A New Computational Method for Prediction of Transient Hygroscopic Stresses during Moisture Desorption in Laminated Composite Plates with Different Degrees of Anisotropy

Abstract

A theoretical study is presented for predicting the hygrothermal behavior of laminated composite plates during moisture desorption. This investigation is aimed at overcoming the computational difficulties in the determination of transient hygroscopic stress distribution through laminated plates and in the evaluation of the effect of anisotropy on the evolution of such stresses. To calculate such stresses during desorption phase, we present a new method by which we are able to predict directly the evolution of transient hygroscopic stresses within laminated composite plates without the calculation of moisture concentrations as in the case of Benkeddad’s method in which we are obliged to determine the moisture distribution across the plate before the calculation of such stresses. This is very important and must be taken into account in the design of composite material, particularly aerospace structures for example, aircraft. The second part of this investigation is devoted to the analysis of the effect of anisotropy on the hygrothermal behavior of laminated plates during moisture desorption. The polar representation method of anisotropic properties is selected as a convenient tool for this study. By this method, the author is able to assess the anisotropy of composite laminated plates using the degree of anisotropy. Some stacking sequences with different in-plane degree of anisotropy were investigated in order to show the effect of anisotropy on the transverse hygroscopic stresses. Finally, the results of this paper can be used to guide the derivation of future by opening a way for the optimal design of composite structures submitted to a moist environment.