Micromechanical model of linear viscoelastic particle-reinforced composites with interphase.

• A constitutive model is proposed for viscoelastic particle-reinforced composites with interphase. • The predictability of the constitutive model promotes greatly the computational material design. • The constitutive model is comprehensively validated based on FE simulations. • The constitutive model is applied to identify the interphase properties. In this paper, a micromechanics-based constitutive model is proposed for linear viscoelastic particle-reinforced composites with interphase based on the theoretical homogenization framework in the time domain that we recently proposed for viscoelastic composites. All the composite's phases (i.e., the matrix, particle and interphase) are considered as linear viscoelastic materials, whose constitutive responses are governed by the general Maxwell model. The interphase with varying viscoelastic property is approximated by the multiple homogenized layers. The constitutive model of the composites is multiplicatively decomposed as two parts: (1) the effective relaxation function characterizes the time-dependent behaviors, and (2) the referred elastic part refers to the long-term responses. The classical composite-sphere model and three-phase model are extended to derive the variables involved in the constitutive model for the bulk and shear behaviors, respectively. The comprehensive numerical simulations, including the effects of the number of interphase layer, interphase thickness, particle content and loading condition, are carried out to validate the proposed constitutive model. The results reveal that the constitutive model can predict well the viscoelastic behaviors of the particle-reinforced composites with interphase. The validated constitutive model is then applied to identify the viscoelastic properties of the interphase by fitting the predictive results and the experimental data of the "overall" composites. The results show the good consistency for the interphase properties between the theoretical identification and the experimental observation. The discussion of the interphase percolation is then carried out, and the findings demonstrate again that the constitutive model can also give good predictions under the percolation situation. [ABSTRACT FROM AUTHOR]