Molecular simulation guided constitutive modeling of filled rubber: Bridging structural parameters to constitutive equations

A molecular simulation guided parametric modeling method of constitutive equations has attracted attention, which directly computes the physics-based structural parameters in molecular models without fitting stress-strain data. Using this method, we make a first attempt at constitutive relations of filled rubber by calculating amplification factors related to stress and strain distributions. The force field of the filled cis-1,4-polyisoprene (PI) rubber molecular model is obtained by the Boltzmann inversion method, which guarantees the accuracy of the structural parameters. The microstructural parameters and constitutive equations of the cross-linked, uncross-linked and the filled models are studied respectively. The calculated stress-strain curve of the cross-linked model is in the best agreement with the experimental one, while the curves of other models are in good agreement at small strain and have a certain degree of consistency at large strain.