宇宙航空研究開発機構(Japan Aerospace Exploration Agency)先進複合材評価技術開発センター

Application field of carbon fiber reinforced polymeric matrix composites (CFRPs) is still limited due to their dimensional instability regardless of the facts that carbon fiber has excellent low coefficient of liner expansion and high mechanical performance. Antennas and mirrors used in the space for observations through infrared or visible ray are required of extremely high dimensional stability. Dominant factors affecting time-dependent deformation of CFRPs are moisture absorption, chemical reactions, creep, and relaxation of internal residual stress. Targeting future applications of CFRP to space mirrors, our group started to examine above factors separately and to develop simulation techniques for the timedependent dimensional stability of CFRP structures. In this study, geometrical variations with time of CFRP plates were measured under a humid environment and a vacuumed condition. We discussed the effects of the environments on the geometrical instabilities. Nevertheless symmetric properties of the laminated specimens, they showed unpredictable geometrical variation like asymmetry materials. This is expected to be caused by a distribution of fiber volume fraction in thickness direction at each specimen. Hence, we investigated the fiber volume fraction as a function of position in thickness direction. And then, a FEA considering the distribution of the fiber volume fraction is conducted and the analytical results showed good agreement with the experimental results.