It has been recently observed that addition and dispersion of a few weight percentof nanoscale particles in polymer matrix composites have reduced brittleness andmicrocracking of polymer matrices and improve their strain to failure and fracturetoughness without incurring weight penalty. This paper aims at using moleculardynamics to study length scale effects at the nanoscale, identifying the existence of alower bound on flaw-size that marks the transition from brittle to ductile failure innanocomposites, thereby causing deviations from linear elastic fracture mechanics(LEFM) predictions. Crack-tip bond-order based prediction of critical far-field stressand stress intensity factor is also addressed in this work. The MD predictions areobserved to deviate from LEFM predictions below a certain length-scale. This studyon nanoscale fracture of crystalline (graphene) lays the foundations for the futureatomistic predictions of fracture in amorphous (polymer) nanocomposite systems.
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