Decoupling the Effects of Temperature, Strain, and Refractive Index in Long-Period Fiber Grating Used for Epoxy Resin Cure Monitoring
Epoxy resins are widely used in the manufacture of composite materials for a wide range of applications. Control of the curing process is an important consideration in ensuring product quality and minimizing production times. The curing of epoxy resin is associated with temperature, strain, and refr...
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MDPI AG
2025-01-01
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| author | Oleg V. Ivanov Kaushal Bhavsar James M. Gilbert |
| author_facet | Oleg V. Ivanov Kaushal Bhavsar James M. Gilbert |
| author_sort | Oleg V. Ivanov |
| collection | DOAJ |
| description | Epoxy resins are widely used in the manufacture of composite materials for a wide range of applications. Control of the curing process is an important consideration in ensuring product quality and minimizing production times. The curing of epoxy resin is associated with temperature, strain, and refractive index changes but it is difficult to monitor these quantities individually and hence difficult to achieve accurate control of the curing process. One promising approach for monitoring these quantities is the use of long-period fiber gratings (LPFG). We analyze the spectral response of a LPFG in epoxy resins to temperature, strain, and refractive index. Wavelength shifts and dip amplitudes of cladding mode notches are monitored and are used to decouple temperature, strain, and refractive index for gratings in air, liquid, and hardened resins. The three measurands are found from wavelength shifts and dip amplitudes, employing multiplication by a weighted pseudo-inverse matrix assuming linear dependences between the spectral and external parameters. We propose a new model to describe the influence of fiber parameters and external refractive index, temperature, and strain on the spectral behavior of long-period fiber gratings in epoxy resins during hardening. The results obtained can be utilized for multiparameter cure process monitoring of epoxy resins by using long-period fiber gratings. |
| format | Article |
| id | doaj-art-f10b2c935d464c46ac5248c5b6f51a91 |
| institution | DOAJ |
| issn | 1424-8220 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | MDPI AG |
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| series | Sensors |
| spelling | doaj-art-f10b2c935d464c46ac5248c5b6f51a912025-08-20T02:48:10ZengMDPI AGSensors1424-82202025-01-0125378610.3390/s25030786Decoupling the Effects of Temperature, Strain, and Refractive Index in Long-Period Fiber Grating Used for Epoxy Resin Cure MonitoringOleg V. Ivanov0Kaushal Bhavsar1James M. Gilbert2School of Engineering, University of Hull, Hull HU6 7RX, UKSchool of Engineering, University of Hull, Hull HU6 7RX, UKSchool of Engineering, University of Hull, Hull HU6 7RX, UKEpoxy resins are widely used in the manufacture of composite materials for a wide range of applications. Control of the curing process is an important consideration in ensuring product quality and minimizing production times. The curing of epoxy resin is associated with temperature, strain, and refractive index changes but it is difficult to monitor these quantities individually and hence difficult to achieve accurate control of the curing process. One promising approach for monitoring these quantities is the use of long-period fiber gratings (LPFG). We analyze the spectral response of a LPFG in epoxy resins to temperature, strain, and refractive index. Wavelength shifts and dip amplitudes of cladding mode notches are monitored and are used to decouple temperature, strain, and refractive index for gratings in air, liquid, and hardened resins. The three measurands are found from wavelength shifts and dip amplitudes, employing multiplication by a weighted pseudo-inverse matrix assuming linear dependences between the spectral and external parameters. We propose a new model to describe the influence of fiber parameters and external refractive index, temperature, and strain on the spectral behavior of long-period fiber gratings in epoxy resins during hardening. The results obtained can be utilized for multiparameter cure process monitoring of epoxy resins by using long-period fiber gratings.https://www.mdpi.com/1424-8220/25/3/786long-period fiber gratingepoxy resincure monitoringrefractive index sensing |
| spellingShingle | Oleg V. Ivanov Kaushal Bhavsar James M. Gilbert Decoupling the Effects of Temperature, Strain, and Refractive Index in Long-Period Fiber Grating Used for Epoxy Resin Cure Monitoring Sensors long-period fiber grating epoxy resin cure monitoring refractive index sensing |
| title | Decoupling the Effects of Temperature, Strain, and Refractive Index in Long-Period Fiber Grating Used for Epoxy Resin Cure Monitoring |
| title_full | Decoupling the Effects of Temperature, Strain, and Refractive Index in Long-Period Fiber Grating Used for Epoxy Resin Cure Monitoring |
| title_fullStr | Decoupling the Effects of Temperature, Strain, and Refractive Index in Long-Period Fiber Grating Used for Epoxy Resin Cure Monitoring |
| title_full_unstemmed | Decoupling the Effects of Temperature, Strain, and Refractive Index in Long-Period Fiber Grating Used for Epoxy Resin Cure Monitoring |
| title_short | Decoupling the Effects of Temperature, Strain, and Refractive Index in Long-Period Fiber Grating Used for Epoxy Resin Cure Monitoring |
| title_sort | decoupling the effects of temperature strain and refractive index in long period fiber grating used for epoxy resin cure monitoring |
| topic | long-period fiber grating epoxy resin cure monitoring refractive index sensing |
| url | https://www.mdpi.com/1424-8220/25/3/786 |
| work_keys_str_mv | AT olegvivanov decouplingtheeffectsoftemperaturestrainandrefractiveindexinlongperiodfibergratingusedforepoxyresincuremonitoring AT kaushalbhavsar decouplingtheeffectsoftemperaturestrainandrefractiveindexinlongperiodfibergratingusedforepoxyresincuremonitoring AT jamesmgilbert decouplingtheeffectsoftemperaturestrainandrefractiveindexinlongperiodfibergratingusedforepoxyresincuremonitoring |