Defect Visualization of a Steel Structure Using a Piezoelectric Line Sensor Based on Laser Ultrasonic Guided Wave

Area of Science:

• Materials Science
• Non-Destructive Testing
• Acoustics

Background:

• Traditional single piezoelectric sensors have limited coverage for laser ultrasonic guided wave detection.
• Multi-channel sensors present challenges with wiring, installation, and signal acquisition efficiency.
• Existing methods struggle with comprehensive defect visualization and precise localization.

Purpose of the Study:

• To introduce and evaluate a novel piezoelectric line sensor for laser ultrasonic defect detection.
• To overcome the limitations of single and multi-channel sensors in terms of coverage and efficiency.
• To demonstrate the feasibility of using a line sensor for precise defect visualization and characterization.

Main Methods:

• Laser irradiation of a test object using a Nd:YAG 532 nm Q-switched laser.
• Generation of thermoelastic waves propagating as ultrasonic guided waves.
• Acquisition of ultrasonic signals using novel I- and L-shaped piezoelectric line sensors attached to a steel structure.
• Simulation and analysis of defect-induced distortions in ultrasonic propagation images.

Main Results:

• The piezoelectric line sensor successfully acquired ultrasonic signals from laser excitation.
• Defect-induced distortions in the ultrasonic propagation image were clearly visualized.
• The line sensor demonstrated more precise and accurate defect detection compared to a single piezoelectric sensor.
• Three simulated defects were effectively identified and localized.

Conclusions:

• The piezoelectric line sensor is a feasible and effective tool for laser ultrasonic defect detection.
• This novel sensor design overcomes the limitations of conventional piezoelectric sensors.
• The technology enables enhanced visualization and more accurate detection of subsurface defects.