Digital image and volume correlation with X-ray micro-computed tomography for deformation and damage characterisation of woven fibre-reinforced composites

Woven composites have complex deformation and damage behaviour which surface-based characterisation methods struggle to capture. This work combines surface digital image correlation (DIC) with 3D micro-computed tomography (μCT) and corresponding digital volume correlation (DVC) as a non-contact approach to assess the deformation and damage of woven thermoplastic composites. Specimens underwent load-relaxation tensile tests to 90% ultimate extension, inducing micro-scale damage and modest permanent architectural deformation. Results showed that differences in the loading direction and corresponding fibre waviness cause significant differences in surface topography, strain, and internal out-of-plane deformation. The average internal εz that remained after loading was 0.32% (warp) and 1.54% (weft). μCT images of specimen microstructure combined with DIC allowed depth-wise examination of surface features such as transverse cracking. DVC and μCT are effective tools for characterising woven composite deformation, imperceptible to surface-based methods, and have significant future potential for improving finite element simulations.