A numerical investigation of the continuous bending under tension test

In this paper the continuous bending under tension test is analyzed by numerical simulation. The ability of achieving high strains by combined stretching and bending is considered. This deformation mode has similarities with the deformation that takes place in incremental sheet forming (ISF) and may—at least partly—explain the high strains that are observed there. The sensitivity of the numerical model to mesh discretization is studied as well as the influence of different material models. An isotropic hardening material model and two mixed isotropic/kinematic hardening material models are used. The results for the three models are very similar, for the shape of the load curves, but not for the point of necking. A numerical analysis of the cyclic force–displacement curve of the CBT test is presented. This analysis is focused on the pattern of the cycle and the evolution of the cycle during the test. The loss of stability for inhomogeneous stress distributions is analyzed and the importance of bending in stabilizing the deformation under tension is demonstrated. Stability is lost if the complete cross section is in a state of tensile stress.