Temperature-dependent modelling of a HNBR O-ring seal above and below the glass transition temperature

Abstract

Sealing products can undergo many different atmospheric conditions and hence large variations in the in-service temperatures. These products, typically made of elastomer, are known to have heat sensitive mechanical characteristics. Since the reliability of sealing systems can be affected by cyclic temperature conditions, it is essential to predict seal performances depending on the temperature in order to prevent the occurrence of interfacial leaks. The aim of the present study is to simulate the thermo-mechanical behavior of a HNBR O-ring seal during a temperature cycle ranging from room temperature to low temperatures down to −34 °C. The main objective is to present the construction and the thermal dependency of a hyperelasto-visco-hysteresis (HVH) model so as to be able to predict the mechanical behavior of the elastomer in function of temperature. This phenomenological model is designed in the form of a combination of hyperelastic, viscoelastic and elasto-hysteretic stress contributions. The relevant parameters are identified using a material database based on the results of classical homogeneous isothermal relaxation tests and anisothermal relaxation tests. The predictions of the HVH model obtained shows good agreement with the experimental contact force during a 20% squeezed O-ring test under cyclic thermal loading below the glass transition temperature.