Lightning damages to wind turbine blades increase as the size of wind turbine becomes larger. The damages are quite serious since it contributes to high cost of repairs and loss of electric power production. Since natural plant fibres receive attention nowadays due to low density and high specific strength, the usage of natural fibre to replace synthetic fibre in fabricating the turbine blade will promote a green renewable material. As the application of biocomposite for wind turbine blade has been explored, the effect of lightning strike damage has been required for further test investigation. This article explores the comparative results of performing lightning strike damage testing on composite (fibreglass) and biocomposite (flax fibre) wind turbine blades with protective metal mesh materials. The damage assessments were performed using visual non-destructive inspection methods and piezoelectric sensor as part of structural health monitoring. From the result, it is found that fibreglass blade experienced larger damage area compared to flax fibre blade based on the visual test conducted.

The detection of impact and depth defects in Glass Fiber Reinforced Polymer (GFRP) composites has been extensively studied to develop effective, reliable, and cost-efficient assessment methods through various Non-Destructive Testing (NDT) techniques. Challenges in detecting these defects arise from varying responses based on the geometrical shape, thickness, and defect types. Long Pulse Thermography (LPT), utilizing an uncooled microbolometer and a low-resolution infrared (IR) camera, presents a promising solution for detecting both depth and impact defects in GFRP materials with a single setup and minimal tools at an economical cost. Despite its potential, the application of LPT has been limited due to susceptibility to noise from environmental radiation and reflections, leading to blurry images. This study focuses on optimizing LPT parameters to achieve accurate defect detection. Specifically, we investigated 11 flat-bottom hole (FBH) depth defects and impact defects ranging from 8 J to 15 J in GFRP materials. The key parameters examined include the environmental temperature, background reflection, background color reflection, and surface emissivity. Additionally, we employed image processing techniques to classify composite defects and automatically highlight defective areas. The Tanimoto Criterion (TC) was used to evaluate the accuracy of LPT both for raw images and post-processed images. The results demonstrate that through parameter optimization, the depth defects in GFRP materials were successfully detected. The TC success rate reached 0.91 for detecting FBH depth defects in raw images, which improved significantly after post-processing using Canny edge detection and Hough circle detection algorithms. This study underscores the potential of optimized LPT as a cost-effective and reliable method for detecting defects in GFRP composites.

The utilization of natural fibers as sustainable materials in composites has gained significant attention in recent years. This study investigates the tensile and low-velocity impact behavior of flax fiber-reinforced composites modified with multi-walled carbon nanotubes (MWCNTs). The primary objective is to evaluate the mechanical performance enhancements achieved by incorporating MWCNTs into woven flax fibers through a vacuum bagging process. Flax fiber with varying MWCNT concentrations (0-3 wt.%) were fabricated and subjected to tensile and drop-weight impact tests. The tensile test results revealed that the incorporation of MWCNTs significantly improved the tensile strength of the composites, with the FF/PE-CNT3 sample exhibiting a 6.23% increase compared to the control sample (FF/PE). Scanning Electron Microscopy (SEM) analysis demonstrated better dispersion and interaction of MWCNTs within the composite matrix, leading to enhanced load transfer and mechanical properties. Impact tests showed a marked increase in energy absorption with higher MWCNT content. The FF/PE-CNT3 sample absorbed 43.81 J at 30 J impact energy, indicating a 31.81% improvement over the control sample. The enhanced energy absorption is attributed to the excellent interfacial bonding and effective load distribution facilitated by the MWCNTs. These findings suggest that MWCNT-modified flax fiber composites exhibit superior mechanical properties, making them promising candidates for applications requiring high strength and impact resistance. The study contributes to the development of advanced natural fiber-reinforced composites with improved performance for sustainable engineering applications.