PSI - Issue 52

Available online at www.sciencedirect.com Available online at www.sciencedirect.com Available online at www.sciencedirect.com

ScienceDirect Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2023) 000–000 Procedia Structural Integrity 52 (2024) 709–718 Structural Integrity Procedia 00 (2023) 000–000

www.elsevier.com / locate / procedia www.elsevier.com / locate / procedia

© 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of Professor Ferri Aliabadi Abstract This research presents a comprehensive investigation into the measurement consistency of distributed fiber optic sensing in compos ite structures under diverse test scenarios. The study encompasses fifty-six independent experiments, categorized into six groups, comprising tensile, fatigue, three-point bending, and three sets of temperature experiments. The strain-frequency shift coe ffi cient and temperature-frequency shift coe ffi cient of distributed fiber optic sensing based on Optical Frequency Domain Reflectometry in di ff erent test scenarios are visually represented using Cumming plots, and their normality is rigorously assessed utilizing the Kolmogorov-Smirnov test. Furthermore, the coe ffi cients’ consistency is evaluated through Cronbach’s alpha, McDonald’s omega, and Split-half reliability, predicated on the confirmed normal distribution conclusion. The results demonstrate that the strain frequency shift coe ffi cient consistently remains around -6.4 µε/ GHz across diverse tests, while being subject to ambient temper ature variations. The temperature-frequency shift coe ffi cient is notably influenced by the coating material and installation state of single mode fiber sensors, with recorded values of -1.55 ◦ C / GHz (acrylate coating, free state), -1.04 ◦ C / GHz (acrylate coating, surface mounted), and -1.28 ◦ C / GHz (polymer coating, free state), respectively. Remarkably, both strain-frequency shift coe ffi cient and temperature-frequency shift coe ffi cient exhibit high consistency across the entire range of test scenarios. In addition, the standard uncertainty (type A) of frequency shift measurements across the fifty-six independent test scenarios consistently remains below 0.1 GHz, a ffi rming the robustness and reliability of distributed fiber optic sensing for strain and temperature data acquisition in composite structures. These findings underscore the capability of distributed fiber optic sensing in accurately characterizing composite materials under varying environmental conditions and loading. Keywords: Structural Health Monitoring; distributed fiber optical sensing;Optical Frequency Domain Reflectometry; measurement consistency; composite structures. Abstract This research presents a comprehensive investigation into the measurement consistency of distributed fiber optic sensing in compos ite structures under diverse test scenarios. The study encompasses fifty-six independent experiments, categorized into six groups, comprising tensile, fatigue, three-point bending, and three sets of temperature experiments. The strain-frequency shift coe ffi cient and temperature-frequency shift coe ffi cient of distributed fiber optic sensing based on Optical Frequency Domain Reflectometry in di ff erent test scenarios are visually represented using Cumming plots, and their normality is rigorously assessed utilizing the Kolmogorov-Smirnov test. Furthermore, the coe ffi cients’ consistency is evaluated through Cronbach’s alpha, McDonald’s omega, and Split-half reliability, predicated on the confirmed normal distribution conclusion. The results demonstrate that the strain frequency shift coe ffi cient consistently remains around -6.4 µε/ GHz across diverse tests, while being subject to ambient temper ature variations. The temperature-frequency shift coe ffi cient is notably influenced by the coating material and installation state of single mode fiber sensors, with recorded values of -1.55 ◦ C / GHz (acrylate coating, free state), -1.04 ◦ C / GHz (acrylate coating, surface mounted), and -1.28 ◦ C / GHz (polymer coating, free state), respectively. Remarkably, both strain-frequency shift coe ffi cient and temperature-frequency shift coe ffi cient exhibit high consistency across the entire range of test scenarios. In addition, the standard uncertainty (type A) of frequency shift measurements across the fifty-six independent test scenarios consistently remains below 0.1 GHz, a ffi rming the robustness and reliability of distributed fiber optic sensing for strain and temperature data acquisition in composite structures. These findings underscore the capability of distributed fiber optic sensing in accurately characterizing composite materials under varying environmental conditions and loading. Keywords: Structural Health Monitoring; distributed fiber optical sensing;Optical Frequency Domain Reflectometry; measurement consistency; composite structures. Abstract This research presents a comprehensive investigation into the measurement consistency of distributed fiber optic sensing in compos ite structures under diverse test scenarios. The