Abstract:
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The automotive industry has increased significantly the use of advanced high strength
steels (AHSS) in many structural components of vehicles, with the aim to reduce weight and also increase
safety. The high resistance of these steels is accompanied by a decrease in formability, which makes
simulation a requirement to adequately foresee the formability of a stretch formed component. For sheet
metal forming, the conventional diagram based in strains, Forming Limit Diagrams (FLD), is often used as a
failure criterion, but this approach is not effective when working with AHSS, due to the bigger effect
produced by changes on strain paths than conventional steels. This work proposes the use a Forming Limit
Stress Diagram (FLSD) based on the main stresses acting on the material. These FLSD has been obtained by
the simulation of stretching test. To improve the results, the tensile test curve has been extended by using an
optical measuring system and a subsequent adjustment of the stress-strain curve for the material. Finally,
simulations and real parts behavior have been compared and the failure predictions models have been
discussed. |