dc.contributor.advisor |
Battley, M |
en |
dc.contributor.author |
Bailey, Nathan |
en |
dc.date.accessioned |
2014-05-22T21:51:58Z |
en |
dc.date.issued |
2014 |
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dc.identifier.uri |
http://hdl.handle.net/2292/22135 |
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dc.description.abstract |
The increased use of composite sandwich structures in aeronautical applications presents many design and certi cation challenges. The aim of this thesis is to characterise the dynamic tolerance of aeronautical sandwich structures subjected to compression loads. Aircraft structures are designed to withstand a dynamic load typical of a survivable crash scenario which can cause materials to behave di erently compared to static loading. A representative sandwich structure commonly used in aircraft has been used for the investigation, comprised of glass bre phenolic resin facesheets and Nomex honeycomb core. Experimental techniques have been developed using drop weight impact, split Hopkinson pressure bar, and servo-hydraulic systems to characterise the dynamic edgewise compression properties for strain rates between 1.0 s 1 and 50 s 1. Results demonstrated the signi cant e ect of the applied strain rate on the response of the structure, including a 37 % increase in edgewise compressive strength for undamaged specimens loaded at a strain rate of 15 s 1. Quasi-static indentation was used for the creation of pre-damage with indentations of 1 mm, 2 mm and 3 mm. Specimens were then subjected to dynamic edgewise compression and high speed photography was used to capture the failure mechanisms. Dynamic edgewise compression at a strain rate of 15 s 1 showed the residual strength of pre-damaged specimens was 54.8 %. 48.9 % and 57.3 % greater than static residual strength, for the 1 mm, 2 mm and 3 mm damage cases respectively. Dynamic edgewise compression of undamaged specimens caused substantial crack branching in the facesheets at failure. Pre-damaged specimens subjected to dynamic edgewise compression showed increased levels of core indentation at the pre-damage region prior to nal failure of the facesheet. Finite element analysis was used to develop a two-step simulation model of damage creation and residual strength. The honeycomb core was modelled as a discrete cell lattice, enabling capture of failure mechanisms observed in the experimental investigations. Predictions of static and dynamic compression strength di ered by 9.3 % to 35.1 % compared to the experimental results, depending on the strain rate and pre-damage being considered. The results demonstrate that static characterisation of honeycomb sandwich structures does not accurately capture the dynamic force response and mechanisms of failure. The experimental and numerical methods in this thesis provide insight into the dynamic edgewise response of composite sandwich structures to aid in the design and development of future aeronautical structures. |
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dc.publisher |
ResearchSpace@Auckland |
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dc.relation.ispartof |
PhD Thesis - University of Auckland |
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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. |
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dc.rights.uri |
https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm |
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dc.rights.uri |
http://creativecommons.org/licenses/by-nc-sa/3.0/nz/ |
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dc.title |
Damage Tolerance of Aeronautical Sandwich Structures Subjected to Dynamic Compression Loads |
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dc.type |
Thesis |
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thesis.degree.grantor |
The University of Auckland |
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thesis.degree.level |
Doctoral |
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thesis.degree.name |
PhD |
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dc.rights.holder |
Copyright: The Author |
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dc.rights.accessrights |
http://purl.org/eprint/accessRights/OpenAccess |
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pubs.elements-id |
439657 |
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pubs.record-created-at-source-date |
2014-05-23 |
en |
dc.identifier.wikidata |
Q112904501 |
|