Clarifying the strain transfer between the host material with a crack opening displacement (COD) and the optical fiber after interfacial debonding remains a critical challenge for crack quantification. The interfacial debonding induced a triangular form strain profile around the crack due to the residual shear stresses at the interface. This study investigated the interfacial shear stress-slip relationship between the bare fiber and its coating layer through a plate splitting test. Based on that, we proposed an interfacial-fracture-energy-based analytical model to convert distributed fiber optic strains before and after interfacial debonding to CODs of micro- and macro-cracks. The accuracy of the model under a single crack was validated through plate splitting tests and the experimental data reported in the literature. Furthermore, experimental results from a four-point beam test were utilized to investigate the feasibility of the model under multiple cracks. The model, assisted by the strain superposition strategy, accurately quantified the CODs of multiple cracks before interfacial debonding but failed when interfacial debonding occurred. In addition, we proposed a simplified method based on the linear relationship between the debonded lengths and the corresponding CODs, which facilitates evaluation of the CODs after debonding.
BerrocalCGFernandezIRemplingR. The interplay between corrosion and cracks in reinforced concrete beams with non-uniform reinforcement corrosion. Mater Struct2022; 55(4): 120.
4.
ZhaoLTangFVerstryngeE, et al. Experimental and numerical investigation into corrosion-induced mortar/concrete cracking with distributed optical fiber sensors. J Civ Struct Health Monit2022; 12(4): 943–960.
5.
LinS-QTanD-YYinJ-H, et al. A novel approach to surface strain measurement for cylindrical rock specimens under uniaxial compression using distributed fibre optic sensor technology. Rock Mech Rock Eng2021; 54: 6605–6619.
6.
ZhangPYinZY. A novel deep learning-based modelling strategy from image of particles to mechanical properties for granular materials with CNN and BiLSTM. Comput Methods Appl Mech Eng2021; 382: 113858.
7.
XuJ-JTangC-SChengQ, et al. Monitoring and early detection of soil desiccation cracking using distributed fiber optical sensing. Géotechnique. Epub ahead of print 5July2022. DOI: 10.1680/jgeot.21.00397.
8.
LiH-JZhuH-HZhangC-X, et al. Monitoring flexure behavior of compacted clay beam using high-resolution distributed fiber optic strain sensors. Geotech Testing J2022; 45(3): 20200331.
9.
DomaneschiMNiccoliniGLacidognaG, et al. Nondestructive monitoring techniques for crack detection and localization in RC elements. Appl Sci2020; 10(9): 3248.
10.
OkabeYTanakaNTakedaN. Effect of fiber coating on crack detection in carbon fiber reinforced plastic composites using fiber Bragg grating sensors. Smart Mater Struct2002; 11(6): 892.
11.
ZhangSLiuHCoulibalyAAS, et al. Fiber optic sensing of concrete cracking and rebar deformation using several types of cable. Struct Control Health Monit2020; 28(2): e2664.
12.
GrunickeUHLienhartWVorwagnerA. Long-term monitoring of visually not inspectable tunnel linings using fibre optic sensing. Geomech Tunnell2021; 14(1): 19–32.
13.
YeXZhuH-HWangJ, et al. Subsurface multi-physical monitoring of a reservoir landslide with the fiber-optic nerve system. Geophys Res Lett2022; 49: e2022GL098211.
14.
WangDYZhuH-HWangJ, et al. Characterization of sliding surface deformation and stability evaluation of landslides with fiber–optic strain sensing nerves. Eng Geology2023; 314: 107011.
15.
ZhuH-HWangD-YShiB, et al. Performance monitoring of a curved shield tunnel during adjacent excavations using a fiber optic nervous sensing system. Tunn Undergr Space Technol2022; 124: 104483.
16.
AnsariFYuanL. Mechanics of bond and interface shear transfer in optical fiber sensors. J Eng Mech1998; 124(4): 385–394.
17.
LiD-SLi SrHRenL, et al. Strain transferring analysis of fiber Bragg grating sensors. Opt Eng2006; 45(2): 024402.
18.
LiH-NZhouG-DRenL, et al. Strain transfer coefficient analyses for embedded fiber Bragg grating sensors in different host materials. J Eng Mech2009; 135(12): 1343–1353.
19.
TanXBaoYZhangQ, et al. Strain transfer effect in distributed fiber optic sensors under an arbitrary field. Autom Constr2021; 124: 103597.
20.
ChapeleauXBassilA. A general solution to determine strain profile in the core of distributed fiber optic sensors under any arbitrary strain fields. Sensors2021; 21(16): 5423.
21.
ImaiMFengM. Sensing optical fiber installation study for crack identification using a stimulated Brillouin-based strain sensor. Struct Health Monit2012; 11(5): 501–509.
22.
FengXZhouJSunC, et al. Theoretical and experimental investigations into crack detection with BOTDR-distributed fiber optic sensors. J Eng Mech2013; 139(12): 1797–1807.
23.
