Xiangyu Geng

Lightweight design is crucial for reducing inertial forces and vibrations in high-power-density reciprocating plunger pumps (RPPs). However, the tribological compatibility of lightweight alloys for crosshead–liner tribo-pairs is not well understood. This study systematically evaluates the friction and wear behaviors of six lightweight materials (TC4, TC4 (MAO), TC11, TC18, ZL108, and AlSi10Mg) sliding against HT250 gray cast iron under different lubrication conditions using an SRV IV tribometer. The results show that the lubrication regime significantly affects tribological performance. Water lubrication led to severe abrasive wear and high friction coefficients (0.75–0.91), while oil lubrication reduced friction to around 0.20 and promoted the formation of protective boundary films rich in P, S, and Zn. Material selection played a key role in wear mechanisms: aluminum alloys performed better under oil lubrication, whereas titanium alloys were more stable under water-lubricated conditions. MAO treatment on TC4 improved wear resistance, reducing the wear weight to less than 0.3 mg under oil lubrication by creating a strong ceramic oxide layer. Negative wear rates in lower specimens indicated material transfer from the upper specimen to the lower specimen. Based on performance metrics, the TC4-MAO/Shell 220 combination is recommended for lightweight crosshead applications. This study offers insights and guidelines for material selection to enhance the reliability and efficiency of future hydraulic equipment.

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.

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.