Hot target inspection using a welded fibre acoustic wave piezoelectric sensor and a laser-ultrasonic mirror scanner

Abstract

The direct attachment of piezoelectric transducers onto hot targets raises formidable challenges as piezoelectric transducers lose their piezoelectric characteristics at elevated temperatures or debond due to thermal expansion coefficient mismatches. We developed a welded fibre acoustic-wave PZT (FAWPZT) sensor to alleviate these temperature limitations. One end of the FAWPZT sensor, made from a stainless steel fibre, was welded onto a stainless steel target plate and the other end was bonded to a PZT sensor. An ultrasonic wave propagation imaging (UWPI) system consists of a laser mirror scanner and a Q-switched pulsed laser (QPL) acting as a non-contact ultrasonic generator was then used to scan a hot target surface with an artificial 2 mm-sized open crack. The result was presented in the form of an ultrasonic wave propagation movie. The damage was detected as a wavefield scattering from the damaged location and its size was evaluated from the plot of amplitude distribution along the propagating wavefront. Sensor performance was briefly discussed and the results confirmed that a FAWPZT sensor combined with a UWPI system has good potential for implementation in hot target integrated structural health management.

Composite NDE using full-field pulse-echo ultrasonic propagation imaging system

“…The pulseecho through-the-thickness ultrasound signals are captured at all scan points throughout the scan area based on FF PE UPI system in real-time. The captured signals are immediately rearranged into three-dimensional array which is a fullfield ultrasound as large as the scan area [5]. This technique is simultaneously operated with scanning process thus the result is instantly generated after completed scan.…”

Using Field Programmable Gate Array Hardware for the Performance Improvement of Ultrasonic Wave Propagation Imaging System

“…3, is formed and ready for video generation [8]. A similar procedure is applied for the post processing system, with the data acquisition from DAQ card being replaced by the data transfer from the computer itself, using the already stored data.…”

“…The ultrasonic propagation imaging method is among those regarded as highly efficient and effective methods for fatigue tests or damage visualization and/or localization [1][2][3][4][5][6][7][8][9]. This technique depends on ultrasonic signal acquisition through a high speed data acquisition system, from piezoelectric sensors attached to any inspecting surface or structure.…”

Fully Noncontact Wave Propagation Imaging in an Immersed Metallic Plate with a Crack

“…In the experiments, the scanning area was repeatedly scanned 10 times. The ten signals obtained at each scanning grid point were averaged, and the averaged waveforms were used as the input data for the UWPI algorithm [12] to generate the ultrasonic wave propagation video clips. As compared between Figures 6(a) and 8(b) and between Figures 7(a) and 8(c), the respective SNRs under the water-and glycerin-immersed plate conditions were highly improved.…”