Abstract
Carbon fiber reinforced plastics (CFRP) have many mechanical properties that are superior to those of conventional structural materials and are becoming more and more widely used. Monitoring the curing process used to produce such composite material is important to ensure the quality of the process, especially for the characterization of residual strains after the material has been manufactured. In this study, we present a tilted fiber Bragg grating (TFBG) sensor used to monitor the curing of CFRP composite materials. The TFBG sensor was embedded into the layers of CFRP laminates to study the curing residual strain of the laminates. The experimental results showed that the curing residual stress was about −22.25 MPa, the axial residual strain was −281.351 με, and lateral residual strain of 89.91 με. The TFBG sensor was found to be sensitive to the curing residual strain of the CFRP, meaning that it has potential for use in applications involving composite curing processes. Moreover, it is indeed possible to improve the properties of composite materials via the optimization and monitoring of their curing parameters.
Highlights
Carbon fiber reinforced polymers (CFRPs) have been widely used as structural materials in the aerospace and engineering industries in recent years as they are lightweight, strong in terms of specific strength, and resistant to acids, alkali corrosion, and fatigue load [1,2,3]
The most commonly used of these techniques is differential scanning calorimetry (DSC), which is used primarily to calculate the amount of heat stored in a material as it heats up as well as the heat absorbed or released during chemical reactions or phase changes that the difference in the amount of heat required to increase the temperature of a sample and reference
We present a new method that employs a tilted fiber Bragg grating (TFBG) sensor for the real-time monitoring of the curing process quality and the analysis of curing internal residual strains of CFRP
Summary
Carbon fiber reinforced polymers (CFRPs) have been widely used as structural materials in the aerospace and engineering industries in recent years as they are lightweight, strong in terms of specific strength, and resistant to acids, alkali corrosion, and fatigue load [1,2,3]. A TFBG sensor was embedded into the lamina of composite materials, after which the curing development as well as internal residual strain values during the curing process were measured. Bragg mode and cladding mode resonance, we observed a differential evolution that was attributable to a surrounding refractive index (SRI) modification due to the polymerization of the CFRP. In this case, if there is a residual strain applied on the sensor during the curing, this strain will affect the Bragg peak shape, which is directly observed in the spectrum. The wavelength shifts occur due to variations in temperature (ΔT), strain (ε) and/or the surrounding refractive index (ΔSRI).
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