In-situ SEM/micro-line methods for microscopic deformation and damage evolution analysis of composites

A novel experimental method based on temperature-controlled in-situ SEM (scanning electron microscope) combined with micro-lines printed on specimens was proposed to measure quantitatively the microscopic interlaminar deformation and damage evolution in composite laminates. Microscopic interlaminar deformation and damage near the transverse crack tip was clearly visualized under tensile loading for CFRP cross-ply laminates with and without the interlaminar resin-rich region. Temperature dependence of interlaminar shear deformation near transverse crack tips and the axial COD (crack opening displacement) was measured to demonstrate the effect of thermal residual stress, and then successfully compared with the modified two-dimensional (2D) approximate elastic analysis.