Effect of temperature on the viscoelastic damage behaviour of nanoparticle/epoxy nanocomposites: Constitutive modelling and experimental validation
The accurate prediction of the complex material response of nanoparticle/epoxy nanocomposites for thermomechanical load cases is of great interest for engineering applications. In the present work, three main contributions with respect to multi-scale modelling of the viscoelastic damage behaviour of nanocomposites are presented. Firstly, a constitutive model for the viscoelastic damage behaviour at finite temperatures below the glass-transition temperature is proposed. The constitutive model captures the main characteristics of the material response including the non-linear hyperelasticity, softening behaviour and the effect of temperature. Secondly, the material model is calibrated using purely experimental results to evaluate the best capability of the model in reproducing the stress-strain response at different strain rates and temperatures. The calibrated model predicts the material behaviour across a range of nanoparticle weight fractions with good agreement with experimental results. Finally, a combined approach of experimental testing and molecular simulations is proposed to identify the parameters of the constitutive model. This study shows that the proposed simulation-based framework can be used to significantly reduce the number of experimental tests required for identification of material parameters without a significant loss of accuracy in the material response prediction. The predictive capability of the atomistically calibrated constitutive model is validated, with additional experimental results not used within the parameter identification, in terms of an accurate representation of the viscoelastic damage behaviour of nanoparticle/epoxy nanocomposites at finite temperatures. The present study underlines the capabilities of numerical molecular simulations intended for the characterisation of material properties with respect to physically based constitutive modelling and multi-scale approaches.