セルロースナノファイバの添加による平織CFRP積層板の疲労寿命改善とそのメカニズム

抄録

The purpose of this study is to investigate the influence of the condition of the length of added Cellulose Nano Fibers (CNFs) on the fatigue life of plain woven CFRP plate. Four types of CNFs of which the length were different (about 6, 22, 68 and 126 µm), respectively, while the diameter of those were almost same, were prepared in order to investigate the effect of the fiber length on fatigue lives of the specimens of the CFRP plates under tension-tension cyclic fatigue loading. The apparent interfacial shear strengths between modified matrix and single carbon fiber or two carbon fibers were also evaluated. Changes of energy release rates for crack propagation around the interface between carbon fiber and epoxy resin were also simulated by using FEM. The experimental results showed that the fatigue life of CFRP was not improved by adding comparatively short CNF compared to that of original specimen. In contrast, when comparatively long CNFs were added into the matrix, fatigue lives of CFRPs were improved. The fractured surface observation suggested that interfacial adhesion strength between carbon fiber and epoxy resin was improved by adding comparatively long CNFs. The apparent interfacial shear strength between two carbon fibers and matrix was significantly improved when the well mechanical fiber bridging of CNFs occurred. The calculation results showed that the energy release rate due to de-bonding between carbon fiber and matrix was reduced when CNFs were mechanically bridged between two carbon fibers and matrix.