Thermal isolation of FBG optical fibre sensors for composite cure monitoring

Boateng, E.K.G.; Schubel, Peter; Umer, Rehan

doi:10.1016/j.sna.2019.01.001

Cited by 15 publications

(10 citation statements)

References 35 publications

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“…However, during the SMPC fabrication process, the LDPE tubes were slightly inserted into the SMPC specimens. Because of the protective cover and air gap between the DOFS and inner surface of the LDPE tube the temperature sensitivity of the DOFS might have been affected 39 . Filling a thermally conductive gel into the LDPE tube can enhance the temperature sensitivity of the protected areas of the DOFS 40 .…”

Section: Resultsmentioning

confidence: 99%

“…Because of the protective cover and air gap between the DOFS and inner surface of the LDPE tube the temperature sensitivity of the DOFS might have been affected. 39 Filling a thermally conductive gel into the LDPE tube can enhance the temperature sensitivity of the protected areas of the DOFS. 40 However, in this study the LDPE embedded regions were located at the outer edges of the SMPC specimens that are insignificant in analyzing the shape memory effect of the test specimens.…”

Section: Real-time Thermomechanical Behaviormentioning

confidence: 99%

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Distributed sensing based real‐time process monitoring of shape memory polymer components

Herath

Emmanuel

Jeewantha

et al. 2022

J of Applied Polymer Sci

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Shape memory polymer (SMP) materials have the capacity to undergo large deformations imposed by mechanical loading, hold a temporary shape, and then recover their original shape upon exposure to a particular external stimulus. The fiber reinforced shape memory polymer composites (SMPCs) with enhanced structural performances give a boost to breakthrough technologies for large-scale engineering applications. This article presents a novel technique for distributed optical fiber sensor (DOFS) embedded SMPCs intended for realtime process monitoring of large-scale engineering applications such as deployable space structures. Herein a carbon fiber reinforced SMPC was tested under a three-point flexural shape memory process and the DOFS data were acquired through optical backscatter reflectometry. Experiments were conducted in a temperature controlled thermal chamber coupled with a 10 kN electromechanical testing system. DOFSs offered unique advantages for spatially distributed dynamic temperature and strain measurements during the shape memory process. Compared to the standard test method dynamic mechanical analysis, larger samples can be tested effectively by using a single DOFS with large strain levels and shape complexity. The proposed technique demonstrated the ability of embedded DOFSs for in-situ shape memory characterization such as shape fixity ratio, shape recovery ratio and recovery rate. This technique will eliminate the challenges hindering the process monitoring and performance evaluation of large SMPC components operating in their real working environments.

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Section: Resultsmentioning

confidence: 99%

Section: Real-time Thermomechanical Behaviormentioning

confidence: 99%

Distributed sensing based real‐time process monitoring of shape memory polymer components

Herath

Emmanuel

Jeewantha

et al. 2022

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…Therefore, when using an FBG sensor to measure the residual strain of resin after curing, these temperature effects must be corrected. To measure the resin shrinkage during thermoforming, Boateng [ 25 ] designed different insulation envelopes to envelope the FBG sensor and insulate heat, ensuring that the FBG sensor would only detect the shrinkage of the resin. The design of the insulation envelopes could also be used in the measurement of heterogeneous residual strain; Huang [ 26 ] successfully used FBG and insulation envelopes to monitor the residual strain of a heterogeneous bonding structure.…”

Section: Introductionmentioning

confidence: 99%

Using a Fiber Bragg Grating Sensor to Measure Residual Strain in the Vacuum-Assisted Resin Transfer Molding Process

2022

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Vinyl ester (VE) resin has strong environmental tolerance and is the matrix commonly used in the composite materials of fiber-reinforced plastics (FRP). VE resin is often combined with glass fiber in different maritime structures, such as wind turbine blades, spinner cases, and nacelle cases. However, VE resin exhibits exothermic reactions and shrinkage during curing, which often generates residual strain in large structures and those with a high stacking number. This study explored the exothermic reaction and shrinkage of VE resin and glass fiber during the vacuum-assisted resin transfer molding process, as measured using a fiber Bragg grating sensor. The experiment results verified the relationship between the stacking number and residual strain shrinkage. In addition, the symmetric laminate method was used to prevent the bending–twisting coupling effect and subsequent warping deformation of the FRP laminated plate during curing. The experiment results also verified that the bottom layers of the FRP laminated plates produced using VE resin were closer to the mold, and exhibited more shrinkage as the stacking number increased. In addition, this study discovered that during the experiment, the symmetry layer of the FRP laminated plate had a higher exothermic temperature than the bottom layer as a result of the symmetry layer’s ineffective heat dissipation. Therefore, the curing shrinkage of the symmetry layer resin was measured. The experiment results indicated that if the stacking number was between 10 and 30, the residual strain shrinkage of the symmetry layer was greater than that of the surface layer. However, because of the symmetric laminate, the residual strain of the symmetry layer did not increase when the temperature increased. Therefore, the greatest residual strain occurred at the surface of the bottom layer of the laminated plate with a stacking number of 40.

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“…Therefore, in order to improve the durability and installation property of FBG, it is necessary to be encapsulated to reduce the erosion of the external environment of the fiber, such as ultraviolet and water vapor. The common encapsulation method of FBG sensors includes tube-encapsulated [10][11][12], fiber-reinforced polymer-encapsulated [13][14][15][16] and metal sheet-encapsulated methods [17,18].…”

Section: Introductionmentioning

confidence: 99%

Study of a Long-Gauge FBG Strain Sensor with Enhanced Sensitivity and Its Application in Structural Monitoring

Yang

Yang³

2021

Sensors

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A long-gauge fiber Bragg grating (FBG) strain sensor with enhanced strain sensitivity is proposed, which is encapsulated with two T-shaped metal blocks. Its fabrication method is described briefly, and the strain sensitivity can be flexibly adjusted through changing its packaging method. A series of experiments are carried out to study the packaging and its sensing properties. The experimental results show that the strain and temperature sensitivity coefficient of the sensor are three times larger than the common FBG sensors. The linearity coefficients of the FBG sensor are larger than 0.999, and the relative error of the repeatability of all sensor samples is less than 1%. Through the stability test on the actual bridge, it is revealed that the long-term stability of the sensor is excellent, and the maximum error is less than 1.5%. In addition, the proposed FBG strain sensors are used to conduct a shear strengthening experiment on a reinforced concrete (RC) beam to verify its working performance. The experimental results show that the strain change and crack propagation of the RC beam are well monitored by the sensors during the loading process.

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Thermal isolation of FBG optical fibre sensors for composite cure monitoring

Cited by 15 publications

References 35 publications

Distributed sensing based real‐time process monitoring of shape memory polymer components

Distributed sensing based real‐time process monitoring of shape memory polymer components

Using a Fiber Bragg Grating Sensor to Measure Residual Strain in the Vacuum-Assisted Resin Transfer Molding Process

Study of a Long-Gauge FBG Strain Sensor with Enhanced Sensitivity and Its Application in Structural Monitoring

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