Papers by Author: Yu Chun Kuang

Abstract: This paper analyzes several important issues on the drill string system dynamics model and its numerical algorithm. Firstly, it introduces the commonly used numerical methods and contact algorithms, and analyzes the advantages and disadvantages of each method in detail. Secondly, it analyzes the application of explicit and implicit methods for the current stress iteration algorithm, and specifies the implicit algorithm should be used in the research of drill string system dynamics. This paper focuses on the research of damping model and bit-rock interaction model, solves the damping effect based on the theory of ocean wave mechanics, and establishes a simplified bit-rock interaction model. Finally, a virtual numerical simulation example shows that the method used in this paper can analyze the dynamic of drill string used in the 1,000-meter complex well bore. The research result of this paper has certain guiding meanings on the analysis of working behavior of extra-long pipe string in the complex well bore by using numerical methods in the oil field.

Abstract: This paper develops a set of tri-cone bit CAD system based on UG platform relying on using parametric design idea; studies the systematic structure and development principle of the cone bit CAD system; molds the cone, tooth and tooth slot by using the basic theory of parametric design and feature modeling corresponding to the example, and realizes the assembly of cone and tooth and virtual assembly of three cones. This system interface is simple, intuitive, easy to operate, and has good human-computer interaction and scalability and portability. This paper provides a research base for the developing a more perfect tri-cone bit CAD system on UG.

Abstract: The behaviour of geologic material such as granite under impact loading is involved in the study of safety requirements of structures in extreme simulations such as earthquakes, accidental impacts or explosions. Based on incident pulse shaping design of quasi-brittle material for dynamic tests, experiments on granite under uniaxial and active confinement conditions are conducted with the split Hopkinson pressure bar(SHPB). By adding the soft material mass as the pulse shaper, the stress uniformity in the specimens before fracture is ensured and the fluctuation of test data due to incident stress pulse is avoid. The experimental results show that the compressive strength is increasing with the strain rate and the confined pressure. The fragments size decreases with the strain rate. The research method and conclusion could be used to analyze the dynamic behavior of the other brittle materials.

Abstract: Tensile strength is one of the most important mechanical properties of granite. It is a key parameter for strength design, safety analysis of granite structures. In the present paper, experimental investigation on static and dynamic splitting tensile behavior of granite is carried out with Brazilian disc (BD) test. The incident wave of SHPB for the dynamic BD test was designed with pulse shaper. The results show that the dynamic tensile strength of granite is heightened with increasing strain rate.