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The effects of pile-up, viscoelasticity and hydrostatic stress on polymer matrix nanoindentation

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dc.contributor.author Hardiman, Mark
dc.contributor.author Vaughan, Ted Joseph
dc.contributor.author McCarthy, Conor T.
dc.date.accessioned 2016-10-27T14:00:31Z
dc.date.available 2016-10-27T14:00:31Z
dc.date.issued 2016
dc.identifier.uri http://hdl.handle.net/10344/5307
dc.description peer-reviewed en_US
dc.description.abstract It is well known that a clear disparity exists between the elastic modulus determined using macroscopic tensile testing of polymers and those determined using nanoindentation, with indentation moduli generally overestimating the elastic modulus significantly. The effects of pile-up, viscoelasticity and hydrostatic stress on the indentation modulus of an epoxy matrix material are investigated. An analysis of residual impressions using scanning probe microscopy indicates that material pile-up is insignificant. Viscous effects are negated by increasing the time on the sample during the loading/hold segment phases of the indentation test, and by calculating the contact stiffness at a drift-insensitive point of the unloading curve. Removing the effects of viscous deformation reduces the modulus by 10-13%, while also significantly improving the non-liner curve fitting procedure of the Oliver and Pharr method. The effect of hydrostatic stress on the indentation modulus is characterised using relations from literature, reducing the measured property by 16%. Once viscous and hydrostatic stress effects are accounted for, the indentation modulus of the material compares very well with the bulk tensile modulus, and modifications to standard indentation protocols for polymers are proposed. (C) 2016 The Authors. Published by Elsevier Ltd. en_US
dc.language.iso eng en_US
dc.publisher Elsevier en_US
dc.relation.ispartofseries Polymer Testing;52, pp. 157-166
dc.relation.uri http://dx.doi.org/10.1016/j.polymertesting.2016.04.003
dc.subject nanoindentation en_US
dc.subject pile-up en_US
dc.subject viscoelasticity en_US
dc.subject hydrostatic stress en_US
dc.title The effects of pile-up, viscoelasticity and hydrostatic stress on polymer matrix nanoindentation en_US
dc.type info:eu-repo/semantics/article en_US
dc.type.supercollection all_ul_research en_US
dc.type.supercollection ul_published_reviewed en_US
dc.date.updated 2016-10-27T13:50:03Z
dc.description.version PUBLISHED
dc.identifier.doi 10.1016/j.polymertesting.2016.04.003
dc.contributor.sponsor IRC en_US
dc.contributor.sponsor European Regional Development Fund en_US
dc.contributor.sponsor SFI en_US
dc.relation.projectid 13/1A/1833 en_US
dc.rights.accessrights info:eu-repo/semantics/openAccess en_US
dc.internal.rssid 1645839
dc.internal.copyrightchecked Yes
dc.identifier.journaltitle Polymer Testing
dc.description.status peer-reviewed


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