Open AccessImproving the fatigue life of the tool-joint of drill pipes by optimizing the variable pitch of the box thread
Author(s) -
Volodymyr Kopei,
Oleh Onysko,
Anatolii Panchuk,
Андрій Петрович Джус,
V. R. Protsiuk
Publication year - 2021
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/1166/1/012017
Subject(s) - thread (computing) , computer science , finite element method , structural engineering , drill , modular design , rotational symmetry , parametric statistics , mechanical engineering , engineering , mathematics , geometry , statistics , operating system
The reliability of oil drill-strings largely depends on the reliability of tool-joints. It is known that the load along the tool-joint thread is distributed unevenly and it is possible to equalize it by applying a variable thread pitch of a pin or a box. The article describes the optimization method of the pitch change function along the box thread by maximizing of the minimum value of fatigue life in the pin roots. Additionally, the value of the contact pressure on the shoulder, which determines the screw make-up force, is taken into account. To implement the method, we used the Abaqus/CAE and fe-safe software, the parametric axisymmetric finite element model of the tool-joint developed by the authors and the procedures for local (BFGS method) and global (Differential Evolution method) optimization from the SciPy package.