Indentation of tubes under combined loading

A theoretical analysis is presented of the problem of large plastic deformations of tubes subjected to combined loading in the form of lateral indentation, bending moment and axial force. A model of the shell is proposed, describing local damage of tubes subjected to large strain, rotation and shape distortion. The model is effectively decoupling the 2-D problem into a set of 1-D problems. The force-deflection characteristics of tubes were shown to depend strongly on the magnitude of the bending moment and/or axial force applied to the tube ends. The calculations revealed that the resistance of the tube to lateral indentation and thereby the energy that the tube can absorb sharply diminishes as the direction of axial force changes from pre-tension to pre-compression. The present results were shown to give good correlation with existing experimental data.