Original paper(Vol.45 No.5 pp.490)

Effects of matrix resin and fiber content on behavior of fatigue crack propagation in continuous-fiber-mat reinforced CP-resin composites

Iwamoto Masaharu; Kurashiki Ken; Araki Shigetoshi

Abstract:The purpose of the present work is to investigate the effects of matrix resin and fiber content on the behavior of fatigue crack propagation in continuous-glass-fiber-mat reinforced CP-resin composites. For this purpose, ductile matrix resin and brittle one are used. These two kinds of resins have the characteristic that the elastic modulus and tensile strength are nearly the same with each other, while the elongation is different. The composite specimens are made of these resins and continuous glass fiber mat of 20 wt.% and 60 wt.% fiber contents. The fatigue crack propagation test was conducted by using the tapered DCB specimens to control the stress intensity factor range, DK, during the test. The results obtained are as follows;
(1) The relation between the crack propagation rate, da/dN, and DK for all the present materials is shown by a straight line in logarithmic representation. (2) For the composites of 20 wt.% fiber content, the da/dN of the ductile matrix composite is lower than that of the brittle matrix one at the same DK. (3) For the composites with either one of the matrix resins, the DK value of the 20 wt.% fiber content composites is about 40 percent less than that of 60 wt.% at the same da/dN.

Key Words:polysteramide resin, continuous strand mat, fatigue, crack propagation, GFRP, delta K-controlled test, TDCB specimen