共振超音波スペクトロスコピー法および均質化法による炭素繊維の弾性特性評価

抄録

Composite materials are applied to aerospace structures because of its unique material properties. Since the kind of composite materials is inhomogeneous and anisotropic materials, the numerical analysis is used for evaluation of composite’s deformation behavior as well as damage progression. We used an unidirectional carbon fiber reinforced plastic (CFRP) specimen to measure the elastic constants of a CFRP laminate. Resonant ultrasound spectroscopy (RUS) method is an experimental/analytic technique to determine the elastic constants by measuring the natural frequencies of solid specimens. In this study, we measured the natural frequencies of the unidirectional CFRP specimen, and the elastic constants of that were investigated by using the finite element method and the optimization technique using the quasi-Newton method and the golden section method. Moreover, we estimated the elastic constants of the unidirectional CFRP by the homogenization method. We compared with the elastic constants obtained from the RUS method and the homogenization method to estimate the elastic constants of the carbon fiber in the unidirectional CFRP laminate. The elastic constants of the carbon fiber were overestimated compared with previously-reported values, because the anisotropic of the carbon fiber is not considered for the analysis of the natural frequencies of the specimen. It is considered that accurate estimation of the elastic constants of the carbon fiber is possible by accurate measurement of the natural frequencies in RUS method.