Asymptotic Solution Of The Moisture Content InResin Matrix Composites Under CyclicEnvironmental Conditions

Abstract

One of the most important issues in the use of resin matrix composite materials in the industrial structures, especially in aeronautical structures, is the behaviour of the material due to moisture sorption through long years of service under cyclic environmental conditions. Tliis moisture diffusion yields an important influence on their durability and weakens their mechanical properties. In previous studies, we proposed and assessed quick solutions to determine the moisture content in the core after long term service, approximate bounds for the fluctuating part in the boundary layer of the plate, and the edge effect extent. In order to complete the quick determination of the moisture concentration, we propose in this paper new asymptotic solutions to determine the transient moisture content in the core of the plate versus time. All these solutions give a new perspective for the design of composite structures with the possibility to obtain quickly these hygroscopic parameters which are essential to determine mechanical properties of composite materials. Several examples are presented to assess the validity of our method and to demonstrate its high efficiency compared to the classical step-by-step integration. Transactions on Engineering Sciences vol 21, © 1998 WIT Press, www.witpress.com, ISSN 1743-3533