  The tensile failure mechanism of Cu-Polyethylene-Cu (CPC) sandwich structure
was clarified by molecular dynamics (MD) simulations subjected to a uniaxial
tensile loading at microscopic scale. The sensitivity analysis of parameters
such as model size, relaxation time for equilibrium and initial velocity
distribution was carried out to verify the rationality of modeling. The
evolutions of stress-strain relationship and each potential energy component
were provided to describe the failure process of the structure. The peak of
non-bond energy shows a delay compared to the yield point in stress-strain
curve, which coincides with the local maximum point of the trans-fraction curve
of dihedral angles. After that, an inflexion appeared in the trans-fraction
curve indicates an energy transport process, which corresponds with the slope
change of the stress-strain curve. It is assumed that the dihedral distribution
plays a crucial role in the damage process of CPC structure. In addition, the
temperature field and the density profile were adopted to predict the position
of damage initiation, which was confirmed by the microstructure evolution. The
intrinsic thickness-dependence of CPC was explored by taking the coupling
effect of bridging and entanglement into account, which is in reverse
proportion with the yield strength of CPC.
