Polyimide-coated fiber Bragg grating sensor for monitoring of the composite materials curing process

Abstract

In this paper, a polyimide-coated fiber Bragg grating sensor for temperature and strain monitoring of the composite materials curing process in real time is proposed. New experiments have been done in much the same way as earlier, with the changes and peculiarities as follows: we demonstrate what we believe to be a new grating polyimide-coated fiber Bragg grating. It can resist 300°C and the grating in the earlier paper can resist only 130°C. In this paper we measure temperature and strain at the same time. In addition, we analyze the relative difference in this paper. The temperature and strain are calculated according to the central wavelength. To compare the temperature results, a thermocouple is used to monitor the temperature simultaneously. For comparing the strain results, a strain gauge is used to monitor the strain simultaneously. The maximum relative difference of temperature between the results obtained by a polyimide-coated fiber Bragg grating sensor and the results obtained by a thermocouple is 2.5%. The maximum relative difference of strain between the results obtained by a polyimide-coated fiber Bragg grating sensor and the results obtained by a strain gauge is 0.2%. Additionally, a new signal demodulation scheme for experimental data processing is used to improve the accuracy of the monitoring results. The experimental results have good repeatability. The research results provide important references for optimization of the curing process and improvement of the technological process of the composite materials curing process.