Development of a stress-state-dependent failure model of S355 steel for thin-walled tubes subjected to cantilever bending

The paper presents the development of a failure model dedicated to the simulation of cantilever bending of thin-walled tubes. The primary task was preceded by the development of a S355 structural steel material model with piecewise linear hardening curve and its validation based on the results of a radial crush test. The cantilever bending of smooth tubes and tubes with a plastic hinge initiator was subsequently conducted, and the results obtained were used to evaluate the failure models considered. At the same time, the effect of the number of failed integration points prior to element erosion on the response of failure model was investigated. The proposed approach, in which fracture occurs after reaching a triaxiality-dependent failure criterion in approximately half of the integration points through the element’s thickness, proved to be qualitatively and quantitatively superior to other models, as it accurately reflected the experimental results for both smooth and indented tubes. The paper concludes with the application of the developed failure model to simulate the performance of a post-type crash cushion. The predicted fracture location and pattern demonstrate high consistency with observations from an equivalent crash test, indicating that the proposed approach can be effectively applied to modeling bending-dominated problems in thin-walled structures made of ductile materials.