Buckling and postbuckling of segmented tubes under external pressure

The collapse by external pressure of a tube consisting of linked rigid segments with rotational resistance at the joints is studied. Nonlinear difference equations are formulated and solved. The buckling pressure increases with the number of segments and tends to that of a continuous ring. Postbuckling shapes depend heavily on the number of segments. The six-sided tube shows properties of catastrophe, hysteresis, and imperfection sensitivity.