Compressive Failure of Hybrid Laminate Composites

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dc.contributor.advisor Battley, M en Clements, Madeleine en 2018-08-09T23:35:27Z en 2018 en
dc.identifier.uri en
dc.description Full Text is available to authenticated members of The University of Auckland only. en
dc.description.abstract Carbon fibre reinforced polymers are very stiff, strong and lightweight materials. Sailing yacht masts are primarily compressively loaded stiffness critical structures, with local areas of high-strength requirements. However, carbon fibre laminates are subject to a stiffness-strength trade-off, as the stiffness of the fibres increases, their strength decreases. A combination of different stiffness fibres within a laminate offers an opportunity to optimise strength and stiffness of a composite laminate for varying load conditions. Laminates with such a combination are referred to as ‘hybrid laminates’. This research aims to investigate how hybridisation of laminates affect failure initiation and propagation under compressive loads, use models of hybrid laminates to investigate internal ply stresses and strains at failure and find a reliable model of strength prediction for these laminates. Physical testing was undertaken of compressively loaded hybrid laminates with varying proportions of High Modulus and Ultra-High Modulus fibres. Specimens with 3mm holes were also tested to determine the effect of hybridisation in the presence of a stress concentration. Failure events within both specimen types were monitored through Acoustic Emission testing and high-speed imaging. Specimens with 50% and 66% of on-axis Ultra-High Modulus plies were shown to out-perform High Modulus laminates in terms of strength, while still retaining the expected stiffness. Other laminates were shown to fail at the failure strain of Ultra-High Modulus laminae. In specimens with a hole, the stress concentration was shown to dominate failure, with all laminates failing at the expected strength of the lowest strength ply. The test results were used to validate Finite Element and Classical Lamination theory models. These models enabled investigation of internal ply stresses and strains, as well as exploration of the effects of hybridisation on interlamina stresses. The model results showed that High Modulus, 50% (D) and 66% on axis UHM laminates failed at the stress expected for HM ply failure, while 33%, 50% 100% and UHM laminates failed at the stress expected UHM ply failure. Finally, an analysis of common failure prediction models on the basis of High Modulus or Ultra-High Modulus ply failure was undertaken, and compared to the actual failure stress. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.relation.isreferencedby UoA99265093807802091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights Restricted Item. Full Text is available to authenticated members of The University of Auckland only. en
dc.rights.uri en
dc.rights.uri en
dc.title Compressive Failure of Hybrid Laminate Composites en
dc.type Thesis en Engineering Science en The University of Auckland en Masters en
dc.rights.holder Copyright: The author en
pubs.elements-id 751254 en
pubs.record-created-at-source-date 2018-08-10 en

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