Numerical investigation on the uniaxial compressive behaviour of an epoxy resin and a nanocomposite

The current work aims at exploring the relationship between complex failure behaviour and the presence of defects for RTM6 epoxy resin as well as hyperbranched polyester (HBP)/RTM6 nanocomposite under compressive loading. Numerical simulations were performed in LS-DYNA by means of a statistical approach that exploits different failure strains among elements. It allows a phenomenological description of the effect of defects and different stress triaxialities on the failure modes of polymer/nanocomposite materials. Additionally, a parameter describing defects, named defect severity, was added to the model in order to quantify and explore the effect of defects on the mechanical behaviour during the damage process. Both the generalized incremental stress-state dependent damage model (GISSMO) and Monte Carlo method were employed to simulate the effect of stress triaxiality and the spatial distribution of defects on the mechanical performances. The relationship between the defect severity and the failure modes (tensile-domain and shear-domain) was also discussed. Numerical results of neat RTM6 showed that the presence of a large number of defects can lead to more brittle (tensile-domain) failure, while numerical results of HBP/RTM6 nanocomposite presented that the addition of nanoparticles can compensate the negative effect of the existing defects in polymer materials under uniaxial compression, which provides a novel insight for potential applications of nanomaterials.