Characterisation of off-axis tensile behaviour and mesoscale deformation of woven carbon-fibre/PEEK using digital image correlation and X-ray computed tomography

The architectural intricacy of multi-ply woven composites, caused by differences in layer alignment, introduces complexity into their mesoscale response to on- and off-axis tensile loading. To better understand the relationship between architecture and deformation response, this work combines digital image correlation (DIC) and 3D micro-computed tomography (mu CT) to examine deformation for 0 degrees, 15 degrees, 30 degrees and 45 degrees specimens. Tensile tests were conducted with a four-layer plain woven carbon/polyetheretherketone (C/PEEK) laminate. In addition to the evident variance of mechanical properties between orientations, significant mesoscale differences in topography and strain were observed resulting from the layer alignment of individual specimens. Alignment of the top two surface layers induced distinct topographical peaks under extension, whereas nested architectures formed continuous topographical ridges. Matching observed surface strains around microstructural cracks identified in mu CT images revealed both inter-tow and intra-tow shearing during off-axis extension and corresponding fibre reorientation, which effectively illustrates the potential benefits from combining DIC and mu CT.

Automated summary

This study investigates the deformation response of multi-ply woven composites at different angles by combining digital image correlation (DIC) and 3D micro-computed tomography (mu CT). Significant mechanical property variances and topographical/strain differences were observed between orientations due to layer alignment. Additionally, inter-tow and intra-tow shearing during off-axis extension and corresponding fiber reorientation were identified, highlighting the benefits of combining DIC and mu CT.