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Relating moisture ingress to component strength and stiffness for carbon-fibre composites. / Joanne Maureen Ryan

Swansea University Author: Joanne Maureen Ryan

Abstract

Moisture diffusion studies were performed using unidirectional (UD) tape and quasiisotropic (QI) woven 5-harness satin fabric, carbon fibre reinforced (CFR) epoxy composite materials. Firstly the moisture constants, (i.e. diffusion coefficient, D[x], and equilibrium moisture content, M[max]) were ex...

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Published: 2011
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42389
first_indexed 2018-08-02T18:54:35Z
last_indexed 2018-08-03T10:10:01Z
id cronfa42389
recordtype RisThesis
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To investigate moisture absorption as a function of %RH test coupons were conditioned to differing equilibrium moisture levels viz., 70&amp;deg;C/60%RH, 70&amp;deg;C/75%RH, 70&amp;deg;C/85%RH, and 70&amp;deg;C/95%RH. Also oven dry (OD) and as-received (AR) tests were performed for baseline comparison. The effect of moisture absorption on the mechanical behaviour was investigated; lamina properties were studied by measuring tension, compression, shear (inter/intralaminar) strength and stiffness of the UD material. This comprehensive set of testing provided quantitative relationships between moisture content and mechanical properties. The quasi-isotropic lay-up was then utilised to investigate multi-directional laminate lay-ups using open hole tension and compression testing. The experimental data showed that the uptake of moisture in both the materials studied was described well by Fick's Second Law and the properties most affected by moisture ingress were matrix-dominated properties. More specifically, the transverse tensile strength, F[t][2] was most affected by the ingress of moisture, with a near 50% reduction in strength when conditioned to equilibrium moisture content at 70&amp;deg;C/95%RH. Such information is a necessary prerequisite if improved design procedures are going to be developed in the future. The initial phase of testing produced mechanical property/moisture relationships that were employed to predict the strength and stiffness of the material containing specific moisture gradients through-the-thickness (TTT). To be able to predict mechanical properties with different moisture distribution, firstly moisture distribution TTT of the material was modelled using an analytical solution to Fick's Second Law. Then moisture content was considered on a ply-by-ply basis TTT of the laminate; reductions were applied to each individual ply property dependent on the moisture content using the experimentally derived relationships, essentially applying environmental knock-down factors (KEKDF'S) to each individual ply. Classical Laminate Analysis (CLA) was then performed using the Max Stress failure criteria in order to predict the overall laminate failure. A second phase of mechanical testing was then performed to validate these predictions. The mechanical property predictions compared well to the experimental data showing similar reductions in strength for a given profile of moisture in the laminate. 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spelling 2018-08-02T16:24:29.0569807 v2 42389 2018-08-02 Relating moisture ingress to component strength and stiffness for carbon-fibre composites. 5b767058e981afe06cacc1f651052f9f NULL Joanne Maureen Ryan Joanne Maureen Ryan true true 2018-08-02 Moisture diffusion studies were performed using unidirectional (UD) tape and quasiisotropic (QI) woven 5-harness satin fabric, carbon fibre reinforced (CFR) epoxy composite materials. Firstly the moisture constants, (i.e. diffusion coefficient, D[x], and equilibrium moisture content, M[max]) were experimentally derived at 70&deg;C and 85% relative humidity (%RH), for the two CFR materials. To investigate moisture absorption as a function of %RH test coupons were conditioned to differing equilibrium moisture levels viz., 70&deg;C/60%RH, 70&deg;C/75%RH, 70&deg;C/85%RH, and 70&deg;C/95%RH. Also oven dry (OD) and as-received (AR) tests were performed for baseline comparison. The effect of moisture absorption on the mechanical behaviour was investigated; lamina properties were studied by measuring tension, compression, shear (inter/intralaminar) strength and stiffness of the UD material. This comprehensive set of testing provided quantitative relationships between moisture content and mechanical properties. The quasi-isotropic lay-up was then utilised to investigate multi-directional laminate lay-ups using open hole tension and compression testing. The experimental data showed that the uptake of moisture in both the materials studied was described well by Fick's Second Law and the properties most affected by moisture ingress were matrix-dominated properties. More specifically, the transverse tensile strength, F[t][2] was most affected by the ingress of moisture, with a near 50% reduction in strength when conditioned to equilibrium moisture content at 70&deg;C/95%RH. Such information is a necessary prerequisite if improved design procedures are going to be developed in the future. The initial phase of testing produced mechanical property/moisture relationships that were employed to predict the strength and stiffness of the material containing specific moisture gradients through-the-thickness (TTT). To be able to predict mechanical properties with different moisture distribution, firstly