Three-dimensional evolution of mechanical percolation in nanocomposites with random microstructures

• Effective composite properties were calculated for simulated random microstructures.
• Property variations were used to track the evolution of mechanical percolation.
• The model captured pseudo-percolation effects from particle-interface structures.

One mechanism that is expected to play a large role in the enhanced properties of nanocomposites is the formation of percolated or connected microstructures. Traditional percolation models, well developed for modeling electrical conductivity, are largely empirical and have little foundation in mechanics. Analytic micromechanics models, without the ability to describe random microstructural arrangement do not capture effects associated with the evolution of a percolated microstructure. In this work, a unit cell micromechanics model is used to predict the effective composite properties of simulated random microstructures in particulate reinforced composites. Scale effects, which are present in nanocomposites, are introduced into the model through the inclusion of an interfacial region linked to the size of the reinforcing phase. By tracking and observing the variability in the predicted effective properties due to random microstructures, the onset and evolution of mechanical percolation and related microstructural events can be tracked.