Noncontact pulsed laser-scanning laser Doppler vibrometer (PL-SLDV) phased array imaging for damage detection in...

Area of Science:

• Materials Science
• Non-destructive Testing
• Wave Physics

Background:

• Traditional guided wave phased arrays use wired ultrasonic transducers, limiting reconfigurability and contactless inspection.
• Rapid inspection of large composite panels is crucial for structural integrity.

Purpose of the Study:

• To present a fully noncontact guided wave phased array imaging approach for composite materials.
• To develop a system capable of damage detection without prior knowledge of material properties.

Main Methods:

• Utilized a dual laser-based system: pulsed laser for guided wave generation and scanning laser Doppler vibrometer for sensing.
• Implemented synthetic phased array beamforming with an improved delay-and-sum algorithm accounting for dispersion.
• Integrated wavefield analysis to extract dispersion relations from experimental data.

Main Results:

• Successfully demonstrated damage imaging and detection of multiple defects in composites using the noncontact phased array system.
• The system overcomes dispersion and directional dependency in anisotropic materials.
• Identified multiple guided wave modes (A0, S0, SH0, A1, S1, SH1) generated by pulsed lasers.

Conclusions:

• The proposed pulsed laser-scanning laser Doppler vibrometer (PL-SLDV) system offers a reconfigurable, noncontact solution for guided wave phased array imaging.
• This method enables effective damage detection in composites from a distance, adaptable to various array configurations.
• The approach provides valuable insights into PL-generated guided waves and their modes for advanced NDT applications.