Influence of the filler properties on the mechanical response of silica filled natural rubber

The general frame of this study is the lifetime prediction of a structure made of silica-filled rubber. Namely, we aim at comparing the mechanical response of the natural rubber materials with the silica fillers nature mainly distinguished by their specific areas. The morphology and the complex microstructure of the precipitated silica make difficult their incorporation in the rubber matrix. Various types of mechanical tests show complex behavior including hyperelasticity, viscoelasticity, volume change. The specific treatment of the experimental results were performed in such a way that viscosity and volume change are neglected. This allows us to focus on the identification of the hyperelastic behavior of both materials. A phenomenological approach based on the polynomial Rivlin law has been selected. The material parameters are determined by optimization methods implemented in a finite element (FE) thanks to uniaxial tensile tests. A critical discussion about the optimized set of parameters will be done dealing with the existence of negative coefficients.