A Study of a Rapid Moisture Absorption Technique for Composite Aircraft Structures
Shun-ichi BANDOH, Yutaka MOMOSE, Hirohito HIRA and Masaru ZAKO
Abstract:The strength of composite materials depends on absorbing moisture. The aircraft structural integrity should be demonstrated by considering every factor which degrade its strength. The composite aircraft structural components should be tested after moisture absorption equivalent to the component lifetime exposure. However, the thick laminate needs a long period to absorb moisture in a conventional manner, such as high temperature and 100% humidity but ambient pressure. Then the rapid moisture absorption technique has been studied using a pressure chamber. The purposes of this study are cutting the period for moisture absorption and adjusting the moisture distribution inside components so that much higher reliability of the aircraft, the cost reduction of development and weight reduction of the components will be obtained. Some moisture absorption tests have been carried out. From this study, following results were obtained. 1) Under some high pressure and temperature condition, moisture absorption speed can be accelerated. 2) New analytical method can be suggested. 3) By using this technique, the period for 20mm thick laminates can be reduced by a factor of 3.5 under a 20 year moisture absorption condition 4) The appropriate moisture distribution inside of the thick laminate can be obtained by this technique. Key Words:Composite materials, Aircraft structural integrity, Moisture absorption, Pressure chamber, Period for moisture absorption, Moisture distribution