Abstract:Finite element simulation and experiment methods are employed to analyze the detection ability of flexible eddy current sensor for detecting the orientation angle and depth of a simulated crack defect when the circular coil is in different bending angles. The obtained results show that the bending of the circular coil leads the isotropic eddy current field to change to unidirectional eddy current field. No matter the flexible eddy current sensor works under self induction mode or mutual induction mode, the sensitivity of the flexible eddy current sensor to the crack faults with different orientation angles decreases. For instance, when the bending angle of the coil is 30°, the sensitivity of the flexible eddy current sensor to the crack with an orientation angle of 90° in self and mutual induction modes reduces by 7% and 45%, respectively. In addition, the coil bending causes that the recognition ability of the flexible eddy current sensor to the crack orientation angle and depth monotonously decreases as the bending angle of the coil increases. Under mutualinduction mode the flexible eddy current sensor achieves better recognition ability to crack orientation angle and depth compared with the case under the selfinduction mode. The influence of the coil bending occurred in the shape matching between the coil and curved surface on the performance of the sensor can not be ignored. A reasonable coil bending angle range should be selected when designing the flexible eddy current sensor.