Slawomir Blonski and Witold Brostow
Departments of Materials Science and Physics, University of North Texas, Denton, TX 76203-5308, USA

Josef Kubát
Department of Polymeric Materials, Chalmers University of Technology, S-412 96 Gothenburg, Sweden

ABSTRACT

Molecular-dynamics simulations of stress relaxation have been performed for metals and polymers. A method that employs coupling between the simulation cell and an applied stress as well as an external thermal bath has been used. Two-dimensional models of the materials are defined with interactions described by the Lennard-Jones (mie 6-12) and harmonic potentials. A special method is employed to generate chains in dense polymeric systems. In agreement with experiments, simulated stress-relaxation curves are similar for metals and polymers. At the same time, there exists an essential difference in the stress-strain behavior of the two kinds of simulated materials. During the relaxation, trajectories of the particles in different materials display a common feature:there exist domains in which movement of the particles is highly correlated. Thus, the simulation results support the cooperative theory of stree relaxation.

**Phys. Rev. B 1994, 49, 6494.