Cargando…
An Assessment of the Effect of Progressive Water Absorption on the Interlaminar Strength of Unidirectional Carbon/Epoxy Composites Using Acoustic Emission
Carbon Fibre-Reinforced Polymers (CFRPs) in aerospace applications are expected to operate in moist environments where carbon fibres have high resistance to water absorption; however, polymers do not. To develop a truly optimised structure, it is important to understand this degradation process. Thi...
Autores principales: | , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2021
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8271434/ https://www.ncbi.nlm.nih.gov/pubmed/34202169 http://dx.doi.org/10.3390/s21134351 |
_version_ | 1783721001323855872 |
---|---|
author | Almudaihesh, Faisel Grigg, Stephen Holford, Karen Pullin, Rhys Eaton, Mark |
author_facet | Almudaihesh, Faisel Grigg, Stephen Holford, Karen Pullin, Rhys Eaton, Mark |
author_sort | Almudaihesh, Faisel |
collection | PubMed |
description | Carbon Fibre-Reinforced Polymers (CFRPs) in aerospace applications are expected to operate in moist environments where carbon fibres have high resistance to water absorption; however, polymers do not. To develop a truly optimised structure, it is important to understand this degradation process. This study aims to expand the understanding of the role of water absorption on fibrous/polymeric structures, particularly in a matrix-dominant property, namely interlaminar strength. This work used Acoustic Emission (AE), which could be integrated into any Structural Health Monitoring System for aerospace applications, optical strain measurements, and microscopy to provide an assessment of the gradual change in failure mechanisms due to the degradation of a polymer’s structure with increasing water absorption. CFRP specimens were immersed in purified water and kept at a constant temperature of 90 °C for 3, 9, 24 and 43 days. The resulting interlaminar strength was investigated through short-beam strength (SBS) testing. The SBS values decreased as immersion times were increased; the decrease was significant at longer immersion times (up to 24.47%). Failures evolved with increased immersion times, leading to a greater number of delaminations and more intralaminar cracking. Failure modes, such as crushing and multiple delaminations, were observed at longer immersion times, particularly after 24 and 43 days, where a pure interlaminar shear failure did not occur. The observed transition in failure mechanism showed that failure of aged specimens was triggered by a crushing of the upper surface plies leading to progressive delamination at multiple ply interfaces in the upper half of the specimen. The crushing occurred at a load below that required to initiate a pure shear failure and hence represents an under prediction of the true SBS of the sample. This is a common test used to assess environmental degradation of composites and these results show that conservative knockdown factors may be used in design. AE was able to distinguish different material behaviours prior to final fracture for unaged and aged specimens suggesting that it can be integrated into an aerospace asset management system. AE results were validated using optical measurements and microscopy. |
format | Online Article Text |
id | pubmed-8271434 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-82714342021-07-11 An Assessment of the Effect of Progressive Water Absorption on the Interlaminar Strength of Unidirectional Carbon/Epoxy Composites Using Acoustic Emission Almudaihesh, Faisel Grigg, Stephen Holford, Karen Pullin, Rhys Eaton, Mark Sensors (Basel) Article Carbon Fibre-Reinforced Polymers (CFRPs) in aerospace applications are expected to operate in moist environments where carbon fibres have high resistance to water absorption; however, polymers do not. To develop a truly optimised structure, it is important to understand this degradation process. This study aims to expand the understanding of the role of water absorption on fibrous/polymeric structures, particularly in a matrix-dominant property, namely interlaminar strength. This work used Acoustic Emission (AE), which could be integrated into any Structural Health Monitoring System for aerospace applications, optical strain measurements, and microscopy to provide an assessment of the gradual change in failure mechanisms due to the degradation of a polymer’s structure with increasing water absorption. CFRP specimens were immersed in purified