The contact behavior of a stepseal affects its reliability and remaining life. In this study, experimental and numerical analyses were performed to investigate the contact behavior of a typical stepseal. Its dimensions and material properties were also tested. The Mooney–Rivlin hyperelastic model was used to fit the stress–strain data of the rubber. A static contact pressure of 105.1 MPa was obtained using the Fujifilm pressure measurement film. A finite element model of a stepseal with reasonable element sizes was established. A comparison between the experimental results and finite element (FE) predictions shows that the finite element method underpredicts the maximum static contact pressure and contact length. For the maximum contact pressure, the test results were approximately 30.4% higher than those of the FE predictions.

Small punch fatigue tests (SPFTs) were conducted on three high-strength stainless steels: X17CrNi15-2, 15-5PH, and PH13-8Mo. The SPFT valley displacement-versus-SPFT life curves for the three stainless steels exhibited three different stages. Power-law relationships were obtained to characterize the maximum forces with SPFT lives for different stainless steels. The fracture mechanisms of the tested SPFT specimens were characterized via scanning electron microscopy, which was dependent on the materials and applied loads. Finite element analyses were performed to obtain the equivalent local stresses and strains. A simplified critical plane-strain energy density (SED) criterion was used for the SPFT life assessment by correlating the FE-obtained strain energy density with the SPFT life. The SED values for the SPFT life were in the following order: PH13-8Mo > 15-5PH > X17CrNi15-2.

The dynamic sealing performance of Stepseal^® is vital to the reliability and remaining life of Stepseal. In this study, experimental and numerical investigations were performed for characterizing the dynamic sealing behavior of a typical Stepseal. A specific test rig was designed in order to experimentally obtain the dynamic friction force of the Stepseal, in accordance with the ISO7986 standard. A partial mixed-lubrication model, with the integration of inverse hydrodynamic lubrication and Greenwood–Williamson (G–W) surface contact model, was developed to numerically describe the dynamic sealing performance of the Stepseal. The effect of speeds and pressures on the predicted contact pressure as well as the film thickness of the Stepseals was discussed. A comparison between the experimental results and numerical predictions, in terms of the friction forces, shows that the partial mixed-lubrication model can provide reasonable accuracy for characterizing the dynamic sealing performance of the Stepseal.