COMPARISON OF MICROMECHANICS METHODS FOR EFFECTIVE PROPERTIES OF MULTIPHASE VISCOELASTIC COMPOSITES

In this paper we examine the use of several popular micromechanics met hods for determination of effective composite properties when all phas es are viscoelastic. The elasticity-based Mori-Tanaka method and the f inite element method of cells are used, both via implementation of the elastic-viscoelastic correspondence principle. The finite element tec hnique considers two different periodic microstructures, square and he xagonal arrays, the results of which are compared with each other and the Mori-Tanaka predictions. The resultant effective properties for vi scoelastic composites are determined at a wide range of frequencies an d compared with transformed Hashin-Shtrikman bounds and Gibiansky-Milt on bounds. The Mori-Tanaka method in the transformed domain is by far the simplest to implement and it is shown that the method replicates t he major features of the storage and loss moduli of the composite, inc luding location and magnitude of the double loss peaks from the glass- rubber transition of each phase. It is also illustrated that the Mori- Tanaka method predicts a nearly log-linear relationship between result ant property and volume fraction at a given frequency. Limitations of the Mori-Tanaka method for viscoelastic composites are highlighted. (C ) 1998 Published by Elsevier Science Ltd. All rights reserved.