study encompasses fifty-six independent experiments, categorized into six groups, comprising tensile, fatigue, three-point bending, and three sets of temperature experiments. The strain-frequency shift coe ffi cient and temperature-frequency shift coe ffi cient of distributed fiber optic sensing based on Optical Frequency Domain Reflectometry in di ff erent test scenarios are visually represented using Cumming plots, and their normality is rigorously assessed utilizing the Kolmogorov-Smirnov test. Furthermore, the coe ffi cients’ consistency is evaluated through Cronbach’s alpha, McDonald’s omega, and Split-half reliability, predicated on the confirmed normal distribution conclusion. The results demonstrate that the strain frequency shift coe ffi cient consistently remains around -6.4 µε/ GHz across diverse tests, while being subject to ambient temper ature variations. The temperature-frequency shift coe ffi cient is notably influenced by the coating material and installation state of single mode fiber sensors, with recorded values of -1.55 ◦ C / GHz (acrylate coating, free state), -1.04 ◦ C / GHz (acrylate coating, surface mounted), and -1.28 ◦ C / GHz (polymer coating, free state), respectively. Remarkably, both strain-frequency shift coe ffi cient and temperature-frequency shift coe ffi cient exhibit high consistency across the entire range of test scenarios. In addition, the standard uncertainty (type A) of frequency shift measurements across the fifty-six independent test scenarios consistently remains below 0.1 GHz, a ffi rming the robustness and reliability of distributed fiber optic sensing for strain and temperature data acquisition in composite structures. These findings underscore the capability of distributed fiber optic sensing in accurately characterizing composite materials under varying environmental conditions and loading. Keywords: Structural Health Monitoring; distributed fiber optical sensing;Optical Frequency Domain Reflectometry; measurement consistency; composite structures. Fracture, Damage and Structural Health Monitoring Strain measurement consistency of distributed fiber optic sensors for monitoring composite structures under various loading www.elsevier.com / locate / procedia Fracture, Damage and Structural Health Monitoring Strain measurement consistency of distributed fiber optic sensors for monitoring composite structures under various loading Fracture, Damage and Structural Health Monitoring Strain measurement consistency of distributed fiber optic sensors for monitoring composite structures under various loading YingwuLi a, ∗ , Zahra Sharif Khodaei a a Imperial College London,London, SW7 2BX, United Kingdom YingwuLi a, ∗ , Zahra Sharif Khodaei a a Imperial College London,London, SW7 2BX, United Kingdom YingwuLi a, ∗ , Zahra Sharif Khodaei a a Imperial College London,London, SW7 2BX, United Kingdom Carbon fiber reinforced polymer (CFRP) is a highly promising material known for its remarkable combination of high strength and light weight. Over the past few decades, it has found extensive application in the aeronautics industry, playing a significant role in advancing aviation aircraft Zhang et al. (2018). However, despite its exceptional properties, CFRP is susceptible to complex failure and damage mechanisms, leading to considerable maintenance costs Goossens et al. (2021). 1. Introduction Carbon fiber reinforced polymer (CFRP) is a highly promising material known for its remarkable combination of high strength and light weight. Over the past few decades, it has found extensive application in the aeronautics industry, playing a significant role in advancing aviation aircraft Zhang et al. (2018). However, despite its exceptional properties, CFRP is susceptible to complex failure and damage mechanisms, leading to considerable maintenance costs Goossens et al. (2021). Carbon fiber reinforced polymer (CFRP) is a highly promising material known for its remarkable combination of high strength and light weight. Over the past few decades, it has found extensive application in the aeronautics industry, playing a significant role in advancing aviation aircraft Zhang et al. (2018). However, despite its exceptional properties, CFRP is susceptible to complex failure and damage mechanisms, leading to considerable maintenance costs Goossens et al. (2021). ∗ Corresponding author. Tel.: + 4407548386524. E-mail address: yingwu.li19@imperial.ac.uk Structural Integrity Procedia 00 (2023) 000–000 1. Introduction 1. Introduction

∗ Corresponding author. Tel.: + 4407548386524. E-mail address: yingwu.li19@imperial.ac.uk

2452-3216 © 2023 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of Professor Ferri Aliabadi 10.1016/j.prostr.2023.12.071 2210-7843 © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of Professor Ferri Aliabadi. ∗ Corresponding author. Tel.: + 4407548386524. E-mail address: yingwu.li19@imperial.ac.uk 2210-7843 © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of Professor Ferri Aliabadi. 2210-7843 © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of Professor Ferri Aliabadi.