Analysis of Threaded Joint Mechanical Behavior in Barrel-Type MWD Instrument Under Make-up Torque

Abstract The normal operation of Measurement While Drilling (MWD) instruments is directly impacted by the strength of threaded joints. To investigate the mechanical behavior of threaded joints in Barrel-Type MWD instruments under make-up torque, theoretical analysis is conducted on the load distribution and axial preload force of threaded joints under make-up torque. Based on a typical MWD Instrument, considering the asymmetry of the threads and helix angle, a three-dimensional finite element model of the threaded joint is established. The mechanical behavior of threaded joints under make-up torque is simulated and analyzed using torque loading method. The results indicate that, under make-up torque load, the von-Mises stress distribution on each thread crest of the threaded joint is uneven. The von-Mises stress on the effective engaged threads from the large end to the small end of the threaded joint shows a gradually decreasing trend. During the make-up preloading process of the MWD instrument, excessive make-up torque may lead to the occurrence of thread joint fracture under external load during normal operation. The research findings contribute to a deeper understanding of the mechanical behavior of threaded joints in Barrel-Type MWD instruments under make-up torque load, providing valuable insights for the design and application of threaded joints in Barrel-Type MWD instruments.