water and kept at a constant temperature of 90 °C for 3, 9, 24 and 43 days. The resulting interlaminar strength was investigated through short-beam strength (SBS) testing. The SBS values decreased as immersion times were increased; the decrease was significant at longer immersion times (up to 24.47%). Failures evolved with increased immersion times, leading to a greater number of delaminations and more intralaminar cracking. Failure modes, such as crushing and multiple delaminations, were observed at longer immersion times, particularly after 24 and 43 days, where a pure interlaminar shear failure did not occur. The observed transition in failure mechanism showed that failure of aged specimens was triggered by a crushing of the upper surface plies leading to progressive delamination at multiple ply interfaces in the upper half of the specimen. The crushing occurred at a load below that required to initiate a pure shear failure and hence represents an under prediction of the true SBS of the sample. This is a common test used to assess environmental degradation of composites and these results show that conservative knockdown factors may be used in design. AE was able to distinguish different material behaviours prior to final fracture for unaged and aged specimens suggesting that it can be integrated into an aerospace asset management system. AE results were validated using optical measurements and microscopy. MDPI 2021-06-25 /pmc/articles/PMC8271434/ /pubmed/34202169 http://dx.doi.org/10.3390/s21134351 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Almudaihesh, Faisel Grigg, Stephen Holford, Karen Pullin, Rhys Eaton, Mark An Assessment of the Effect of Progressive Water Absorption on the Interlaminar Strength of Unidirectional Carbon/Epoxy Composites Using Acoustic Emission |
title | An Assessment of the Effect of Progressive Water Absorption on the Interlaminar Strength of Unidirectional Carbon/Epoxy Composites Using Acoustic Emission |
title_full | An Assessment of the Effect of Progressive Water Absorption on the Interlaminar Strength of Unidirectional Carbon/Epoxy Composites Using Acoustic Emission |
title_fullStr | An Assessment of the Effect of Progressive Water Absorption on the Interlaminar Strength of Unidirectional Carbon/Epoxy Composites Using Acoustic Emission |
title_full_unstemmed | An Assessment of the Effect of Progressive Water Absorption on the Interlaminar Strength of Unidirectional Carbon/Epoxy Composites Using Acoustic Emission |
title_short | An Assessment of the Effect of Progressive Water Absorption on the Interlaminar Strength of Unidirectional Carbon/Epoxy Composites Using Acoustic Emission |
title_sort | assessment of the effect of progressive water absorption on the interlaminar strength of unidirectional carbon/epoxy composites using acoustic emission |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8271434/ https://www.ncbi.nlm.nih.gov/pubmed/34202169 http://dx.doi.org/10.3390/s21134351 |
work_keys_str_mv | AT almudaiheshfaisel anassessmentoftheeffectofprogressivewaterabsorptionontheinterlaminarstrengthofunidirectionalcarbonepoxycompositesusingacousticemission AT griggstephen anassessmentoftheeffectofprogressivewaterabsorptionontheinterlaminarstrengthofunidirectionalcarbonepoxycompositesusingacousticemission AT holfordkaren anassessmentoftheeffectofprogressivewaterabsorptionontheinterlaminarstrengthofunidirectionalcarbonepoxycompositesusingacousticemission AT pullinrhys anassessmentoftheeffectofprogressivewaterabsorptionontheinterlaminarstrengthofunidirectionalcarbonepoxycompositesusingacousticemission AT eatonmark anassessmentoftheeffectofprogressivewaterabsorptionontheinterlaminarstrengthofunidirectionalcarbonepoxycompositesusingacousticemission AT almudaiheshfaisel assessmentoftheeffectofprogressivewaterabsorptionontheinterlaminarstrengthofunidirectionalcarbonepoxycompositesusingacousticemission AT griggstephen assessmentoftheeffectofprogressivewaterabsorptionontheinterlaminarstrengthofunidirectionalcarbonepoxycompositesusingacousticemission AT holfordkaren assessmentoftheeffectofprogressivewaterabsorptionontheinterlaminarstrengthofunidirectionalcarbonepoxycompositesusingacousticemission AT pullinrhys assessmentoftheeffectofprogressivewaterabsorptionontheinterlaminarstrengthofunidirectionalcarbonepoxycompositesusingacousticemission AT eatonmark assessmentoftheeffectofprogressivewaterabsorptionontheinterlaminarstrengthofunidirectionalcarbonepoxycompositesusingacousticemission |