A micromechanical model for effective hygro-thermo-elastic properties of fiber reinforced composites with functionally graded interphases

In this paper, composites with multi-directional ellipsoidal fillers of arbitrary aspect ratio, and an interphase layer surrounding the filler, accommodating smoothly the differences in the filler and the matrix's properties, is taken into account. Each constituent of the fiber reinforced composite (FRC) is regarded to be isotropic and linear elastic, and the property of interphase is assumed to be of power-law variation across the thickness. Based on linear hygro-thermo-elastic theory and Elshelby's theory, a novel prediction scheme for effective stiffness, coefficient of thermal expansions (CTEs) and coefficient of moisture expansions (CMEs) of FRCs with functionally graded interphase (FGI) is proposed, in which the Mori-Tanaka method and piecewise method are used and novel analytical expressions for hygro-thermo-elastic of unidirectional FRCs are obtained, respectively; afterwards, a two-step homogenization technique is performed for the filler's distribution consideration. Numerical examples and analyses indicate that the effect of the thickness and mechanical properties of FGI on the overall properties of the FRC is substantial, especially for nano-filler reinforced composites; additionally, the filler content, the aspect ratio and orientation of inclusions have considerable influences on the overall properties of the hygro-thermo-elastic of FRCs. (C) 2020 Elsevier Inc. All rights reserved.

Automated summary

This paper presents a novel prediction scheme for effective stiffness, coefficient of thermal expansions (CTEs), and coefficient of moisture expansions (CMEs) of FRCs with functionally graded interphase (FGI). Multiple methods and analytical expressions were used, and a two-step homogenization technique was performed for filler distribution consideration in the analysis.