The Wrinkles Characterization in GFRP Composites by Infrared Active Thermography

Area of Science:

• Materials Science
• Non-Destructive Testing
• Composite Materials

Background:

• Wrinkles are common defects in Glass Fiber Reinforced Plastic (GFRP) composites, potentially compromising structural integrity.
• Effective detection methods are crucial for structural health monitoring (SHM) of composite components, especially in demanding applications like wind turbine blades.
• Infrared thermography (IRT) offers a non-contact method for defect detection in materials.

Purpose of the Study:

• To evaluate the effectiveness of active infrared thermography for detecting wrinkles in GFRP composite structures.
• To compare transmission and reflection measurement techniques for IRT-based wrinkle detection.
• To assess the influence of GFRP weave patterns and gelcoat surfaces on thermography's detection capabilities.

Main Methods:

• Manufactured GFRP plates with twill and satin weave patterns using vacuum bagging, incorporating wrinkles at various locations.
• Employed active infrared thermography in both transmission and reflection modes to inspect the GFRP plates and a turbine blade section.
• Analyzed thermal parameters to assess damage detection and identification capabilities.

Main Results:

• Active infrared thermography proved effective in detecting and localizing wrinkles in GFRP composite structures.
• The transmission IRT setup enabled not only detection and localization but also accurate identification of defects.
• The reflection IRT setup is suitable for damage detection systems integrated with non-destructive testing software.
• The type of fabric weave (twill vs. satin) had a negligible impact on the quality of wrinkle detection.

Conclusions:

• Active infrared thermography is a viable technique for structural health monitoring of GFRP composites, particularly for wrinkle detection.
• Transmission IRT offers superior capabilities for defect identification compared to reflection IRT in this context.
• The findings support the use of IRT for quality control and maintenance of composite structures, including wind turbine blades.