Abstract
Carbon fibre sheet-moulding compounds (CFRTP-SMCs) offer an attractive balance of mechanical performance, manufacturability and cost, yet their highly heterogeneous mesostructure makes damage initiation difficult to predict. This study investigates how tape configuration influences the onset of damage using a combined in situ digital volume correlation (DVC) and principal component analysis (PCA) framework. Four tape architectures, varying in thickness and strand length, were examined to determine whether geometric modifications alter either the global mechanical response or the underlying failure mechanisms. A bespoke PCA module integrated into Avizo enabled efficient correlation of first principal strain fields with local microstructural descriptors over the full DVC mesh, extending previous studies that focused only on local crack regions. Across all configurations, samples exhibited the same dominant damage sequence, strain localised in resin-rich regions and tape junctions, followed by inferred fibre–matrix decohesion and matrix micro-cracking both occurring below XCT resolution and culminating in macroscopic fracture. While these mechanisms remained unchanged, variations in tape geometry influenced strand alignment and load redistribution, producing measurable differences in stiffness and strength.
PCA further revealed a strong correlation between first principal strain and local resin density, underscoring the critical role of resin pockets in triggering localisation.Overall, the results show that tape configuration modifies global performance through geometric effects, but does not alter the fundamental microstructural drivers of damage. The combined DVC–PCA methodology provides a robust and transferable experimental framework for identifying the key microstructural drivers of strain localisation in heterogeneous discontinuous CFRTP-SMCs and informing physically grounded modelling approaches. Read more…