An excitation coil layout method for improving the sensitivity of a rosette flexible eddy current array sensor

Abstract

Flexible eddy current array sensor has the characteristics of flexibility, light weight and convenient installation, and has great application prospects in metal structure crack monitoring. In allusion to the low sensitivity of traditional rosette flexible eddy current array sensor to crack identification, a co-directional excitation coil layout method is proposed, which significantly improves the sensitivity of sensor to crack identification . Firstly, by establishing the finite element model, the sensitivity of three sensing coils of the traditional sensor to crack identification is calculated to be 4.1%, 1.7% and 3.5%, respectively. The conclusion that the disturbed backflow between the excitation coils affects the sensitivity of each sensing coil to crack identification is obtained. In order to improve the sensitivity of the sensor, a new type of sensor using the co-directional excitation layout is proposed by changing the layout of the excitation coil. The simulation results show that the sensitivity of three sensing coils to crack identification is increased by 11.2, 43.1 and 36.0 times, respectively. Then, the sensitivity tests of the two sensors are carried out. The experimental results show that the sensitivity of three sensing coils of the sensor adopted co-directional excitation layout increases sequentially, which is 8.9, 23.7 and 13.3 times higher than the traditional sensor, indicating that the sensor adopted co-directional excitation layout is more sensitive to crack identification. Finally, the error analysis shows that the difference between the sensitivity of experimental results and simulation results is caused by the difference of lift-off. The research results privide an important way to improve the sensitivity of crack identification.

Series and interactive sensing coil layouts for reducing sensing channels of flexible eddy current array sensor

“…He et al (2017) integrated the FECA sensor and gasket to monitor the bolt hole edge crack. A FECA sensor with the co-directional excitation layout is proposed in reference (Fan et al , 2020), which greatly improves the sensitivity of the sensor to crack identification. But the sensor has six sensing coils, and each sensing coil has an output channel.…”

A quantitative crack monitoring method based on crack disturbed voltage

“…Li et al (2016) and Ma et al (2020) have used the real and imaginary parts of the trans-impedance to characterize crack propagation and studied the influence of crack propagation on the real and imaginary parts of the trans-impedance. Fan et al (2020) also have used the relative change rate of trans-impedance amplitude as the sensitivity to characterize crack propagation. Goldfine et al and Sheiretov et al have established a lift-off-conductivity two-dimensional grid of the sensor, and the change of conductivity by crack propagation is obtained to judge the damage.…”

Quantifying Hole-Edge Crack of Bolt Joints by Using an Embedding Triangle Eddy Current Sensing Film

“…They also discovered that exciting currents in adjacent wingdings flowing in same directions instead of opposite directions can increase the output signal and sensitivity. Fan et al [ 21 ] further studied the effect of the excitation layout on the sensor sensitivity and the results show that the sensitivity was increased up to 43.1 times in simulation and 23.7 times in an experiment when the co-directional excitation coil layout was applied. Furthermore, research projects into the temperature compensation for RECA sensor have also been conducted in [ 22 , 23 ].…”