Meso-scale constitutive response of woven composites subjected to large deformation

This work aims to study the local large deformation response of woven composites at mesoscopic scales. Woven carbon reinforced composite specimens are subjected to in-plane axial quasi-static tension in parallel (on-axis) and inclined (off-axis) directions relative to the primary fiber directions, while the deformation response on the fiber-rich and matrix-rich regions on the surface of the sample is captured and analyzed in-situ using stereo-vision digital image correlation at sub-millimeter length scale. The evolution of local strain components are extracted and analyzed, and later used to explain the local constitutive response of the composite samples at various locations on the surface of the composite laminate. Appreciable strain heterogeneity is observed in both on-and off-axis specimens; whereas the degree of the heterogeneity depends on the angle between the principal fiber bundles and the axial loading direction. Attempts are also made to extract and characterize the local constitutive curves over fiber bundles and matrix-rich areas within the material, allowing for the acquisition of effective stress-strain curves at meso-scales. The approach proposed and discussed in this work has the potential to facilitate the establishment of a correlation between the globally applied load and locally developed strains used to model the progressive damage at mesoscopic scales in woven composite laminates under large deformation conditions.