Evaluation of longitudinal Young's modulus of unidirectional carbon fiber reinforced plastics

Abstract

The elastic modulus of unidirectional carbon fiber reinforced plastics (CFRP) was investigated by mechanical tests and analysis using finite element method (FEM). The mechanical tests are three points bending tests and tension tests. The analysis was examined by micro model and macro model. On the micro model, the 3-dimensional finite element method program created in consideration of the anisotropy of carbon fiber and the isotropy of matrix was applied to the hexagonal array model. On the macro model, the 2-dimensional finite element method program created in consideration of the anisotropy of CFRP was applied to the plane stress model using the triangle element. Consequently, it was found that the calculated data of the micro and macro model was larger than the experimental data. It was considered that the carbon fiber in the matrix was wound. Furthermore, the calculated data of the macro model in consideration of the angle θ of the direction of the carbon fiber was found to be in a reasonable agreement with the experimental data of the tension tests in case of θ = 0∼18° decided by the random number. The maximum of θ is considered to be small because that the Young's modulus of the interface layer is smaller than that of the matrix.