Behavior of St-37 tube profiles under three-point bending; experimentally and numerically

Thin-walled elements are widely used in load-bearing structures and crash-critical parts, as they exhibit high strength and have a high energy absorption capacity. They are manufactured from metallic materials due to the strength and energy absorption characteristics expected from these elements in the machinery industry, especially in the automotive sector, where they are widely used. Among the metallic materials, the steel class that gives the closest result to these expectations is preferred. Thin-walled elements are often subjected to bending loading in the structural and collision critical parts in which they are used. For this reason, in this thesis, the behavior of thin-walled St37 material under three-point bending loading was investigated experimentally and numerically with different process parameters and compared with each other. Accordingly, three different cross-section profiles and three different support spacing distances were used as process parameters. In addition, all processes were analyzed using the finite element method using Hill-48 and Barlat-89 plasticity models, and the predictive performance of plasticity models for the bending behavior of thin-walled structures was revealed. Force-stroke graphs, moment-angle graphs, energy values and equivalent stress distributions were obtained as a result of experimental studies and numerical analyzes carried out in the thesis study. The results obtained showed differences with the variation of the parameters. When the experimental results are examined, the increase in the support spacing distance for all three section profiles causes a decrease in the force values and an increase in the moment values. In addition, the energy values absorbed in all three cross-section profiles gave the maximum result in the span distance of 100 mm. When the numerical analysis results are examined, the experimental force values of the pipe section profile and the energy absorbed by the Barlat-89 and Hill-48 stress-based model converge. On the other hand, no plasticity model converged to the experimental results in square and rectangular section samples.