Meso-scale study of non-linear tensile response and fiber trellising mechanisms in woven composites

The non-linear deformation response of plain woven carbon fiber-reinforced composites is experimentally studied at meso-scales. Stereovision digital image correlation is utilized to capture the full-field strain distribution over a 10 × 10 mm² area of interest located at the center of the specimens. The evolution of local strains on the fiber bundles and matrix-rich regions as a function of loading is extracted. The effect of fiber orientation angle on fiber bundles stretch ratio and their angle of rotation (fiber trellising) and the related underlying failure mechanisms are analyzed using the measured full-field displacement data. The results indicate that the local load-bearing mechanisms are different in on-axis and off-axis loading conditions, whereas the larger global failure strain noticed in off-axis conditions is attributed to the occurrence of fiber rotation. The fiber trellising is also shown to promote high local shear strain and consequently leads to the protrusion of the matrix material on the deformed specimen surface.