Some Key Issues in Multi-Scale Modeling of Thermoset Nanocomposites/Composites

Lacy, T., Gwaltney, S. R., Pittman, C., Toghiani, H., Jang, C., Nouranian, S., & Yu, J. (2011). Some Key Issues in Multi-Scale Modeling of Thermoset Nanocomposites/Composites. In S. M. Arnold, T. Wong (Eds.), Tools, Models, Databases, and Simulation Tools Developed and Needed to Realize the Vision of Integrated Computational Materials Engineering. Materials Park, OH: ASM International.

Key issues in the development of a multi-scale modeling strategy for thermoset composites and nanocomposites are addressed, with a focus on vinyl ester resins reinforced with vapor-grown carbon nanofibers. Integrated molecular dynamics (MD), computational micromechanics, and global finite element simulations are proposed to determine composite material behavior from the molecular to global structural scales. Novel MD calculations were performed to assess the potential for the formation of a distinct interphase region at the nanofiber/resin interface. Based upon the calculated equilibrium redistribution of liquid resin monomers, a thin styrene rich layer forms at the nanofiber surface that may dictate nanofiber/matrix interfacial properties after the resin is cured. An innovative crosslinking algorithm is being developed for vinyl esters that accounts for key aspects of free radical polymerization. After crosslinking, MD nanofiber pullout simulations will be performed to determine nanocomposite interphase properties and interfacial strengths for use in higher length scale models. Materials property data generated using MD simulations will feed directly into micromechanical calculations within the NASA MAC/GMC hierarchical multi-scale analysis framework. Progressive failure analyses will be performed that aim to establish structure-property relationships over a wide range of length scales, which account for the morphologies and geometries of real heterogeneous materials.