The interest in accurate prediction of failure of sheet metals in the automotive industry has increased significantly over the last two decades. This paper aims to evaluate two failure prediction approaches implemented in the commercial Finite Element code AutoFormplus R7.04; (i) the standard Forming Limit Diagram (FLD), and (ii) the Non-linear Forming Limit Diagram. The evaluation will be testing the two approaches accuracy on predicting failure of both an AA6016 aluminium alloy and a CR440Y780T-DP dual-phase steel alloy specimen exposed to combined tension and bending. Based on the findings of this study, it is concluded that neither of the evaluated approaches is able to accurately predict failure in both cases presented. © Published under licence by IOP Publishing Ltd.

Ensuring process feasibility is a high priority in the automotive industry today. Within theCAE departments concerning the manufacturing of body components, one of the most important areas ofinterest is the accurate prediction of failure in components through Finite Element simulations. This paperinvestigates the possibility of introducing the component curvature as a parameter to improve failureprediction. Bending-under-tension specimens with different radii are used to create a Bending CorrectedForming Limit Surface (BC-FLS), and a test die developed at Volvo Cars, depicting production-like scenariosby exposing an AA6016 aluminium alloy blank to a stretch-bending condition with biaxial pre-stretching, isused to validate the proposed model in the commercial Finite Element code AutoFormTM R8. The findings ofthis paper showed that the proposed BC-FLS approach performed well in the failure prediction of the test diecompared to the already in AutoFormTM R8 implemented max failure approach.

An area in the automotive industry that receives a lot of attention today is the introduction of lighter and more advanced material grades in order to reduce carbon emissions, both during production and through reduced fuel consumption. As the complexity of the introduced materials and component geometries increases, so does the need for more complex failure prediction approaches. A proposed path-independent failure criterion, based on a transformation of the limit curve into an alternative evaluation space, is investigated. Initially, the yield criterion used for this transformation of the limit curve was investigated. Here it was determined that the criterion for the transformation could not be decoupled from the material model used for the simulation. Subsequently, the approach using the transformed limit curve was tested on an industrial case from Volvo Cars, but a successful failure prediction was not obtained. © 2022 The Author(s). Published by Trans Tech Publications Ltd, Switzerland.

As new and more advanced sheet metal materials are introduced to the market, more accurate techniques for determination of failure limits are needed. One area that needs attention is edge formability, where the ISO-16630 standardized Hole Expansion Test currently is used to express this through the Hole Expansion Ratio. Over the years, this standard has been criticized for producing a large scatter in repeated tests. This paper investigates a new setup for the Hole Expansion Test which introduces draw beads into the setup to ensure sufficient restraining of the specimen during the test in an effort to reduced the scatter. In total 62 tests of a DP800 steel alloy were executed, but a large scatter in the results were still seen. It was therefore concluded that a lack of restraining force in the Hole Expansion Test was not the primary cause of the reported scatter seen in other tests.