Multi-Variant Damage Assessment in Composite Materials Using Acoustic Emission

Area of Science:

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

Background:

• Fibre-reinforced polymers (FRPs) offer excellent mechanical properties but exhibit complex damage mechanisms.
• Conventional inspection methods struggle to detect diverse and simultaneous damage modes in anisotropic FRPs.
• Acoustic emission (AE) techniques show promise for structural health monitoring but require advanced analysis.

Purpose of the Study:

• To develop and validate a novel, real-time methodology for characterising and quantitatively assessing damage in FRPs using AE.
• To differentiate and identify multiple, co-occurring damage mechanisms in carbon fibre composites.
• To improve the early detection and assessment of critical damage events for enhanced structural integrity.

Main Methods:

• Implementation of a multi-variant frequency assessment of acoustic emission (AE) signals.
• Application of the fast Fourier transform (FFT) to analyze multiple frequency peaks within AE data.
• Comparative analysis with wavelet transform methods for validation and performance benchmarking.

Main Results:

• Successful identification of five distinct damage mechanisms in carbon fibre composites based on specific frequency ranges: matrix cracking (100-200 kHz), delamination (205-265 kHz), debonding (270-320 kHz), fibre fracture (330-385 kHz), and fibre pullout (395-490 kHz).
• Demonstrated earlier detection of critical damage, with delamination identified approximately 28 seconds sooner compared to conventional techniques.
• Provided a more accurate quantitative assessment of structural health in FRPs.

Conclusions:

• The proposed multi-variant frequency assessment methodology offers a significant advancement in AE-based damage detection for FRPs.
• This technique enables timely identification and characterization of multiple damage modes, crucial for structural integrity.
• The findings facilitate proactive maintenance for large-scale FRP structures, improving reliability and reducing operational costs.