Effective elastic moduli of nonspherical particle-reinforced composites with inhomogeneous interphase considering graded evolutions of elastic modulus and porosity

Abstract

Recent experimental studies have found that interphase between particles and matrix possesses inhomogeneous configurations of elastic modulus and porosity. Such inhomogeneous properties of interphase play an important role in macroscopic mechanical properties of particle-reinforced composites (PRCs). In this work, a comprehensive micromechanical framework is devised to predict the elastic properties of PRCs containing spheroidal particles and their surrounding inhomogeneous interphase zones with the graded evolutions of elastic moduli and porosity. In the present framework, the elastic modulus gradient of interphase varies in terms of a power-law and its porosity gradient is characterized by virtue of a semi-empirical model originated from the test of cementitious composite experiments. The elastic properties of two-phase PRCs with aligned and randomly distributed spheroidal inclusions are first described through the double-inclusion model. The inhomogeneous properties of interphase are then incorporated into the prediction of the overall elastic modulus of PRCs by using the combination of the generalized self-consistent scheme with the double-inclusion model, which is essentially a general n-phase graded spheroid model. Comparison with experimental data indicates this proposed micromechanical framework is a reliable means to evaluate the elastic properties of PRCs. Furthermore, the predicted results elucidate the coupled effects of elasticity and porosity gradients in the interphase, spheroidal particle size and shape, and water–cement ratio have significantly impacts on the effective elastic modulus of PRCs, suggesting that the properties of such materials can be tailored via proper composite engineering and design.