Multiscale modeling of the viscoelastic properties of CNT/polymer nanocomposites, using complex and time-dependent homogenizations

• Published in: Computational materials science 2018-02, Vol.142, p.395-409
• Main Authors: Shajari, Ali R., Ghajar, Rahmatollah, Shokrieh, Mahmood M.
• Format: Article
• Language: English
• Subjects: CNT reinforced polymer composite; Equivalent fiber; Equivalent inclusion; Multiscale model; Viscoelastic properties
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2017.10.006

[Display omitted] •A combined molecular structural/micromechanics multiscale model is developed.•In model I, the CNT and its interface are modeled by an equivalent fiber.•In model II, the embedded CNT in the matrix is modeled by an equivalent inclusion.•For microscale homogenization, the Mori-Tanaka method is used for both models.•A time-recursive iterative solution is applied for time-dependent micromechanics. In the present research, a combined molecular structural/micromechanics multiscale model was developed to predict the viscoelastic properties of carbon nanotube (CNT) reinforced polymer composites. At the nanoscale, transversely isotropic time-dependent properties of an embedded CNT in the matrix were obtained using a finite element (FE) based molecular structural model in which the beam, solid continuum and nonlinear spring elements were used for carbon bonds, surrounding matrix and van der Waals interactions, respectively. To homogenize the heterogeneous nature of nanocomposites at microscale, Mori-Tanaka method was applied and the corresponding overall viscoelastic properties were obtained. To this end, nano-structural equivalent structures (equivalent fiber (EF) and equivalent inclusion (EI)) were developed to consider the nano-structural interactions. To apply micromechanics formulations, using the Fourier transform viscoelastic properties were transformed to frequency domain in algebraic forms. Additionally, an iterative-based solution for the Mori-Tanaka method was introduced and performed to use the time-dependent properties in the micromechanics model. The overall time dependent, storage and loss moduli of nanocomposites obtained by different methods were presented. A comparison of the creep response of the two models with available experimental data reveals that the EI model can predict more realistic properties compared to those obtained by the EF model.