Inelastic Behavior of Pipe Subjected to Steady Extension and Cyclic Bending

The inelastic behavior of a pipe subjected to steady axial force and cyclic bending moment, such as shakedown, plastic fatigue, ratcheting and plastic collapse, is studied. By using two parameters c and d, which indicate the elasto-plastic interfaces of beam cross section, the boundary curve equations between various types of inelastic behavior are derived. The results are suitable for beams of any shaped cross section with two orthogonal symmetric axes. Especially, the load regime diagram for a pipe is obtained, which indicates the elasto-plastic behavior of the pipe under given combination of axial load and cyclic bending moment intuitively.