An Upper-Bound Solution for Tube Cropping

An upper-bound solution for the cropping of thin-walled tubes is developed, based on a plastic hinge approach, to predict the load-deflection behavior up to the point of shearing. A simple strain theory is used to estimate the deflection at the maximum cropping load. A deformation pattern (collapse mode) is proposed consisting of plastic hinges and then, for any given deflection, the associated plastic work is calculated. Subsequently, the cropping load is estimated by numerical differentiation with respect to the deflection. Comparisons are made with experiment.