Computational Analysis of Defect Signals of All-Round Pipe Inspection using HTS-SQUID-based Guided Wave Testing

In this paper, we demonstrated all-round inspections on aluminum pipe samples with different types of defects using HTS-SQUID-based ultrasonic guided waves, and analyzed defect signals using computer simulation. In order to transceive uniformly distributed T (0, 1) mode guided waves on aluminum pipe samples, two pairs of nickel thin plates magnetized in the longitudinal direction using a solenoid coil were glued on each sample with different angle arrangement. They were used as magnetostriction-based guided wave transceivers, and a coil was wound around one pair of the nickel plates as a transmitter, while the other was used as a receiver. Artificial defects, such as a slit perpendicular to axis of the pipe and inclined slit, were made on the respective pipe samples. All-round inspection of the T (0, 1) mode guided waves around circumferences of the pipes were carried out by rotating the pipe for 360° with step of 45°. Signals of reflected wave from the artificial slits were well detected. We simulated distribution of the guided waves propagating on the pipes with the slits using an ultrasonic simulator for two-dimensional models. The guided wave signal distributions including the defect signals obtained by experiments and simulations agreed well.