Material and Manufacturing Technologies:
Constitutive modeling for the Mullins effect with constant set and obliged anisotropy in particle-filled rubbers
In a new research study, a new constitutive model is proposed that merges the micro-sphere model with the network alteration theory.
Rubber industry plays an important role in different application fields and particle-filled rubbers with reinforced mechanical properties are very necessary. The stress softening during cyclic loading, known as the Mullins effect, are obvious in filled rubbers. The Mullins softening can impel constant set and anisotropy. It is critical to understand these phenomena well. In a new research study, a new constitutive model is proposed that merges the micro-sphere model with the network alteration theory. The physical mechanisms of the Mullins effect in particle-filled rubbers are analyzed elaborately and comprehensively to propose new directional damage equations for the network alteration parameters. Both the softening effects in stretched directions and the stiffening effects in contracted directions are taken into account in the modeling.
The theoretical results of the model are then applied to forecast the stress softening, the residual stretch and the induced anisotropy in different filled rubbers. In addition, the prediction effect of the current model is compared with those by applying two existing directional macromolecular models. The comparisons with other model predictions and with the experimental data are then analyzed intensively to reveal the underlying mechanisms of the Mullins effect in the different filled rubbers. The results show that the ability of the suggested model to quantitatively predict the Mullins effect with permanent set and induced anisotropy and to clearly reveal the major mechanisms of the Mullins effect for various filled rubbers.