Analysis on Simulation and Experiment of the Drill-pipe Cross-section Deformation of Ultra-short Radius Radial System

摘要

The drill-pipe bending is a plastic with complex loads. The ratio for wall thickness to tube radius is out of the limitation of thin-walled shell. Contrary to general drill-pipe, the URRS is not elastic but plastic. Beam element cannot be used to URRS because the cross-section is changed during bending. Contrary to buckling theory, the sizes of two bending axes changed independently by using of 3D FEM simulation, and the secondary bending axis is based on loads degree whether it expands or contracts. The simulation extends the deformation theory of drill-pipe bending. The deformation of pipe cross-section is weakly dependent on the backpressure absolution, compared with the pressure difference between inner and outer. The FEM simulation well agrees with the experiments results.