Papers by Keyword: Contact Algorithm

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: In order to reveal the mechanism of deformation, disintegration and failure of shallow landslides of coal measure soil, through contact elastic-plastic FEM with shear strength reduction, the paper analyzes shallow landslides stability, calculates shallow landslides safety factors, and reveals the mechanism of deformation, disintegration and failure of shallow landslide of coal measure soil. The results are shown as follows: during shallow landslides of coal measure soil, the displacement of sliding mass sliding along sliding surface, the plastic strain of sliding mass and sliding mass sliding state along sliding surface don’t change simultaneously; adopting contact elastic-plastic FEM algorithm may better reflect the actual state and sliding process of shallow landslides of coal measure soil. It can help faithfully reflect real situations of shallow landslides like deformation, disintegration and failure of shallow landslide of coal measure soil, and it may afford one method that can be used as a reference of the stability analysis, accurate evaluation and forecast of this type of landslide.