Research on Multi-Body Collision Dynamics of Ball Cage Flexible Drill Pipe Considering Borehole Curvature

A ball cage flexible drill pipe is a new type of ultra-short-radius drilling tool, which consists multiple joints hinged together. During the process, members will come into contact and wear, reduces efficiency load transfer. The multi-body collision dynamics model was proposed to study performance pipe. method considered influence borehole curvature. kinematic equations were established. Lankarani–Nikravesh collisional used characterize normal force, Coulomb friction describe tangential force. motion state simulated, force distribution during cycle analyzed, curvature radius on size studied. results show that running form shows “folded” shape compared with initial form; different in fluctuation; much larger than force; matching relationship between length derived, provides criteria for design ensure reliability large borehole; has an important transfer