Using cross-correlations of elastic diffuse fields for attenuation tomography of structural damage

Area of Science:

• Non-destructive testing
• Wave propagation analysis
• Materials science

Background:

• Diffuse vibrations in structures can indicate damage.
• Laser Doppler vibrometry offers precise, non-contact measurement capabilities.
• Lamb wave propagation is sensitive to material properties and defects.

Purpose of the Study:

• To develop a non-destructive method for detecting structural damage.
• To image simulated damage using wave attenuation tomography.
• To analyze the propagation of diffuse vibrations in complex geometries.

Main Methods:

• Utilizing a scanning laser Doppler vibrometer to measure vibrations (50-150 kHz) on an aluminum plate.
• Generating diffuse vibrations via pulsed laser impacts.
• Calculating pairwise cross-correlations of the vibration field to estimate wave arrival times and amplitudes.
• Applying attenuation tomography based on amplitude variations to image simulated damage.

Main Results:

• Successfully estimated the first antisymmetric Lamb mode direct arrival between measurement points.
• Demonstrated the capability of attenuation tomography to visualize simulated structural damage.
• Observed relative amplitude variations in wave arrivals correlated with damage presence.

Conclusions:

• The proposed method effectively uses diffuse vibration analysis and attenuation tomography for structural damage detection.
• Laser Doppler vibrometry is suitable for mapping wave propagation and identifying damage in complex structures.
• This technique shows promise for non-destructive evaluation of materials and components.