Performance optimization of harmonized flexible printed coils of axial magnetized magnetostrictive patch transducers for pipeline inspection

Currently, different types of magnetostrictive patch transducers (MPT) utilizing high magnetostriction patches, such as iron-cobalt alloys attached to the tested samples, have been proved to be effective electromagnetic acoustic transducers (EMAT). In 2019, an innovative guided wave-based MPT called the harmonized flexible printed coil (HFPC) sensor, consisting of a harmonized flexible printed coil sheet and a magnetized iron-cobalt patch, was proposed to replace conventional MPT. The HFPC sensor exhibits better performance than conventional MPT by generating a uniform magnetic field and triggering stronger signals. On the basis of previous research, this paper reported a newly optimized multilayer HFPC sensor, which considers coil inductance, capacitance, and other related parameters in a fixed-voltage AC power supply environment, which is rarely done by most researchers before. The optimized HFPC parameters were obtained from simulation studies and verified by the experimental investigation, where the performance was improved by 1.68 times compared to the old HFPC-based MPT.