Session W18 - Computer Simulation II.
ORAL session, Thursday morning, March 15
Room 308-308, Washington State Convention Center
The mechanical properties of polymer glasses up to and beyond the yield point are studied with molecular dynamics simulations. A simple bead-spring model is employed, in which entangled flexible polymer chains form an isotropic glassy state upon cooling from the melt. Uni-, bi- and triaxial stress states are imposed on the solid, thereby exploring the effect of stress mixity. The mechanical response of the material is monitored for a wide range of strain rates and temperatures below the glass transition temperature. The yield stress under uniaxial shear deformation may be described with conventional transition state (Eyring) theory. For biaxial loading, a generalized von Mises yield criterion applies. Triaxial stress states change the mode of failure from shear deformation to cavitation and subsequent craze formation. Simulation results are compared to existing models and typical experimental results.