The creep behavior of composite wing leading edges resulting from nonequilibrium residual stresses and material viscoelasticity needs to be evaluated comprehensively as it significantly affects assembly. In this study, long-term creep monitoring of a composite wing leading edge used in an actual airplane for 710 h is conducted using embedded fiber Bragg grating arrays and a creep extraction algorithm. The spectra and Bragg wavelength shifts of two embedded arrays, which involve temperature, thermal expansion, and creep, are recorded and analyzed. The creep curve of the composite wing leading edge is reconstructed and further predicted using the creep extraction algorithm based on multiparameter decoupling and the Burgers model. This study elucidates the enlargement of the opening size in the composite wing leading edge by measuring the tensile strain above the neutral axis. The predicted creep time serves as a valuable reference for determining the appropriate assembly timing.
BerendsHvan BurgEvan RaaijEM.Contacts and contracts: cross-level network dynamics in the development of an aircraft material. Organ Sci2011; 22: 940–960.
2.
MarshG.Airframers exploit composites in battle for supremacy. Reinf Plast2005; 49: 26–32.
3.
HwangJHJinCKLeeMS, et al. Effect of surface roughness on the bonding strength and spring-back of a CFRP/CR980 hybrid composite. Metals (Basel)2018; 8: 1–12.
4.
YoungSWonKChoiJ, et al. Spring-back characteristics of fiber metal laminate (GLARE) in brake forming process. Int J Adv Manuf Technol2007; 32: 445–451.
5.
ParsaMHNasherSEttehadM.Experimental and finite element study on the spring back of double curved aluminum/polypropylene/aluminum sandwich sheet. Mater Des2010; 31: 4174–4183.
6.
TakagakiKMinakuchiSTakedaN.Process-induced strain and distortion in curved composites. Part I: development of fiber-optic strain monitoring technique and analytical methods. Compos A Appl Sci Manuf2017; 103: 236–251.
7.
LeeHSSunYKimC, et al. Characterization of linear viscoelastic behavior of epoxy molding compound subjected to uniaxial compression and hydrostatic pressure. IEEE Trans Compon Packag Manuf Technol2018; 8: 1363–1372.
8.
RenHTHuANZhaoGF.Experimental study of creep behavior of carbon fiber reinforced plastics. Gongcheng Lixue/Eng Mech2004; 21: 10–14.
9.
PedrazzoliDDorigatoAPegorettiA.Monitoring the mechanical behavior under ramp and creep conditions of electrically conductive polymer composites. Compos A Appl Sci Manuf2012; 43: 1285–1292.
10.
ZhangYYSunZLiYQ, et al. Tensile creep behavior of short-carbon-fiber reinforced polyetherimide composites. Compos B Eng2021; 212: 108717.
11.
GoertzenWKKesslerMR.Creep behavior of carbon fiber/epoxy matrix composites. Mater Sci Eng A2006; 421: 217–225.
12.
MajdaPSkrodzewiczJ.A modified creep model of epoxy adhesive at ambient temperature. Int J Adhes Adhes2009; 29: 396–404.
13.
TsukadaTTakedaSIMinakuchiS, et al. Evaluation of the influence of cooling rate on residual strain development in unidirectional carbon fibre/polyphenylenesulfide laminates using embedded fibre Bragg grating sensors. J Compos Mater2017; 51: 1849–1859.
14.
TsukadaTMinakuchiSTakedaN.Identification of process-induced residual stress/strain distribution in thick thermoplastic composites based on in situ strain monitoring using optical fiber sensors. J Compos Mater2019; 53: 3445–3458.
15.
ChenCWuQXiongK, et al. Hybrid temperature and stress monitoring of woven fabric thermoplastic composite using fiber bragg grating based sensing technique. Sensors (Switzerland)2020; 20: 1–16.
16.
TakedaSITsukadaTMinakuchiS, et al. Fiber-optic sensing for press forming of L-shaped thermoplastic composites. Procedia Eng2017; 188: 348–353.
17.
HiranoYMizutaniTIwahoriY, et al. An investigation on spring-in behavior of Va-RTM composite wing structure. In: 16th international conference on composite materials, Kyoto, Japan, 8–13 July 2007, paper no. TuJA2-01ge_hiranoy224878p.
18.
DingAFangSLiX, et al. Experimental and numerical investigation of tool-part interaction on the process-induced distortions in composite structures. Compos Struct2022; 279: 114871.
19.
MinakuchiSUmeharaTTakagakiK, et al. Life cycle monitoring and advanced quality assurance of L-shaped composite corner part using embedded fiber-optic sensor. Compos A Appl Sci Manuf2013; 48: 153–161.
20.
LengJAsundiA.Structural health monitoring of smart composite materials by using EFPI and FBG sensors. Sensors Actuat A Phys2003; 103: 330–340.
21.
NielsenMWSchmidtJWHøghJH, et al. Life cycle strain monitoring in glass fibre reinforced polymer laminates using embedded fibre Bragg grating sensors from manufacturing to failure. J Compos Mater2014; 48: 365–381.
22.
TakedaSKoyanagiJUtsunomiyaS, et al. Long-term monitoring of strain changes in CFRP using FBG sensors. In: 18th international conference on composite materials, Jeju Island, South Korea, 21–26 August 2011, paper no. Th06-4-AF0976.
23.
LiGHongCDaiJ, et al. FBG-based creep analysis of GFRP materials embedded in concrete. Math Probl Eng2013; 2013: 631216.
24.
ZhangBShangS.Experimental study on long-term creep preference of flexural members strengthened with prestressed CFRP plate. AIP Conf Proc2017; 1864: 020225.
25.
CastilleroJArangurenGEtxanizJ, et al. Composite leading edge monitoring with a guided wave system. In: RizzoPMilazzoA (eds.) European workshop on structural health monitoring: special collection of 2020 papers-volume 1. Berlin, Germany: Springer Nature, 2021, pp. 830–837.
26.
ParkCYJangBWKimJH, et al. Bird strike event monitoring in a composite UAV wing using high speed optical fiber sensing system. Compos Sci and Technol2012; 72(4): 498–505.
27.
JayJA.An overview of macrobending and microbending of optical fibers. White Pap Corning2010; 12: 1–21.
28.
DingALiSWangJ, et al. A three-dimensional thermo-viscoelastic analysis of process-induced residual stress in composite laminates. Compos Struct2015; 129: 60–69.
29.
HudsonTB. Real-time cure monitoring of composites using a guided wave-based system with high temperature piezoelectric transducers, fiber Bragg gratings, and phase-shifted fiber Bragg gratings. Raleigh, NC: North Carolina State University.
30.
RothsJWilfertAKratzerP, et al. Strain calibration of optical FBG-based strain sensors. In: Fourth European workshop on optical fibre sensors, Porto, Portugal, 8 September 2010, paper no. 76530F.
31.
ChenCWuQXiongK, et al. Data-processing-aided temperature monitoring of composite forming process using unannealed fiber Bragg grating. In: Eighth symposium on novel photoelectronic detection technology and applications, Kunming, China, 29 March 2022, paper no. 121692U.
RajabzadehAHeusdensRHendriksRC, et al. Calculation of the mean strain of smooth non-uniform strain fields using conventional FBG sensors. J Light Technol2018; 36: 3716–3725.
34.
HörbergEÅkermoMHallströmS.Moisture effect on shape distortions of curved quasi-isotropic prepreg composite laminates. Compos A Appl Sci Manuf2021; 145: 106361.
35.
AscioneLBerardiVPD’AponteA.Creep phenomena in FRP materials. Mech Res Commun2012; 43: 15–21.
