The Use of Flexible Ultrasound Transducers for the Detection of Laser-Induced Guided Waves on Curved Surfaces at Elevated Temperatures

Abstract

In this study, a flexible ultrasonic transducer (FUT) was applied in a laser ultrasonic technique (LUT) for non-destructive characterization of metallic pipes at high temperatures of up to 176 °C. Compared with normal ultrasound transducers, a FUT is a piezoelectric film made of a PZT/PZT sol-gel composite which has advantages due to its high sensitivity, curved surface adaptability and high temperature durability. By operating a pulsed laser in B-scan mode along with the integration of FUT and LUT, a multi-mode dispersion spectrum of a stainless steel pipe at high temperature can be measured. In addition, dynamic wave propagation behaviors are experimentally visualized with two dimensional scanning. The images directly interpret the reflections from the interior defects and also can locate their positions. This hybrid technique shows great potential for non-destructive evaluation of structures with complex geometry, especially in high temperature environments.

Possibility of Piezoelectric Sensor to Monitor Onshore Pipeline in Real Time Monitoring

“…The experiment utilized the electromechanical effect on piezoelectric sensors from flexible Macro Fiber Composite (MFC) [9]. Application of piezoelectric for sensor also used for flexible ultrasonic transducer (FUT), which is made of PZT sol-gel composite with high sensitivity, adaptability and high temperature durability [11]. Others method to detect defect of pipeline were developed by Du Guofeng et.al, identification of crack damage in pipe structure using a stress wave propagation with piezoelectric transducers [2].…”

Recent Advances in Flexible Ultrasonic Transducers: From Materials Optimization to Imaging Applications

“…Compared to flexible US array transducers, the flexible single-element US transducers have a low complexity, a simple fabrication process and a high center frequency. Fabricating the flexible single-element US transducers based on the piezoelectric film (i.e., ZnO, AlN, PZT and PVDF) and the flexible piezocomposites is the most promising strategy [ 50 , 51 ]. Kobayashi et al and Hou et al designed a flexible single-element US transducer based on PZT or ZnO thin film, with a center frequency of 13.1 MHz and 29 MHz, respectively [ 1 , 33 ], as shown in Figure 3 b [ 1 , 33 ].…”

Nonlinear Vibration Analysis of Beam and Plate with Closed Crack: A Review

“…In complex shapes and hazardous environments, Wu TC et al [67] employ fully non-contact NUT based on laser ultrasound (LUT) on closed surface cracks. The result reveals a weak second harmonic, which is caused by the material's or measuring system's nonlinearity.…”