Evaluation and Defect Detection in L-Shaped GFRP Laminates by Infrared Thermography

Area of Science:

• Materials Science
• Non-destructive Testing
• Polymer Composites

Background:

• Glass fiber-reinforced polymer (GFRP) laminates offer excellent mechanical properties and cost-effectiveness.
• Fiber waviness or wrinkles are common defects in multilayered GFRP laminates, especially in thick, curved structures.
• These defects significantly reduce the mechanical performance of GFRP laminates, necessitating early detection methods.

Purpose of the Study:

• To investigate the efficacy of active infrared thermography for detecting wrinkles in curved, multilayered GFRP laminates.
• To assess the impact of manufacturing processes on wrinkle formation and reduction.
• To analyze factors influencing the interpretation of thermographic data for defect detection.

Main Methods:

• Artificial wrinkles were introduced into curved GFRP laminate samples.
• Active infrared thermography was employed to detect and analyze the wrinkles.
• Sample shape deformations were evaluated against the mold and nominal shape.
• Microscopic analysis was used to assess wrinkle size.

Main Results:

• Active infrared thermography successfully detected wrinkles in thick, curved GFRP laminates.
• The out-of-autoclave manufacturing process was shown to reduce wrinkles without compromising the internal laminate structure.
• Interpreting thermographic results was challenging due to structural curvature, non-uniform heating, and setup configuration.

Conclusions:

• Active infrared thermography is a viable method for detecting wrinkles in complex GFRP structures.
• Careful consideration of geometric and thermal factors is crucial for accurate thermographic defect assessment.
• Further research may optimize thermographic techniques for curved composite structures.