Nondestructive Analysis of Debonds in a Composite Structure under Variable Temperature Conditions

Area of Science:

• Materials Science
• Non-Destructive Testing
• Structural Health Monitoring

Background:

• Adhesively-bonded composite structures are susceptible to debonds, impacting their integrity.
• Effective monitoring of these damages is crucial for operational safety, especially under variable thermal conditions.

Purpose of the Study:

• To develop and validate a non-destructive analysis technique for detecting debonds in carbon-fibre reinforced composite structures.
• To investigate the influence of variable temperature conditions on debond detection using ultrasonic guided waves.

Main Methods:

• Experimental analysis and numerical simulations of ultrasonic guided wave propagation.
• Utilizing a distributed piezoelectric sensor network for signal acquisition.
• Developing a monitoring strategy based on debond-induced differential amplitude phenomena.

Main Results:

• Debonds significantly reduce wave mode amplitudes, with effects amplified by higher temperatures and larger debond sizes.
• The proposed online monitoring strategy successfully localized hidden debonds.
• Generated debond index maps demonstrated high identification potential.

Conclusions:

• The study establishes the effectiveness of a damage index derived from guided wave signal features for localizing and characterizing debond damages.
• The proposed method shows significant potential for real-time structural health monitoring of operational composite structures.
• Accuracy was validated against infrared thermography, confirming the robustness of the technique across variable conditions.