Comparative study on the sealing performance of packer rubber based on elastic and hyperelastic analyses using various constitutive models

Abstract

Evaluation of the sealing performance of the packer rubber varies according to specific simulation models. This paper aims at revealing the difference between elastic and hyperelastic analyses using the finite element mothed (FEM). The study extracts the hyperelastic parameters of the neo-Hookean, the Mooney-Rivlin, and the Yeoh models from a uniaxial tensile test. Then, the setting process of a mechanical packer is simulated by elastic and hyperelastic calculations. We compare the deformed configuration and the contact stress given by these models. Our results show that the Yeoh model produces the minimum residual sum of squares (RSS) among the hyperelastic models for hydrogenated nitrile butadiene rubber (HNBR). The mooney-Rivlin model has a negative parameter, making the calculation unstable. The linear elastic model fails to simulate the setting process, while the neo-Hookean model overestimates the contact stress. Despite the similar stress distribution, the nonlinear elastic model provides a 17.8% higher contact stress on average than the Yeoh model. A parametric study based on the Yeoh model points out that the sub-thickness of the packer rubber needs an elaborate design. Reducing the sub-thickness could increase the contact stress but decrease the seal length in the force control mode. From an engineering perspective, this study demonstrates that it needs to pay more attention when selecting an appropriate material model and a sound analysis method to evaluate the sealing performance of an oil packer.