Effect of transverse strains and angular distortions on the nanoscale elastic behavior of platelet nanocomposites

Abstract

In order to correctly predict the macroscale elastic behavior of nanocomposite macroscale structures, an accurate nanoscale model must be available for subsequent homogenization. In this work, we demonstrate that the accuracy of that nanoscale model greatly depends on the consideration of transverse strains and angular distortions, which are not frequently taken into account, but have a significant influence on the cohesive mechanisms at the nanofiller-matrix interface. We use a nanoscale cohesive model to qualitatively and quantitatively analyze the effect of transverse shear and angular distortion on the interfacial stress transfer mechanisms. While the effect of the transverse strain is less significant, results show that angular distortion greatly affects the interfacial damage pattern. It appears to shift the interfacial shear stress distribution to one of the interface ends, which consequently also modifies the interfacial longitudinal stress distribution and its mean value, resulting in reduced nanocomposite stiffnesses. The effect should be taken into account as shear and transverse strains may be present at the macroscale if, for instance, nanofiller misalignment or stress concentrators exist. We also provide design maps representing damage onset for different 2D multiaxial strain states in graphene-epoxy nanocomposites, so that the strain state limit can be inferred for the given nanocomposite properties. A substantial reduction in the allowable strains can be observed.