Ultrasonic Analytic-Signal Responses From Polymer-Matrix Composite Laminates

Area of Science:

• Materials Science
• Non-destructive Testing
• Acoustic Metamaterials

Background:

• Composite laminates are crucial in aerospace and automotive industries.
• Traditional ultrasound methods primarily focus on external reflections.
• Internal ply responses in composites have been underutilized for defect detection.

Purpose of the Study:

• To develop advanced ultrasound modeling techniques for analyzing internal ply reflections in composite laminates.
• To investigate the potential of analytic signal processing for characterizing composite microstructure.
• To identify and track resin-rich layers and manufacturing anomalies within composite components.

Main Methods:

• Utilized advanced modeling techniques to interpret complex ultrasonic reflections from resin layers between plies.
• Applied analytic signal analysis, focusing on instantaneous amplitude, phase, and frequency.
• Correlated ultrasonic data with experimental results from real composite specimens, X-ray computed tomography, and microsections.

Main Results:

• The analytic signal provides 3-D characterization of composite microstructure.
• Phase locking to ply interfaces and distinct instantaneous frequencies for first/last plies were observed.
• Successfully tracked thin resin layers through various anomalies like ply drops, tape gaps, and wrinkles.
• Demonstrated capability in identifying defects such as delaminations.

Conclusions:

• The developed method offers crucial insights into the conformance of as-manufactured composite components to design specifications.
• Ultrasound's internal ply response analysis is a powerful tool for detailed microstructure characterization and defect detection.
• This approach enhances non-destructive evaluation of complex composite structures.