EFFECTS OF MOISTURE ON GLASS FIBER REINFORCED COMPOSITES

摘要

Glass fiber-reinforced composites (GFRP) have come to be used for primary structural parts such as the main rotor system of helicopters, and these parts are sometimes very thick. Polymer matrix composites are generally degraded by moisture absorption. A study has been conducted in order to improve the reliability and to optimize the design criteria in the use of GFRP. Tensile tests using a new structural-grade glass fiber (T-glass) were conducted after long exposure up to 120 days at atmospheric humidity (between 30 and 95 percent R.H.). The relation between the moisture and degradation of GFRP is discussed. Then the moisture distribution of thick GFRP in two immersion conditions was analyzed. One was a predicted long-term standard atmospheric condition and the other was conventional accelerated absorption test condition. Finally, it was found that the conventional accelerated absorption test method was too severe to evaluate the mechanical degradation of thick GFRP. A new test method is, therefore, proposed.