ANALYSIS OF POST-BUCKLING OF LATERALLY CONSTRAINED LONG WEIGHTLESS TUBING SUBJECT TO AXIAL AND TORSIONAL LOADS

The equilibriUm equation for a long weightless buckled tubing in straight well under axial thrust and torsional moment is developed, The fourth-order strongly nonlinear ordinary differential equation is directly solved. The results show that the post-buckling configuration of the tubing under some idealized conditions is an exact belieal shape. An analytical solution for the relation between load and pitch has been determined. The influence of torsional loads on post-buckling of tubular in well bores, especially on the tubing spirals to the right or left, has been discussed. The degeneracy of the analytical results is coincident with those given by others using energy method.