Multiscale analysis of large-strain deformation behaviour of random cross-linked elastomers

S Chaube and S Mishra and S Maiti and B Rai, MOLECULAR SIMULATION, 45, 111-119 (2019).

DOI: 10.1080/08927022.2018.1538559

The hyperelastic behaviour of elastomers is characterised by a complex and strongly non-linear response at large deformations, which leads to several modelling challenges. While the existing macroscopic-strain- invariants based models can qualitatively capture the trend of elastomer's deformation behaviour, incorporating network scale dynamics of polymeric chains becomes important in order to account for lower length-scale phenomena like chemical cross-linking and Langevin chain dynamics. In this work, the mechanical behaviour of SBR-1502 (unfilled) cross-linked elastomer has been simulated using a multiscale modelling approach. All atomistic MD simulations were performed to compute the equilibrium density, glass transition temperature and two lower length scale parameters - volumetric segment density of polymeric chains (N) and the average number of Kuhn segments between two cross-linking points (n). These parameters are fed into a constitutive modelling framework based on the 8-chain network concept of Arruda and Boyce to obtain the bulk equilibrium stress-strain response up to large values of strain. Hyperelastic stress-strain plots are obtained for uniaxial, biaxial and shear modes of deformation (up to similar to 750% strain) and limiting chain extensibility is investigated for the random network structure. Coupled model predictions are compared with available experimental data for SBR-1502 and the results are encouraging.

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