Ran Li

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.

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.

In this paper, the failure of the crosshead-cylinder hole tribo-pairs in a reciprocating pump is reported. The crank-connecting rod-crosshead mechanism was analyzed to obtain the velocity of the crosshead. The material, hardness, and roughness of the new crosshead and cylinder holes were determined. Macroscopic observations, material properties and roughness analyses, scanning electron microscopy (SEM) analyses, energy dispersive spectrometry (EDS) analyses, and lubricating oil quality analysis were conducted to clarify the potential reasons for the failure of the crosshead-cylinder hole tribo-pairs. Lubrication oil degradation is likely to cause the failure of the crosshead-cylinder hole tribo-pairs. The effects of the oil supply system design and surface roughness on the anti-wear behaviors of the crosshead-cylinder hole tribo-pairs are discussed.

Understanding the fatigue behavior of materials is essential for designing components capable of enduring prolonged use under varying stress conditions. This study investigates the high-cycle fatigue and fatigue crack growth characteristics of X17CrNi15-2 stainless steel. Very high-cycle fatigue (VHCF) and fatigue crack growth tests were conducted on conventional fatigue and compact tension (CT) specimens fabricated from X17CrNi15-2 stainless steel. The fatigue crack growth behavior of the CT specimens was analyzed using Paris’ law. A revised version of Paris’ law was suggested based on the fatigue crack growth rate plotted against the stress intensity factor range, expanding on prior research utilizing three-point single-edge notch bend specimens. Scanning electron microscopy (SEM) was employed to examine the fracture mechanisms of both fatigue specimen types. The results indicated that the fatigue specimens failed in the VHCF regime under stress amplitudes ranging from 100 to 450 MPa. A power law correlation between stress amplitude and fatigue life was established, with material constants of 7670.3954 and −0.1663. These findings offer valuable insights into the material’s performance and are crucial for enhancing its suitability in engineering applications where high-cycle fatigue is a critical factor.

Laser powder bed fusion (LPBF) can fabricate hydraulic components with significant weight reduction, and in this study, small punch tests (SPTs) evaluated the tensile and fracture properties of four stainless steels (30Cr13, 316L, 15-5PH, 17-4PH), alongside metallographic, scanning electron microscope (SEM), and Electron Backscatter Diffraction (EBSD) analyses which examined their fracture modes, grain orientation, phase distribution, and grain boundary distribution. The tensile property results showed ductility rankings as 316L > 17-4PH > 15-5PH > 30Cr13, with correlations between R_p0.2 and R_m from SPT and uniaxial tensile tests for all four, while high-magnification SEM fractographs revealed ductile dimples on 15-5PH, 17-4PH, and 316L SPT specimens versus distinct cleavage fracture in 30Cr13. EBSD analysis indicated austenite content order as 316L > 17-4PH > 30Cr13 > 15-5PH, grain size order as 316L > 17-4PH > 15-5PH > 30Cr13, and high-angle grain boundaries ranking as 15-5PH > 30Cr13 > 17-4PH > 316L; additionally, notched SPT specimens inspected per EN 10371 for fracture toughness showed J-integral (J_IC) values in the order 316L > 17-4PH > 15-5PH > 30Cr13, consistent with ductility and grain size results.

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.

Reciprocating piston pump is an important power equipment in coal mine production, so the research on condition monitoring and fault diagnosis of reciprocating piston pump is of great significance. It is challenging to extract fault information from monitoring data due to the complex underground environment and serious noise. The existing methods have the problems of insensitive feature extraction and low diagnostic accuracy. Based on this, a new fault diagnosis method for reciprocating piston pumps based on feature fusion of convolutional neural network (CNN) and transformer encoder is proposed. In this method, a multi-scale CNN encoder and transformer encoder are used to extract local and global features of signals in parallel, and a multi-scale convolution module is used to improve the diversity of local features. At the same time, before using the transformer encoder to extract global features, patch segmentation of monitoring signals is carried out in combination with the phase of the reciprocating piston pump crankshaft to reduce the influence of data randomness on global features and improve the interpretability of global features. In addition, a feature fusion module is constructed to realize the interaction and fusion of local and global features and improve the comprehensive characterization ability of the device state. The proposed method is applied to the fault diagnosis task of reciprocating piston pump. The experimental results show that the proposed method achieves a diagnostic accuracy of 99.145% ± 0.1576%, demonstrating its excellent performance. This accuracy rate is significantly higher than that of other existing methods, indicating that the proposed method can more accurately diagnose the faults of reciprocating piston pumps.

With the increase in power and flow of emulsion pumps, pump valves are more likely to be damaged during long working hours, Therefore, it is important to ensure the reliability of pump valves at all stages. However, there are still some problems that need to be solved urgently. For example, whether the actual dynamic characteristics of the valve are consistent with the simulation results, and whether the simulation can replace experiments to provide a reference for the design improvement of the valve. At the same time, what is the failure mechanism of the valve, and what methods can be used to find the early failure of the valve. Therefore, the dynamic impact contact characteristics and fault diagnosis of valves of reciprocating piston pumps were investigated both experimentally and numerically. They were analyzed using AMESim simulation and U-Adolph theory, respectively, to predict the dynamic characteristics of the valve. The effect of spring stiffness on the dynamic characteristics of the valve was also investigated. The numerical analysis and analytical results are in good agreement with the experimental results, which provide an important reference for the development of new horizontal five-cylinder single-acting reciprocating pumps. In addition, finite element analysis was used to study the impact contact characteristics of the discharge valve closing under different valve diameters. The failure mechanism of the pump and valve was revealed, a fault diagnosis method was proposed, and the effectiveness of the method is verified by experiment.

In order to explore the tribological behavior of slipper/eccentric cam tribopairs under different lubrication conditions at power ends of water hydraulic radial piston pumps, friction-wear tests were carried out. It is found that tribopairs under water-based lubrication exhibited better...

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.