A new rosette-like eddy current array sensor with high sensitivity for fatigue defect around bolt hole in SHM

Abstract

Boosting the sensitivity of eddy current sensors is one of the challenges of non-destructive testing to improve structure health monitoring. Rosette-like eddy current sensors have the best application prospect in structure health monitoring to detect fatigue-induced defects around a bolt hole. To boost the sensitivity of this kind of sensor, a new rosette-like eddy current array sensor is proposed. Same-direction exciting currents are used to make the eddy current distribution more sensitive to detect defect propagation. Moreover, a new layout of pickup coils and a graph algorithm are proposed to improve the sensor's angular resolution. Through finite element simulation and experimental tests, the eddy current distribution and the output signal during defect propagation of a traditional sensor and a new one are compared. Results show that the proposed sensor has higher sensitivity in detecting defect propagation than the traditional one.