moisture distribution TTT of the material was modelled using an analytical solution to Fick's Second Law. Then moisture content was considered on a ply-by-ply basis TTT of the laminate; reductions were applied to each individual ply property dependent on the moisture content using the experimentally derived relationships, essentially applying environmental knock-down factors (KEKDF'S) to each individual ply. Classical Laminate Analysis (CLA) was then performed using the Max Stress failure criteria in order to predict the overall laminate failure. A second phase of mechanical testing was then performed to validate these predictions. The mechanical property predictions compared well to the experimental data showing similar reductions in strength for a given profile of moisture in the laminate. The predicted strengths also fell within the measured standard deviation of the experimental data in a significant proportion of the results. E-Thesis Materials science.;Textile research. 31 12 2011 2011-12-31 COLLEGE NANME Engineering COLLEGE CODE Swansea University Doctoral Ph.D 2018-08-02T16:24:29.0569807 2018-08-02T16:24:29.0569807 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised Joanne Maureen Ryan NULL 1 0042389-02082018162450.pdf 10798097.pdf 2018-08-02T16:24:50.5700000 Output 24424945 application/pdf E-Thesis true 2018-08-02T16:24:50.5700000 false
title Relating moisture ingress to component strength and stiffness for carbon-fibre composites.
spellingShingle Relating moisture ingress to component strength and stiffness for carbon-fibre composites.
Joanne Maureen Ryan
title_short Relating moisture ingress to component strength and stiffness for carbon-fibre composites.
title_full Relating moisture ingress to component strength and stiffness for carbon-fibre composites.
title_fullStr Relating moisture ingress to component strength and stiffness for carbon-fibre composites.
title_full_unstemmed Relating moisture ingress to component strength and stiffness for carbon-fibre composites.
title_sort Relating moisture ingress to component strength and stiffness for carbon-fibre composites.
author_id_str_mv 5b767058e981afe06cacc1f651052f9f
author_id_fullname_str_mv 5b767058e981afe06cacc1f651052f9f_***_Joanne Maureen Ryan
author Joanne Maureen Ryan
author2 Joanne Maureen Ryan
format E-Thesis
publishDate 2011
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 1
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description Moisture diffusion studies were performed using unidirectional (UD) tape and quasiisotropic (QI) woven 5-harness satin fabric, carbon fibre reinforced (CFR) epoxy composite materials. Firstly the moisture constants, (i.e. diffusion coefficient, D[x], and equilibrium moisture content, M[max]) were experimentally derived at 70&deg;C and 85% relative humidity (%RH), for the two CFR materials. To investigate moisture absorption as a function of %RH test coupons were conditioned to differing equilibrium moisture levels viz., 70&deg;C/60%RH, 70&deg;C/75%RH, 70&deg;C/85%RH, and 70&deg;C/95%RH. Also oven dry (OD) and as-received (AR) tests were performed for baseline comparison. The effect of moisture absorption on the mechanical behaviour was investigated; lamina properties were studied by measuring tension, compression, shear (inter/intralaminar) strength and stiffness of the UD material. This comprehensive set of testing provided quantitative relationships between moisture content and mechanical properties. The quasi-isotropic lay-up was then utilised to investigate multi-directional laminate lay-ups using open hole tension and compression testing. The experimental data showed that the uptake of moisture in both the materials studied was described well by Fick's Second Law and the properties most affected by moisture ingress were matrix-dominated properties. More specifically, the transverse tensile strength, F[t][2] was most affected by the ingress of moisture, with a near 50% reduction in strength when conditioned to equilibrium moisture content at 70&deg;C/95%RH. Such information is a necessary prerequisite if improved design procedures are going to be developed in the future. The initial phase of testing produced mechanical property/moisture relationships that were employed to predict the strength and stiffness of the material containing specific moisture gradients through-the-thickness (TTT). To be able to predict mechanical properties with different moisture distribution, firstly moisture distribution TTT of the material was modelled using an analytical solution to Fick's Second Law. Then moisture content was considered on a ply-by-ply basis TTT of the laminate; reductions were applied to each individual ply property dependent on the moisture content using the experimentally derived relationships, essentially applying environmental knock-down factors (KEKDF'S) to each individual ply. Classical Laminate Analysis (CLA) was then performed using the Max Stress failure criteria in order to predict the overall laminate failure. A second phase of mechanical testing was then performed to validate these predictions. The mechanical property predictions compared well to the experimental data showing similar reductions in strength for a given profile of moisture in the laminate. The predicted strengths also fell within the measured standard deviation of the experimental data in a significant proportion of the results.
published_date 2011-12-31T04:21:27Z
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score 11.098272

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