Long-Term Durability of Unidirectional CFRP Subjected to Tensile Loading

Abstract

In the present study, the tensile strength and its long-term durability is predicted by Simultaneous Fiber Failure (SFF) model which is presented by the authors (Koyanagi et al. Journal of Composite Materials 2009). The main aim of this research is to evaluate a durability at the elevated temperature condition beyond glass transition temperature (Tg) of constituent polymer material. Two types of specimens are examined in this study. The fiber strengths, interface strengths, and matrix strength are measured in order to predict the tensile strengths of two composite materials. For evaluation of long-term durability, time-temperature superposition principle is adopted considering previous results (Koyanagi et al. Mechanics of Time-Dependent Materials 2012). DMA tests are conducted for resin to evaluate time acceleration by elevated temperature (Arrhenius-type activation energy) and Tg. The predicted durability of two composites show rather good agreements with experimental results, qualitatively. Especially for quantitative comparison, the static strengths and long-term durability of two composites agree well with experimental results. This paper suggests that the durability of unidirectional CFRP can be estimated even beyond Tg. The detailed procedure of this estimation is described as follows.