Surface texture and titanium nitride (TiN) coating have been established as effective methods for enhancing the tribological property of mechanical friction pairs. This study aims to investigate the tribological performance of dimple-textured surfaces with TiN coating under oil-lubricated conditions using a pin-on-disc wear experiment. Four types of pin samples with various end surfaces were designed, including bare rod samples, TiN-coated samples, textured samples, and TiN-coated/textured samples. The surface texture consists of a series of cylindrical micro-dimples with a diameter of 150 μm and a depth of 40 μm fabricated on the end surface of the pin. TiN coating treatment on the textured surface of the end face was performed by vacuum sputtering coating equipment. The study focuses on measuring and comparatively analyzing the friction coefficient, wear morphology, and binding force of the pin-disc friction pairs among the experiments. Compared with bare rod samples, TiN-coated/textured samples will reduce the friction coefficient (COF) of the pin-on-disc friction pair by at least 20% under oil-lubricated conditions in a 50 N normal contact load. The results indicate that the synergistic effect of dimple surface texture and TiN coating optimizes friction performance and reduces wear, highlighting the novelty of this study. Furthermore, the study identifies the hydrodynamic lubrication effect of the surface morphology formed by the dimple surface texture as a key factor in improving lubrication performance and reducing friction. Additionally, the dimple surface texture enables the mitigation of third body wear due to the wear debris storage function of the micro-dimples. This research provides valuable insights for the design and fabrication of mechanical friction pairs with high wear resistance under oil-lubricated conditions.

Objectives: The aim of the present work was to comparatively investigate the generation and characteristics of fretting and sliding wear debris produced by CuNiAl against 42CrMo4. Methods: Tribological tests were conducted employing a self-developed tribometer. Most experimental conditions were set the same except for the amplitudes and number of cycles. Morphological, chemical, microstructural and dimensional features of the worn area and debris were investigated using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and a laser particle sizer. Outcomes: Not only wear scar profiles but also the wear debris color, distribution and generated amount under fretting and sliding wear modes were quite different, which can be attributed to the significant difference in wear mechanisms. Particle size analysis indicates that the fretting debris has a smaller size distribution range; the biggest detected fretting and sliding wear debris sizes were 141 μm and 355 μm, respectively. Both fretting and sliding debris are mainly composed of copper and its oxides, but the former shows a higher oxidation degree.

Nowadays, the electro-hydraulic actuator plays an important role in some modern tactical missiles. High power, great robustness and high tracking precision are the most significant demands for the missile actuator. Therefore an advanced method of active disturbance rejection control (ADRC) is presented aiming at the dynamics of the system are highly nonlinear and have large extent of model uncertainties, such as tremendous changes in load. Firstly, a novel ADRC controller is designed for estimating and compensating disturbance based on the mathematical model of missile electro-hydraulic actuator. Then, the influence of rudder load on the system performance is analyzed in this paper. Simulation results show that the ADRC control approach can decrease the tracking error and enhance the robustness of missile electro-hydraulic actuator system when the rudder load changed tremendously. But the phenomenon of Anti-Control has disadvantageous effect on the transition period of actuator loop and evenly causes the system divergence.

The influences of interactions between copper plate and nano-water droplets on wettability with different solid–liquid potential parameters were studied, and the spread of droplets was compared and analyzed using the molecular dynamics method. The diameter of droplet spreading and the amount of water molecules adsorbed on the copper gradually increased with the potential parameters, whereas the absolute potential energy value between copper and water also increased. Negative potential energy represents the attraction force between solid atoms and liquid molecules, and the attraction grows stronger with the large absolute value of negative potential energy. The heat transfer performance of the wettability surface can be explained by analyzing the force of solid and liquid from the perspective of energy. These results are of great significance for establishing the wettability model of a smooth plate correctly and the design and manufacture of a special functional surface.

The operational stability and vibration performance of large-scale ventilation fans used in forestry storage facilities are critical for ensuring the safety and environmental control of timber and wood-based materials. To effectively reduce vibration levels and mitigate resonance risks, this study proposes a structural parameter optimization method that explicitly considers substructure uncertainty. By establishing an interval uncertainty optimization model, critical substructures and key structural parameters affecting natural frequencies were systematically identified. Structural parameters were optimized using response surface methodology to maximize the separation between the fan’s natural frequencies and its operating frequency, thereby reducing the likelihood of resonance. Experimental results validated a substantial reduction in vibration levels, confirming the method’s effectiveness in enhancing operational stability and prolonging the service life of these large-scale ventilation systems. This approach provides valuable insights and practical guidance for vibration control and reliability improvement of mechanical equipment in forestry storage and environmental control systems

Texture and coating technology can significantly improve the tribological properties of mechanical components. In this study, the lubricating and wear properties of the reticular surface texture under the action of TiN were studied. Lubrication and wear experiments at different speeds were conducted using a UMT-3 wear and friction testing machine. Using Fluent fluid simulation, the bearing capacity of the oil film was obtained, and the lubrication performance of the texture was verified. The results showed that the simulation experiment and the lubrication experiment were consistent to a certain extent. For the groove width and angle parameters studied in this paper, optimal parameters existed to achieve the maximum bearing capacity, 1.27 N. Due to the high hardness and low elastic modulus of the TiN coating, the coated reticular texture was more wear-resistant, and it achieved the minimum wear volume 1.148 × 10⁻⁶ mm³ from the grinding stainless-steel matrix. The effect of the fluid dynamic pressure, wear debris collection, and lubricating oil storage were the main reasons for the increase in load-carrying capacity and the decrease in wear with the coated reticular texture.