A Magnetostrictive Ultrasonic Transducer for Defect Monitoring of Rotating Bolts

This study addresses the challenges of monitoring bolt defects during high-speed rotation by proposing a novel magnetostrictive patch-type ultrasonic transducer. The ultrasonic transducer incorporates Terfenol-D material, which has a giant magnetostriction coefficient. The transducer can be used for non-contact defect monitoring in bolts under dynamic working conditions such as vibration and rotation. First, we establish a multiphysics-coupled finite element simulation model of the magnetostrictive patch ultrasonic transducer. Based on this mode, we optimize the parameters affecting the transducer performance. These parameters include the dimensions of the permanent magnet, the driving voltage amplitude, and the coil parameters. Second, we construct a rotating experimental platform for monitoring the bolt defect. It validates that the lift-off of the optimized transducer can be reached no less than 7 mm. Finally, we examine how the rotation speed affects the received ultrasonic signals, varying the speed from 0 to 1000 rpm with a lift-off of 2 mm. We find that the rotation speed shows no obvious effect on the amplitude of the ultrasonic echoes. This study proposes a feasible technical solution for the online detection of cracks in rotated bolts.