Fracture behavior of Lennard-Jones glasses

The fracture behavior of binary Lennard-Jones (LJ) glasses is studied by extensive molecular dynamics simulations. These LJ glasses represent a nonbond limit of polymer network glasses. We determine that the low strain behavior of the LJ and polymer glasses is similar. Two different LJ glasses are fractured under tensile strain without any preexisting crack. Void formation and resulting growth as strain increases is the mechanism through which the system fails. Void formation initiates at the yield strain of ${\varepsilon }_y\simeq 0.09,$ which is approximately the same strain at which the yielding behavior is first observed in cross-linked network models of polymer adhesives. The yield stress increased only by small amounts with increased strain rate and with increased system size (from $N=30\mathrm{}000$ atoms to $120000$ atoms). Within the ranges tested, the stress-strain behavior of these systems is independent of the temperature drop during quench and the initial molecular configuration.