Measurement method of multi scale thermal deformation inhomogeneity in CFRP using in situ FE-SEM observations

The measurement of nano scale thermal deformation and strain inhomogeneity in the transverse direction in carbon fiber-reinformed polmer (CFRP) in the temperature range 170-370 K has been carried out by in-situ Field Emission Scanning Electron Microscopy (FE-SEM) observation using a heating and cooling stage in the FE-SEM chamber. A grid pattern and also random patterns were drawn on the polished sample surface at different length scales. The electron moiré method was applied to measure the macroscopic deformation and the digital imaging correlation method was applied to measure the nano-scale deformation around the fiber/matrix interface. The strain inhomogeneity of the pitch-based carbon fiber in the transverse direction and the debonding at the interface between fiber and matrix has been evaluated quantitatively.