52 / 2025-05-13 21:35:55

Study on Monitoring Reliability of Flexible Eddy Current Sensor in Variable Temperature Environment

SHM; Reliability; Flexible eddy current sensor; Variable temperature

The aircraft structure is often subjected to drastic changes in ambient temperature during service, and the variable temperature environment will cause false alarm and missing alarm of the structural crack monitoring system. In this work, the monitoring reliability of the flexible eddy current sensor under variable temperature environment is studied. The influence mechanism of temperature change on the output of the flexible eddy current sensor is analyzed. The influence law of crack propagation and temperature change on the output of the sensor is studied through experiments, and a three-dimensional finite element model of the structure with cracks is established. The influence mechanism of temperature change on sensor output is analyzed qualitatively. The basic idea of the forward equivalent model of the sensor is proposed, and the semi-analytic forward equivalent model is established. By using the forward equivalent model, the sensor multi-parameter feature grid reflecting the relationship between material conductivity, lift-off distance and sensor output is obtained. Research on temperature interference suppression method based on inverse model is carried out, and the inverse solution method of sensor is established to realize the inverse solution of the conductivity and lift-off distance of the measured material. The influence of crack and temperature on the conductivity signal is explored by using the inverse solution method of sensor, and a flexible eddy current sensor with the function of temperature interference suppression is designed and developed. The characteristic signal of the sensor is defined, the influence of ambient temperature change on the output of the new sensor is studied, and the ability of the new sensor to eliminate the influence of ambient temperature change is verified. This work expands the solution idea of improving the reliability of sensor monitoring under variable temperature environment.