A molecular-dynamics-based model for the rate- and crosslink-density-dependent deformation of silicone rubber

Abstract

Based on molecular dynamics simulations, a two-parameter hyperelastic constitutive model is proposed for silicone rubber and then extended for the rate- and crosslink-density-dependent uniaxial tensile behaviors. Taking into account the effects of crosslinking and entanglement, the total strain energy is decomposed into bonding and van der Waals terms. The simulation results show that the bonding term works at large deformation and prefers the quadratic term in Yeoh model. In contrast, the van der Waals term is found dominating at small deformation range and modeled through the homogenization of Lennard-Jones potentials. The effects of crosslink density and strain rate on model parameters are described by exponential and hyperbolic sine functions, respectively. Equipping parameters identified from molecular dynamics simulations, the model can efficiently describe the strain–stress relations in whole strain range and for all considered strain rates and crosslink densities. The proposed model and strategy should arise applications in description of complex behaviors of elastomers.