Debonding Detection in Aluminum/Rigid Polyurethane Foam Composite Plates Using A₀ Mode LAMB Wave EMATs

Area of Science:

• Materials Science
• Non-destructive Testing
• Acoustic Wave Propagation

Background:

• Aluminum/rigid polyurethane foam composite plates (ARCPs) are crucial for thermal insulation.
• Interface debonding during manufacturing significantly impairs ARCP thermal performance.
• Developing effective methods to detect this debonding is essential for quality control.

Purpose of the Study:

• To detect interface debonding in ARCPs using A0 mode Lamb waves.
• To investigate the influence of the rigid polyurethane foam (RPUF) layer on Lamb wave propagation and detection.
• To establish a reliable method for characterizing debonding length.

Main Methods:

• Utilized A0 mode Lamb waves, known for large out-of-plane displacement, for detection.
• Employed non-contact electromagnetic acoustic transducers (EMATs) for efficient Lamb wave generation and reception.
• Developed a finite element simulation model incorporating RPUF damping and interface bonding characteristics.

Main Results:

• Lamb wave energy transmission into the RPUF layer was minimal due to acoustic impedance mismatch.
• Significant energy attenuation within the thick, damped RPUF layer was observed.
• A nearly linear correlation was found between received signal amplitude and debonding length.

Conclusions:

• A0 mode Lamb wave propagation and subsequent energy attenuation in the RPUF layer serve as effective indicators of interface debonding.
• EMATs provide a practical and non-contact solution for detecting debonding in ARCPs.
• The study demonstrates a viable non-destructive testing approach for ARCPs, correlating signal characteristics with defect severity.