A physics-based nonlocal theory for particle-reinforced polymer composites

How the nonlocal interaction effects of particle-reinforced polymer composites manifest themselves from their underlying microstructure is not fully understood, thus greatly limiting the ability to model their mechanical properties. This paper explores the nonlocal interaction mechanisms of particle-reinforced polymer composites and unveils that both the nonlocal interaction effects between particles and the nonlocal effects of natural discrete polymer chains play an important role in particle-reinforced polymer composites. Then, a physics-based nonlocal continuum theory capable of capturing these two complex nonlocal effects is proposed based on the Eshelby equivalent inclusion method, the Mori–Tanaka model, and the interpenetrating network model. The proposed physics-based nonlocal continuum theory provides a rigorous methodology for developing physically consistent nonlocal homogenization models of particle-reinforced polymer composites and their composite structures. The results show that the two nonlocal effects play a role in stiffness softening in the mechanical behavior of particle-reinforced polymer composites, and the nonlocal mechanical behavior predicted by the developed nonlocal homogenization model is highly consistent with the existing experimental data.