A study of internal defect testing with the laser-EMAT ultrasonic method

Area of Science:

• Materials Science
• Non-Destructive Testing
• Ultrasonic Wave Propagation

Background:

• Internal volume defects in metals pose significant challenges for structural integrity.
• Traditional ultrasonic testing methods can be limited in certain applications.
• Noncontact methods are desirable for efficient and safe material inspection.

Purpose of the Study:

• To develop and validate a noncontact ultrasonic method for detecting and evaluating internal volume defects in metals.
• To investigate the interaction of laser-generated ultrasonic waves with material defects.
• To establish a new quantitative evaluation method for defect characterization.

Main Methods:

• Utilizing laser generation for ultrasonic wave excitation.
• Employing electromagnetic acoustic transducers (EMATs) for noncontact detection.
• Developing a finite element model to simulate wave-defect interactions.
• Implementing a noncontact laser-EMAT ultrasonic testing experimental system.

Main Results:

• Observed directly scattered shear waves and mode-converted creeping waves on defect surfaces.
• Validated simulation results through experimental application of the laser-EMAT system.
• Demonstrated successful detection and location of defects using scattered shear waves.
• Achieved rapid defect evaluation via quantitative time-of-flight analysis of scattered and mode-converted waves.

Conclusions:

• The developed noncontact laser-EMAT technique is effective for detecting and locating internal metal defects.
• The study introduces a novel, quantitative method for rapid defect evaluation based on wave analysis.
• This approach offers a promising advancement in ultrasonic non-destructive testing for metals.