Inextensional collapse of thin-walled tubes under axial compression

Inextensional collapse modes are presented for the axial compression of thin-walled tubes. Shortening is achieved by folding about fixed hinge lines to form a number of flat triangular planes. A new mechanism is propounded by which collapse proceeds progressively from one end of the tube, following the passage of a travelling hinge. Simple expressions are developed for mean collapse load and the energy absorbed during collapse of rigid-perfectly plastic tubes. Comparison of collapse modes and predicted loads with those obtained from experiments on rigid P.V.C. tubes of various thickness, diameter and length give encouraging agreement.