Non-destructive evaluation of the structural health of fiberglass composites: Using ultrasonic testing to improve performance and safety

Glass Fiber Reinforced Polymer (GFRP) materials are widely used across industries like aerospace and automotive due to their excellent strength-to-weight ratio and resistance to corrosion. Maintaining the quality of these materials is essential for operational safety, and Non-Destructive Testing (NDT) methods are effective tools for inspecting these composites. Among NDT methods, ultrasonic testing technology has been gaining prominence as a reliable technique for detecting flaws in composite materials. Traditional ultrasonic testing with single-element transducers, however, faces challenges such as high signal attenuation and a low signal-to-noise ratio (SNR). On the other hand, Phased Array Ultrasonic Testing (PAUT) offers the advantage of generating signals at specific distances and angles, making it particularly effective for composites with anisotropic properties. This article explores the detection of defects in composites using both bulk and guided waves. Findings suggest defects like cracks and delamination in GFRP test specimens can recognized using conventional ultrasonic and phased array methods. By optimizing the sensitivity of the phased array technique, even small defects—down to 0.8 mm at a depth of 25 mm and delamination at 22.5 mm- can be detected in GFRP blocks. The consistent alignment of fiber angles and uniformity of the material matrix enhance detection quality and sensitivity, leading to better identification of defect signals. Moreover, signals from phased array ultrasonics show superior characteristics to conventional ultrasonic techniques. Additionally, guided waves produced by the phased array method have demonstrated impressive capabilities in identifying defects in composite materials.