Influence of magnetostrictive strip size in the generation of L(0,2) and T(0,1) wave mode using magnetostrictive patch transducer (MPT)

Magnetostrictive patch transducer (MPT) is widely used to generate ultrasonic guided waves in non-ferromagnetic materials. MPT majorly consist a solenoid, biasing magnet and magnetostrictive strip material. The objective is to investigate the influence of magnetostrictive strip size in the generation of L(0,2) and T(0,1) wave mode at a low-frequency regime using finite element and experimental study. To understand the physics of wave characteristics, a 3-D finite element model was developed. For simulating the effect of magnetostrictive strip size, a displacement field was applied in an area (transduction region) whose dimension is equal to the strip size. The effect was analysed by varying the length and width of the transduction region. For experimental study, a 3.6-meter 3-inch aluminium pipe with a notch defect is used, and the size of the strip varied along the axial and circumferential direction of the pipe. The effect of strip size in the acquired signal is characterized based on the signal strength, SNR and the wave modes generated. This study leads to the efficient optimization of magnetostrictive patch transducer in the generation of L(0,2) and T(0,1) wave modes for long-range inspection.