Creep-Fatigue Relationship in Polymer: Molecular Dynamics Simulations Approach

摘要

The creep-tensile fatigue relationship is investigated using MD simulations for amorphous polyethylene, by stepwise increasing the R-ratio from 0.3 for fatigue to an R-ratio = 1 for creep. The simulations can produce similar behavior as observed in experiments, for instances strain-softening behavior and hysteresis loops in the stress-strain curves. The simulations predict the molecular mechanisms of creep and fatigue are the same. Fatigue and creep cause significant changes of the van der Waals and dihedral potential energies. These changes are caused by movements of the polymer chains, creating more un-twisted dihedral angles and the unfolding of polymer chains along the loading direction.