Experimental and Numerical Study on LCF Crack Propagation of Coiled Tubing Steel

Authors

  • Jijia ZHONG Southwest Petroleum University; Sichuan Aerospace Zhongtian Power Equipment Co. Ltd
  • Guanghui ZHAO School of Mechanical Engineering, Southwest Petroleum University
  • Litong WANG Southwest Petroleum University
  • Yi HE Southwest Petroleum University
  • Sihai HU Southwest Petroleum University

DOI:

https://doi.org/10.5755/j02.mech.31056

Keywords:

coiled tubing (CT), low-cycle fatigue (LCF), crack growth rate, experimental study, J-integral.

Abstract

Coiled tubing (CT) is a joint-less long oil pipe that is wound around a reel and can be run and pulled continuously. Due to the particularity of the operating process, low-cycle fatigue (LCF) failure of the CT constitutes the main production cost. Aiming at the characteristics of small diameter and thin wall of CT, a single-edge-notched (SEN) arc specimen was designed and machined. LCF tests were conducted with force-controlled mode. Cyclic softening of the CT steel was presented and crack growing rates were measured. Meanwhile, finite element simulation was carried out to obtain the relationships among J-integral, crack size and load. Based on the experimental and numerical results, the speed of the LCF crack growth of the CT steel is expressed as an explicit function of the J-integral. It provides a basis for predicting the LCF life of the CT under working conditions from the perspective of crack propagation.

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Published

2022-10-21

Issue

Vol. 28 No. 5 (2022)

Section

MECHANICS OF SOLID BODIES

License

The copyright for the articles in this journal is retained by the author(s) with the first publication right granted to the journal. The journal is licensed under the Creative Commons Attribution License 4.0 (CC BY 4.0).