BassilAChapeleauXLeducD, et al. Concrete crack monitoring using a novel strain transfer model for distributed fiber optics sensors. Sensors2020; 20(8): 2220.
24.
ZhangSLiuHChengJ, et al. A mechanical model to interpret distributed fiber optic strain measurement at displacement discontinuities. Struct Health Monit2020; 20(5): 2584–2603.
25.
BillonAHénaultJ-MQuiertantM, et al. Qualification of a distributed optical fiber sensor bonded to the surface of a concrete structure: a methodology to obtain quantitative strain measurements. Smart Mater Struct2015; 24(11): 115001.
26.
ZhaoLTangFLiH.-N, et al. Characterization of OFDR distributed optical fiber for crack monitoring considering fiber-coating interfacial slip. Struct Health Monit2022; 22(1): 180–200.
27.
YeHLiuJZhouY, et al. Crack detection and retardation of steel structure by smart CFRP embedding PPP-BOTDA fiber sensors. J Building Eng2022; 49: 104018.
28.
YeHLiuJZhouY, et al. Monitoring of crack opening displacement of steel structure by PPP-BOTDA-distributed fiber optical sensors: theory and experiment. Eng Fracture Mech2022; 262: 108275.
29.
WangCOlsonMDoijkhandN, et al. A novel DdTS technology based on fiber optics for early leak detection in pipelines. In 2016 IEEE international carnahan conference on security technology (ICCST), Orlando, FL, USA, 2016. IEEE.
30.
SieńkoRZychMBednarskiŁ, et al. Strain and crack analysis within concrete members using distributed fibre optic sensors. Struct Health Monit2019; 18(5–6): 1510–1526.
31.
BerrocalCGFernandezIRemplingR. Crack monitoring in reinforced concrete beams by distributed optical fiber sensors. Struct Infrastruct Eng2020; 17(1): 124–139.
32.
TanXAbu-ObeidahABaoY, et al. Measurement and visualization of strains and cracks in CFRP post-tensioned fiber reinforced concrete beams using distributed fiber optic sensors. Autom Constr2021; 124: 103604.
33.
FernandezIBerrocalCGAlmfeldtS, et al. Monitoring of new and existing stainless-steel reinforced concrete structures by clad distributed optical fibre sensing. Struct Health Monit2023; 22(1): 257–275.
34.
TanX.BaoY. Measuring crack width using a distributed fiber optic sensor based on optical frequency domain reflectometry. Measurement2021; 172, 108945.
35.
BassilA. Distributed fiber optics sensing for crack monitoring of concrete structures. Doctoral dissertation, Université de Nantes, 2019.
36.
TanXMahjoubiSZouX, et al. Metaheuristic inverse analysis on interfacial mechanics of distributed fiber optic sensors undergoing interfacial debonding. Mech Syst Signal Process2023; 200: 110532.
37.
ZhuH-HSheJ-KZhangC-C, et al. Experimental study on pullout performance of sensing optical fibers in compacted sand. Measurement2015; 73: 284–294.
38.
MengDAnsariFFengX. Detection and monitoring of surface micro-cracks by PPP-BOTDA. Appl Optics2015; 54(16): 4972–4978.
39.
DuckGLeblancM. Arbitrary strain transfer from a host to an embedded fiber-optic sensor. Smart Mater Struct2000; 9(4): 492.
40.
HerSCHuangCY. Effect of coating on the strain transfer of optical fiber sensors. Sensors2011; 11(7): 6926–6941.
41.
KimS-WJeongM-SLeeIKim, et al. Determination of the maximum strains experienced by composite structures using metal coated optical fiber sensors. Compos Sci Technol2013; 78: 48–55.
42.
FalcetelliFRossiLDi SanteR, et al. Strain transfer in surface-bonded optical fiber sensors. Sensors2020; 20(11): 3100.
43.
WanKTLeungCKOlsonNG. Investigation of the strain transfer for surface-attached optical fiber strain sensors. Smart Mater Struct2008, 17(3): 035037.
44.
ZhouHFernandoDToreroJL, et al. Bond behavior of CFRP-to-steel bonded joints at mild temperatures: experimental study. J Compos Constr2020; 24(6): 04020070.
45.
GuoDGaoWYLiuYL, et al. Intermediate crack-induced debonding in CFRP-retrofitted notched steel beams at different service temperatures: experimental test and finite element modeling. Compos Struct2023; 304: 116388.
46.
ZhengXShiBZhangC-C, et al. Strain transfer mechanism in surface-bonded distributed fiber-optic sensors subjected to linear strain gradients: theoretical modeling and experimental validation. Measurement2021; 179: 109510.
47.
HoHCChungKFLiuX, et al. Modelling tensile tests on high strength S690 steel materials undergoing large deformations. Eng Struct2019; 192: 305–322.
48.
HuYFChungKFJinH, et al. Structural behaviour of T-joints between high strength S690 steel cold-formed circular hollow sections. J Constr Steel Res2021; 182: 106686.
