Micro-CT analysis of geometrical distribution of filaments in double-twisted three-strand ropes: Comparison with analytical model

Studying the internal geometry of fibrous structures is critical for understanding their behaviour and improving their durability and performance. This study introduces an innovative micro-computed tomography (micro-CT) approach to analyse the internal geometry of three-strand ropes, focusing on filament orientation and its dependence on varying rope and strand twist configurations. Using advanced digital segmentation techniques, the micro-CT scans effectively isolate and quantify individual filaments, enabling precise measurements of filament-to-rope angles and their distributions. These experimental measurements are compared against a theoretical analytical model based on a double-helix structure, which accounts for strand retraction. The results reveal that the analytical model closely predicts filament orientations within the strand core but shows discrepancies near strand interfaces due to inter-strand forces. Higher strand-to-rope twist ratios reduce these deviations. This study not only underscores the limitations of current analytical models but also provides valuable insights into refining these models for more accurate predictions. A deeper understanding of this is important for improving the performance of fibrous ropes.