates is investigated in this study. CFRP specimens produced using unique carbon fibre orientations, unidirectional, bidirectional and multidirectional denoted S1, S2 and S3, respectively, are compared before and after exposure to thermal exposure. This study has practical usefulness as CFRP laminates containing these types of carbon fibre orientations are often utilised adjacent or close to fuel storage in aircraft that may present a fire hazard. The study's results showed that the S1 specimens exhibited the highest resistance to tensile failure before and after thermal exposure, whereas the S3 specimens exhibited the lowest resistance to tensile failure before and after thermal exposure. Furthermore, the data has shown that after thermal exposure, the tensile properties of the S1, S2 and S3 CFRP specimens reduced by 35%, 51% and 52%, respectively, compared to before thermal exposure. This loss in tensile properties can be attributed to the pyrolysis of the epoxy matrix and subsequent loss of interfacial bond strength, as the irradiance intensity used in the study was purposely chosen to represent the heat from a fire due to a small fuel leak in an aircraft resulting in temperatures lower than those required to oxidise the carbon fibres. Post-fire imagery has also shown that all the specimens in their undamaged state exhibit brittle failure; however, after thermal exposure, all CFRP specimens exhibit explosive delamination failure.Item Open Access The Thermomechanical Behaviour of Carbon Fibre Reinforced Polymer in a Fire(Cranfield University, 2020-12-07 16:29) Aspinall, TimothyThe effect of fire on military aircraft is a large factor in assessing their survivability and understanding this is a complex and challenging task, which requires specialist research. Quantifying the thermomechanical behaviour of Carbon Fibre Reinforced Polymers (CFRP) used in aircraft structural components is an essential required step to determine their structural integrity when exposed to fire. The thermomechanical response leading to the loss of mechanical properties is governed by the glass transition, thermal decomposition (pyrolysis) of the resin matrix and oxidation of the carbon fibre reinforcement. These phenomena are strongly coupled and their effect on the mechanical response of CFRP are poorly documented in the literature.This work presents the development of a low-cost method for investigating the thermomechanical properties of such materials in terms of displacement and failure time under constant load. The work has centred on, an experimental study which is designed to quantify the thermomechanical behaviour of CFRP during three-point bending under different thermal exposures. Of particular interest was the contribution to the failure mechanism of the propagation of the glass transition isotherm through the sample and fibre oxidation on the exposed surface of the samples. Consequently, the results can be used to assess the understanding of failure modes of CFRP in loadbearing structural components of military aircraft.