Damage detection in adhesively bonded single lap joints by using backface strain: Proposing a new position for backface strain gauges

Sadeghi, M.Z.; Weiland, Josef; Preisler, Andreas; Zimmermann, J.; Schiebahn, Alexander; Reisgen, Uwe; Schroeder, K.U.

doi:10.1016/j.ijadhadh.2019.102494

Cited by 28 publications

(18 citation statements)

References 23 publications

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“…Instead of directly looking for defects, there are relatively more economical techniques suitable for real-time monitoring of the integrity degradation of adhesive joints. These include strain/stiffness monitoring using back face strain gages [21][22][23], resistance monitoring of adhesive joints made conductive by adding carbon nanotubes [24,25] and optical fiber sensors signal surveillance [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. Strain gages can only be applied to the outer surface, but they will disrupt an otherwise smooth surface and are susceptible to environmental degradation.…”

Section: Introductionmentioning

confidence: 99%

Adhesive Joint Integrity Monitoring Using the Full Spectral Response of Fiber Bragg Grating Sensors

Shin

Lin

2021

Polymers

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Although adhesive joining has many advantages over traditional joining techniques, their integrity is more difficult to examine and monitor. Serious structural failures might follow if adhesive joint degradation goes undetected. Available non-destructive examination (NDE) methods to detect defects are helpful in discovering defective joints during fabrication. For long-term monitoring of joint integrity, many of these NDE techniques are prohibitively expensive and time-consuming to carry out. Recently, fiber Bragg grating (FBG) sensors have been shown to be able to reflect strain in adhesive joints and offer an economical alternative for on-line monitoring. Most of the available works relied on the peak shifting phenomenon for sensing and studies on the use of full spectral responses for joint integrity monitoring are still lacking. Damage and disbonding inside an adhesive joint will give rise to non-uniform strain field that may chirp the FBG spectrum. It is reasoned that the full spectral responses may reveal the damage status inside the adhesive joints. In this work, FBGs are embedded in composite-to-composite single lap joints. Tensile and fatigue loading to joint failure have been applied, and the peak splitting and broadening of the full spectral responses from the embedded FBGs are shown to reflect the onset and development of damages. A parameter to quantify the change in the spectral responses has been proposed and independent assessment of the damage monitoring capability has been verified with post-damage fatigue tests.

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Section: Introductionmentioning

confidence: 99%

Adhesive Joint Integrity Monitoring Using the Full Spectral Response of Fiber Bragg Grating Sensors

Shin

Lin

2021

Polymers

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“…Lee et al [6] used a surface strain gauge technique to measure the strain of SLJs and found that there was a linear relationship between surface strain and load. Sadeghi et al [7] proposed a location for positioning the back-face strain gauge on the adhesively bonded SLJs for damage detection. Moroni et al [8] selected different pre-treatments to be applied over aluminum and stainless steel adherents' surfaces and provided the state of the surface morphology of SLJs.…”

Section: Doi: 101002/mats202000066mentioning

confidence: 99%

“…Sadeghi et al. [ 7 ] proposed a location for positioning the back‐face strain gauge on the adhesively bonded SLJs for damage detection. Moroni et al.…”

Section: Introductionmentioning

confidence: 99%

Finite Element Analysis of Stress Wave Propagation in Adhesive Joints under Low Speed Impact Tensile Loadings

2020

Macro Theory & Simulations

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“…Local moisture content can be monitored by embedded interdigital electrode sensor that made use of impedance changes [ 46 ] and optical fiber evanescent sensor that depended on light energy loss with surrounding refractive index changes [ 47 , 48 ]. Computational methods have been developed to predict the diffusion of moisture and the swelling strain under known boundary conditions [ 13 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ]. The calculated moisture contents agreed well with the gravimetrically measured ones [ 13 , 43 , 44 ].…”

Section: Introductionmentioning

confidence: 99%

“…Instead of monitoring moisture content or directly looking for defects, there are techniques suitable for real time monitoring of the integrity degradation of adhesive joints. These include strain/stiffness monitoring using back face strain gages [ 49 , 50 , 51 ], resistance monitoring of adhesive joints that were made conductive by adding carbon nanotubes [ 52 , 53 ] and optical fiber sensors signal surveillance [ 43 , 44 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 ]. Strain gages can only be applied to the outer surface, they will disrupt an otherwise smooth surface and are susceptible to environmental degradation.…”

Section: Introductionmentioning

confidence: 99%

Hygrothermal Damage Monitoring of Composite Adhesive Joint Using the Full Spectral Response of Fiber Bragg Grating Sensors

Shin

Lin

2022

Polymers

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Adhesive joints in composite structures are subject to degradation by elevated temperature and moisture. Moisture absorption leads to swelling, plasticization, weakening of the interface, interfacial defects/cracking and reduction in strength. Moisture and material degradation before the formation of defects are not readily revealed by conventional non-destructive examination techniques. Embedded fiber Bragg grating (FBG) sensors can reflect the swelling strain in adhesive joints and offer an economical alternative for on-line monitoring of moisture absorption under hygrothermal aging. Most of the available works relied on the peak shifting phenomenon for sensing. Degradation of adhesive and interfacial defects will lead to non-uniform strain that may chirp the FBG spectrum, causing complications in the peak shifting measurement. It is reasoned that the full spectral responses may be more revealing regarding the joint’s integrity. Studies on this aspect are still lacking. In this work, single-lap joint composite specimens with embedded FBGs are soaked in 60 °C water for 30 days. Spectrum evolution during this period and subsequent tensile and fatigue failure has been studied to shed some light on the possible use of the full spectral response to monitor the development of hygrothermal degradation.

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Damage detection in adhesively bonded single lap joints by using backface strain: Proposing a new position for backface strain gauges

Cited by 28 publications

References 23 publications

Adhesive Joint Integrity Monitoring Using the Full Spectral Response of Fiber Bragg Grating Sensors

Adhesive Joint Integrity Monitoring Using the Full Spectral Response of Fiber Bragg Grating Sensors

Finite Element Analysis of Stress Wave Propagation in Adhesive Joints under Low Speed Impact Tensile Loadings

Hygrothermal Damage Monitoring of Composite Adhesive Joint Using the Full Spectral Response of Fiber Bragg Grating Sensors

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