Xue Ling

The presence of particles leads to varying degrees of mass loss on a metal sealing surface, which severely affects the seal’s lifespan. Understanding the complex wear mechanism and optimizing the surface roughness morphology are particularly important in engineering. By characterizing the surface of the metal (SS 304) with different roughness parameters Ra, Rp, Rpk, Rpc and Rku, the variation mode of mass loss under abrasive wear conditions was revealed. Unlike traditional two-body wear, the involvement of abrasive particles significantly impacts surface Ra and other surface morphologies (asperity peak features). A contact model for metal rough surfaces, distinct from two-body contact, was established to clarify the changes in removal mechanisms. It was found that the change in the contact between the particle and the asperity peak led to a change in the mass loss and guided the appropriate metal roughness range: Ra 0.05 μm and Ra 0.6–0.8 μm. In addition, it was found that the removal of asperity peaks is holistic under low roughness, and only parts of asperity peaks are removed under high roughness. Notably, the metrological methods used in this study supplement existing roughness measurements. By exploring the complex removal mechanism of asperity peaks, micro-scale guidance for surface (texture) design, machining, and optimization is provided.

This study aims to achieve rapid drilling of life-support holes, regarding the optimization design of drill bits as the key, among which the simulation analysis of drill bit cutting teeth is an important technical means. Firstly, based on the rock mechanics test results in the study area combined with the corresponding logging information, the analysis and evaluation of the geological conditions in the study area were completed, a complete rock mechanics characteristic profile was established, and the drillability of the rock was calculated to be relatively good. Then, a numerical simulation of parallel cutting of rock with conical teeth was established by experimentally testing rock mechanics parameters and using the discrete element method (PFC2D). The simulation study of the drill bit cutting teeth was completed by parameter calibration, analysis of rock cutting morphology, analysis of the number of rock cutting cracks, and analysis of the specific work of rock cutting and breaking. It was determined that the optimal rock-entering angle of the drill bit cutting teeth in the Shouyang mining area is 14°. Finally, verified by field practice, the optimized drill bit has stable performance, strong cutting ability, and good wear resistance; the maximum instantaneous mechanical drilling speed reaches 58.14 m/h, and it shows a slightly worn state after continuously drilling 582 m in the stratum, meeting the requirements of one-trip drilling and hole formation for life-support holes. This research provides a scientific basis and practical techniques for the construction of life-support holes in the Shouyang mining area and under similar geological conditions. It can provide more effective emergency plans and rescue strategies for possible mine disasters in the future, which is crucial for improving the technical system of emergency rescue for mine accidents and enhancing the emergency rescue capability of surface drilling.

玻璃材料在核工业及航天航空、深空探测等领域发挥着重要的作用。然而，强辐照效应常常会导致玻璃材料变色、脆化、光学性能退化等，极大制约了其服役的可靠性和耐久性。设计抗辐照玻璃的核心便是深入理解其辐照损伤的宏微观物理过程，然而鲜有论文对其展开深入系统的总结和论述。本文从辐照效应的位移损伤和离子损伤原子级物理图像出发，阐述了玻璃中色心缺陷的形成机制，综述了损伤演化带来的光学及力热特性的变化，继而总结了不同损伤特征的实验监测方法，及宏微观损伤的多尺度计算方法和模型，旨在为抗辐照及耐辐照玻璃设计提供指导和依据。

In order to study the mechanism of crack propagation in rock cutting, experiments and discrete element numerical simulation of rock cutting at different depths were adopted in this paper. The rock fragmentation can be divided into mini-size fragmentation and normal-size fragmentation from a size viewpoint. The discrete element method (DEM) is used to further investigate the mechanism of normal size fragmentation at different depths and record the process of crack initiation and propagation. Additionally, the paper characterizes the process of crack initiation and examines the representative rock fragmentation. According to the mechanism of crack development, rock fragmentation can be divided into three categories: conventional failure, fracture failure, and damage failure. The fragmentation of three kinds of failure has one common point. To form semi-dislodged rock fragmentation, the macroscopic shear cracks are first formed. Subsequently, the tensile failure at weak places causes fragmentation ejection. Therefore, the mechanism of fragmentation generation in rock cutting is investigated in terms of crack initiation and extension. In this study, the fracture phenomenon of previous rock cutting experiments is reproduced by an experiment, and the failure process is analyzed in detail by the discrete element method, which reveals the essence of producing fragment phenomena and summarizes the fracture phenomenon and damage crack propagation mechanism in rock cutting.