Mechanical Properties and Failure of Aerospace-Grade Epoxy Resins from Reactive Molecular Dynamics Simulations with Nanoscale Defects

This study found that a scaled-down defect epoxy model with combined force fields with GAFF2 and Morse bond potential captured nonlinear brittle epoxy behavior including failure events by allowing covalent bond-breaking under deformation. We performed uniaxial tensile and shear testing, and epoxy brittle behavior became apparent by increasing amounts of defects. This computational methodology provides more physically realistic thermosetting models that can facilitate better description of epoxy behavior, especially brittle fracture, and improved quantitative prediction of mechanical properties. The computational efficiency is greater for large deformation simulations compared to the ReaxFF force field, which generally requires a lower time step of ∼0.1 fs.