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In order to solve the problem of bolt loosening and failure, based on self-developed aviation self-locking bolts, the influence of locking coating on locking performance of self-locking bolts was studied, and the locking effect of bolts with molybdenum disulfide（MoS2）, nylon 11（PA11） and polyvinyl chloride（PVC） coating materials was explored. Bolt connection locking mechanism are analyzed in this paper, by using the method of finite element simulation analysis and experimental verification, the air with the self-locking bolt lock the simulation and experimental research of the coating material selection, the mathematical model of the thread contour complete accurate set finite element meshing, boundary conditions, load simulation, experimental verification and test bench.The results show that the average locking torque of MoS2, PA11 and PVC is 1.06 N·m, 1.95 N·m and 2.18 N·m respectively in the finite element simulation. When PA11 is used as the coating, it is closer to the requirement that the maximum locking torque is less than or equal to 2.05 N·m in American standard IFI524. The bench test verifies that the average locking torque of the locking bolt with PA11 coating material is 1.82 N·m. Compared with the value of simulation analysis, it is within a reasonable fluctuation range, and PA11 as the coating material can meet the actual production requirements.

Graphene on a stainless steel substrate will appear as localized bulges, and these bulges will lead to large fluctuations in friction force, which is the key to influencing the lubrication efficiency of graphene. Here, the effect of normal load on the nanofriction behavior of the bulged graphene on a stainless steel substrate is investigated. In the normal load study interval from 20 to 110 nN, an increment of 10 nN of normal load can increase friction force the more the normal load increases, and the two are not linearly correlated. The friction force in the graphene bulge region consists of two parts: the first part originates from the interaction of the graphene material itself in contact with the tip, and the second part originates from the resistance due to the pile-up of graphene deformation in front of the tip. The nonlinear correlation between the normal load and friction force is mainly related to the pile-up effect of bulged graphene. In addition, the friction force increase due to the graphene bulge region needs to go through a process, which is divided into two stages. The first stage is the increase in friction force due to the tip starting to contact the bulged graphene and the contact area increasing. The second stage is the increase in friction force due to the graphene regulating its configuration and repeatedly interacting with the tip. The normal load is linearly related to the first stage but not linearly related to the second stage. The nonlinear correlation between the normal load and friction force is mainly related to the second stage of friction force rise. Therefore, the change of normal load affects the stacking effect and the ability to regulate the configuration of bulged graphene, which leads to a nonlinear increase of friction force. This contributes to the application of graphene for nanolubrication of stainless-steel components in MEMS. [ABSTRACT FROM AUTHOR]

Micro-milling technology is an efficient method for machining titanium alloy thin-walled micro parts. However, the machinability of thin-walled microstructures can be greatly affected by chatters due to their weak stiffness, especially in difficult-to-machine materials like titanium alloys. In order to obtain high-quality thin-walled micro parts, a chatter mitigation strategy is presented and its mechanism is analyzed in this paper. The titanium alloy workpiece is submerged into a kind of high-viscosity fluid, which can improve machining stability by increasing the damping of the micro-milling process. The stability lobe diagrams (SLD) are established, and the machinability is analyzed and compared under different machining conditions. The cutting force, surface roughness, micro-tool wear, and dimension accuracy of thin-walled micro parts are selected as the evaluation criteria for the machinability assessment. Well-designed micro-milling experiments are carried out under dry, lubrication, and chatter mitigation conditions using the same cutting process parameters. The results show that the use of cutting fluid can effectively improve machinability under stable cutting processes, but the effect of cutting fluid is weakened under chatter machining. The proposed chatter mitigation strategy can suppress regenerative chatter throughout the micro-milling process for thin-walled micro parts and improve their machinability comprehensively. [ABSTRACT FROM AUTHOR]

A large-aperture pulse-compression grating is one of the key components for laser-driven inertial confinement fusion, and is extremely vulnerable to being damaged by volatile organic contamination during operation. Plasma cleaning technology is a prospective method for removing organic deposits on the surface of optical components. Dibutyl phthalate, a commonly used sealing material, is used as the contamination source in this study, and the method of reactive molecular dynamics is used to simulate the plasma-based removal process of organic contaminants. The effects of key plasma cleaning parameters are investigated, including the interaction time, particle incident energy, and reactive species. Different mechanisms of nitrogen and oxygen plasma interactions were investigated. The effect of plasma on chemical bond fracture was analyzed, and the synergistic effect of physical and chemical influences was considered. The decomposition pathways and removal mechanism of organic contaminants under different incident reactive species are proposed at the atomic level. [ABSTRACT FROM AUTHOR]

Aerostatic spindles are commonly employed in ultra-precision machines. The aerostatic spindle, as a critical key component for the development of industrial ultra-precision grinding machines, requires an industrial feasible precision engineering approach to robust design and optimization in order to render the high-precision spindle system. This paper presents such an approach to the design and development of aerostatic spindles and the associated digital virtual spindle systems based on multiscale modelling and analysis. Multiscale modelling and analysis combined with the virtual spindle simulation are used as the kernel of the virtual spindle system, including innovative design on the spindle system structure, fluid dynamics modelling, drive and control system, and the integration of the spindle electromechanical system, which can be used to systematically model and simulate both the static and dynamic performances of the aerostatic spindle system. Experiments are carried out to evaluate and validate the above approach and the virtual spindle simulations, which can be further utilized for the development of next-generation high-precision aerostatic spindle systems. [ABSTRACT FROM AUTHOR]