Transverse elastic modulus of carbon fibers measured by Raman spectroscopy

Raman spectroscopy was utilized to measure the transverse elastic modulus of carbon fibers in carbon-fiber reinforced plastics (CFRP). The PbO thin film was deposited on the surface of CFRP using physical vapor deposition as the pretreatment in order to measure strains of carbon fibers and epoxy matrix phases. Since the relation between Raman peak position of PbO thin films in wave number and tensile strain have already been examined by experiments, the transverse strain of carbon fibers was measured by Raman spectroscopy. The transverse strain of the carbon fibers was analyzed by finite element methods (FEM). The transverse modulus of the carbon fibers was determined by changing the modulus in FEM models to fit to the experimental result by Raman spectroscopy. This determined transverse modulus of carbon fibers is compared with those measured by nano-indentation and analyzed by 2 D and 3 D FEM models.