Monitoring of Internal Stress in Stainless Steel Materials at High Temperatures Using Optical FPI and LPFG

With the development of modern industrial, the requirements for the performance of stainless steel materials are increasingly stringent, especially in high-temperature environments such as aerospace and nuclear power plants. However, in practical applications, stainless steel materials undergo complex stress evolution processes under different temperature conditions, which directly affects the safety and service life of structures. This paper introduces a measurement method based on fiber optic Fabry-Pérot interferometer (FPI) and Long period Bragg grating (LPFG) to evaluate the internal stress changes of stainless steel materials during heating. The FPI, with its high sensitivity, resistance to electromagnetic interference, and ease of remote operation, becomes an ideal monitoring tool. By conducting experimental tests on stainless steel samples under different temperature gradients, we can obtain stress variation curves to assess the stability of the materials and its response characteristics to temperature changes. The experimental results indicate that this sensor not only optimizes the measurement of internal stress in materials but also demonstrates a wide stress measurement range, making it suitable for various measurement targets. This lays a solid foundation for optimizing material design and enhancing structural safety levels.