Abstract
The thermal strain and/or stress in CFRP plays an important rule in determining damage initiation and evolution around the interfaces such as the laminate interface and fiber/matrix interface, it arise from the difference between the longitudinal and the transverse CTE of carbon fibers. Experimental investigation has been made on the effect of anisotropic microstructure of carbon fiber on non-uniform thermal strain in CFRP during thermal loading. The measurement method on thermal deformation and strain distribution at different length scales was investigated by in-situ FE-SEM observation. A heating/cooling stage by Joule-Thomson effect was installed into the FE-SEM chamber. The composite material used was PAN-based (IM600) and pitch-based (K13D) carbon fiber reinforced epoxy matrix composites. The micro grid and random patterns were fabricated onto the CFRP surface. Electron moire method and digital image correlation method were applied to measure the multiscale deformation such as the fiber/matrix interface and the laminates interface acquired before and after loading. The nano scale thermal deformation inhomogeneity in CFRP was found at the interface due to the anisotropic microstructure of carbon fiber.
