On the collapse of dented tubes under combined bending and internal pressure

The tube denting, pressurization, and bending to collapse have been simulated using solid finite element models. In addition to proper modeling the elastic-plastic behavior of the material, the model includes measured yield anisotropies, residual stresses, and wall eccentricity. The model reproduced quite well all aspects of the observed behavior including denting, bending and the ensuing collapse of the dented section, resulting in an inward kink with outward protrusions on either side. All predicted collapse curvatures were slightly lower than measured values. The cause of this discrepancy was traced to several small misalignments of the experimental dents, each of which tends to delay collapse somewhat.