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Damage in CFRP composites subjected to simulated lighting strikes - Assessment of thermal and mechanical responses

Damage in CFRP composites subjected to simulated lighting strikes - Assessment of thermal and mechanical responses
Damage in CFRP composites subjected to simulated lighting strikes - Assessment of thermal and mechanical responses
Damage is inflicted upon Carbon Fiber Reinforced Polymer (CFRP) composite laminates using simulated lightning strikes to investigate the resulting residual mechanical properties. Seven different CFRP laminate specimens were exposed to simulated lightning strikes using three different electric waveforms. The three waveforms imposed were the 10/350 μs waveform, which simulates the first return stroke during a direct strike according to IEC 61400–24 Ed1.0. The second was a unipolar long stroke component, and the third was a combination of the first return stroke and the long stroke. After exposure to lightning, coupon specimens were prepared for mechanical testing. The test specimens were subsequently subjected to compression and shear loading to determine the post-strike mechanical properties. The compression tests were conducted using uniaxial coupons in accordance with ASTM standard D6641. The shear tests were conducted using V-notch specimens utilizing an Iosipescu test rig in accordance with ASTM standard D5379. Digital Image Correlation was used to capture the strain fields on the surface of the specimens. The results of the material coupon tests are compared with test results from pristine CFRP coupon samples that were not exposed to any electrical current. The shear and compression strengths, compressive and shear stress-strain curves, compressive and shear moduli, and the maximum temperature on the CFRP specimens during lightning tests are presented and discussed. Key results include that the largest reduction of strength occurred in the specimens that were subjected to the largest current and specific energy. The specific energy correlated more closely to the observed reduction of residual strength than the charge, and the damaged specimens displayed a higher degree of nonlinear stress-strain behavior than the pristine specimens.
CFRP composites, Lightning damage, Wind turbine blades, Compression and shear testing, Thermal imaging, Digital image correlation (DIC), Failure initiation stress
1359-8368
1-11
Harrell, T.M.
c97349b6-6f27-423d-b3d1-e35b30552692
Thomsen, O.T.
f3e60b22-a09f-4d58-90da-d58e37d68047
Dulieu-Barton, J.M.
9e35bebb-2185-4d16-a1bc-bb8f20e06632
Madsen, S.F.
fe2ab34a-8874-4047-a028-2cd4d0cc961e
Harrell, T.M.
c97349b6-6f27-423d-b3d1-e35b30552692
Thomsen, O.T.
f3e60b22-a09f-4d58-90da-d58e37d68047
Dulieu-Barton, J.M.
9e35bebb-2185-4d16-a1bc-bb8f20e06632
Madsen, S.F.
fe2ab34a-8874-4047-a028-2cd4d0cc961e

Harrell, T.M., Thomsen, O.T., Dulieu-Barton, J.M. and Madsen, S.F. (2019) Damage in CFRP composites subjected to simulated lighting strikes - Assessment of thermal and mechanical responses. Composites Part B: Engineering, 176, 1-11, [107298]. (doi:10.1016/j.compositesb.2019.107298).

Record type: Article

Abstract

Damage is inflicted upon Carbon Fiber Reinforced Polymer (CFRP) composite laminates using simulated lightning strikes to investigate the resulting residual mechanical properties. Seven different CFRP laminate specimens were exposed to simulated lightning strikes using three different electric waveforms. The three waveforms imposed were the 10/350 μs waveform, which simulates the first return stroke during a direct strike according to IEC 61400–24 Ed1.0. The second was a unipolar long stroke component, and the third was a combination of the first return stroke and the long stroke. After exposure to lightning, coupon specimens were prepared for mechanical testing. The test specimens were subsequently subjected to compression and shear loading to determine the post-strike mechanical properties. The compression tests were conducted using uniaxial coupons in accordance with ASTM standard D6641. The shear tests were conducted using V-notch specimens utilizing an Iosipescu test rig in accordance with ASTM standard D5379. Digital Image Correlation was used to capture the strain fields on the surface of the specimens. The results of the material coupon tests are compared with test results from pristine CFRP coupon samples that were not exposed to any electrical current. The shear and compression strengths, compressive and shear stress-strain curves, compressive and shear moduli, and the maximum temperature on the CFRP specimens during lightning tests are presented and discussed. Key results include that the largest reduction of strength occurred in the specimens that were subjected to the largest current and specific energy. The specific energy correlated more closely to the observed reduction of residual strength than the charge, and the damaged specimens displayed a higher degree of nonlinear stress-strain behavior than the pristine specimens.

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Journal paper #1_Harrell et al_v8_CompPartB_Accepted - Accepted Manuscript
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More information

Accepted/In Press date: 11 August 2019
e-pub ahead of print date: 28 August 2019
Published date: 1 November 2019
Keywords: CFRP composites, Lightning damage, Wind turbine blades, Compression and shear testing, Thermal imaging, Digital image correlation (DIC), Failure initiation stress

Identifiers

Local EPrints ID: 433475
URI: http://eprints.soton.ac.uk/id/eprint/433475
ISSN: 1359-8368
PURE UUID: c7d6bc9a-2064-45d9-a425-c0dc1b2f319f
ORCID for T.M. Harrell: ORCID iD orcid.org/0000-0002-0783-533X

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Date deposited: 23 Aug 2019 16:30
Last modified: 16 Mar 2024 08:08

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Contributors

Author: T.M. Harrell ORCID iD
Author: O.T. Thomsen
Author: S.F. Madsen

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