RESEARCH ON NONLINEAR VISCOELASTIC CONSTITUTIVE MODEL FOR UNCURED RUBBER

A novel characterization method for the mechanical behavior of uncured rubber is developed in this paper. To fully investigate the complex stress-strain behavior of the uncured rubber under different deformation patterns, three kinds of mechanical tests are designed, i.e., the uniaxial tensile test, the compression test and the shear test. It can be found that the stress-strain relationship of the uncured rubber is highly nonlinear and rate dependent. A generalized Maxwell model combined with the Yeoh strain energy function is proposed to describe the observed phenomena, and a good agreement between the simulation and test is obtained by curve fitting procedure. Furthermore, it is shown that the compatible constitutive model for the uncured rubber can be obtained only by using the experimental data in multiple kind of deformation, which is similar to vulcanized rubber. The experimental results and the established constitutive model are helpful for rubber engineers to understand the mechanical behavior of uncured rubber, and provide theoretical basis for rubber manufacturing process simulation.