Experimental and Numerical Evaluation of the Stress-strain Characteristic for Synthetic Rubber Spheres

The paper presents a parallel between the calculation of deformations for uniaxially compressed rubber spheres, by direct measurement on the experimental stand. Generalities about rubber, definition, properties, main characteristics and examples of use, are presented. An own experimental study is then presented to study the deformability of rubber spherical bodies and to analyze the deviations of rubber behavior from the Hertzian model. An experimental rig was designed for this. Its operation and the working method used, as well as the force-deformation characteristics for different experimental situations are presented, the compression of two or three rubber spheres, with three different ways of supporting them. Considering that a model that accurately describes the behavior of rubber is the Money-Rivlin model, which is characterized by two constants, C10 and C01, these constants were determined by a simple method, using the hardness of the material as a basic element hyperelastic, measured on the Shore A scale. After determining the material constants, the deformation value was determined by numerical modeling with the help of Ansys software. For validation, the experimental curve for the deformation of a rubber sphere on a plane and the numerical curve for the similar situation with the experimentally determined mechanical characteristics, were plotted on the same graph. Finally, the conclusions resulting from the conducted research are presented: - highlighting two ways of evaluating the deformation of rubber spheres experimentally and numerically, determining the Monney-Rivlin specific constants to the material through a simple, efficient and valid method.; - an elegant way to calculate deformations is to model the contact by axisymmetric finite elements, because it uses a minimum number of finite elements and saves significant resources; - both the calculation method and the experimental methods used are validated by a good correspondence between the experimental curve and numerical results.