Simulation of cavitation in a glassy polymer at the atomic level

3 Simulation of cavitation in a glassy polymer at the atomic level 

The simulated dilatations involved increasing steps of imposed dilatation on the simulation cell. To permit a detailed understanding of the dilatational response of the polymer at the atomic level the entire volume of the simulation cell was tessellated into Voronoi polyhedra at each atomic site, permitting determination of strain-increment tensor elements dcy for each site from local displacement gradients by a technique described by Mott et al. (1992). Such increments of imposed dilatation at a level of 3 x 10 were applied 100 times to obtain total system dilatations of 0.3 (Mott et al. 1993b). For eaeh dilatation increment the atomic site strain-tensor increments de were obtained for each site n. The two invariants, de , the atomic site dilatation increment, and the work-equivalent shear-strain increment, dy , were obtained from the individual increments as 

For each external dilatation increment the system-wide strain-increment tensors 

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