Helical buckling of a thin rod with connectors constrained in a cylinder

• This paper provides an analytical model for describing the comprehensive helical buckling behaviors of a rod with connectors.
• Buckling solutions under no contact, point contact and wrap contact cases are obtained.
• The effects of connectors on contact length, bending stress and contact force are analyzed.

Kinds of tubular columns with connectors are widely used in petroleum exploration and development field. In previous research, tubular columns are usually treated as homogeneous thin elastic rods constrained in a cylinder and little attention has been paid to the effect of connectors.This paper builds an analytical model to describe the comprehensive helical buckling behaviors of a rod with connectors. The three-dimensional buckling problem is divided into two lateral buckling problems in two mutual-perpendicular planes and the buckling solutions are obtained by solving the two lateral buckling equations.There are three contact cases between the rod and the cylinder, namely the no contact, point contact and wrap contact. The deflection curves of a rod in three cases and critical conditions between different contact cases are calculated in this paper. The effects of connectors on the length of the contact portion, bending stress and contact force of the rod are analyzed. The results indicate that the critical axial compressions only depend on the ratio of rod/cylinder radial clearance to connector/cylinder radial clearance and the effect of connectors reaches the maximum value under the critical condition from the no contact case to the point contact case. The comparison between the buckling solutions with and without connectors shows that the effects of connectors cannot be ignored in buckling analyses.