CONSTITUTIVE MODELLING OF SILICONE ADHESIVE CONSIDERING MULLINS EFFECT

Silicone adhesive has been widely used in assembly glass curtain walls. To achieve a reliable bonding system, an effective description of material behavior is required. However, commonly used phenomenological hyperelastic models have not considered the microstructure properties of materials and cannot describe the mechanisms of their mechanical behaviors, while the classical entropic hyperelastic models often do not consider the non-affine deformation, entanglement effect or other features of polymer network. The above deficiencies make it difficult for the existing models to effectively simulate the mechanical behavior of silicone adhesive, especially the significant Mullins effect under cyclic loading. For these reasons, in this paper, based on the non-affine network model and microsphere model of polymer chain distribution, we modified the macro-micro deformation transformation and the evolution of chain conformation to consider spatial distribution of polymer chains in finite directions. Based on the modified model, network alteration functions are proposed for crosslinked and entangled network respectively using network alteration theory. These functions describe the evolution of polymer network under cyclic loading to model Mullins effect. Considering the microstructure properties and deformation mechanisms of silicone adhesive, the modified non-affine network model can describe the characteristics of polymer network, including non-affine deformation, entanglement effect, finite chain extensibility and spatial chain distribution. The comparisons with the experimental data and other model results demonstrate the capability of the modified model to accurately predict the mechanical behavior of silicone adhesive under various loading conditions, as well as the permanent set and modulus degradation of Mullins effect, which shows good potential in engineering applications.