Development of an Eddy Current Sensor for Orthotropic Steel Decks Based on the Halbach Array

This is the authors' abstract. We don't add key points for this paper.

Eddy current testing (ECT) is a noncontact testing method, which has been recently applied in orthotropic steel decks detection for the through-deck type fatigue cracks. However, the detection sensitivity is quite sensitive to the lift-off distance of the sensor, due to the sharp decrease of magnetic field strength. In order to improve the sensitivity of ECT, a novel eddy current sensor based on the Halbach array was proposed. The new sensor structure of ECT was first designed and analyzed theoretically. Numerical simulations were then carried out to determine the geometric parameters of the Halbach array sensor, and the distribution of magnetic field as well as disturbance of the eddy current were discussed and compared with normal single sensor. The simulation results show that the structure of the Halbach array sensor proposed demonstrates an enhanced magnetic field on one side, which will lead to an increased amplitude of the ECT signal compared to the normal single sensor. The increased amplitude of the ECT signal is due to the stronger eddy current field generated by the Halbach array sensor on the specimen, which leads to more significant eddy current disturbances at the crack tip. The simulation results were finally verified by an experiment. The Halbach array sensor effectively improves the amplitude of the ECT signal by enhancing the magnetic field strength on the side of the detection area, thereby improving the sensitivity of the detection.