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In order to further improve springback simulation results, AutoForm has devel-oped a new material model. This model enables the accurate description of material behavior at unloading, which is crucial for springback. It provides for both the softening of materials through the so-called Bauschinger effect, as well as the reduction of elasticity with increased strain. It is thus one of the most accurate material models currently available. An invaluable benefit is that it is completely compatible with current AutoForm material models, i.e. existing material data which is in widespread use can continue to be applied. With the addition of only four  new parameters, the effects of kinematic hardening are taken into consideration.
These parameters are not mathematically abstract values, but rather they have a comprehensible, clearly defined physical meaning. They can therefore simply be defined from, for example, tension-compression tests. On the other hand, should this work not be carried out, AutoForm offers default values per material group. This is possible since each of the parameters describes one independent physical effect. By using this kinematic hardening model, with practically no additional work, substantial improvements in accuracy can be achieved.
The result is reliable springback compensation of the die faces aided by simulation, which in general significantly reduces the number of tryout loops.
According to Dr. Waldemar Kubli, CEO of AutoForm Engineering, “The successful solution to springback problems requires not only an accurate spring back simulation. What is just as important is an integrated geometry compensator as well as a springback robustness assessment, since only stable processes can be compensated. AutoForm, with its products AutoForm-Compensator and AutoForm-Sigma, is the only integrated software available on the market which can offer all the essential components to successfully tackle challenging springback problems.” Interestingly, the introduction of new, state-of-the-art materials, such as ultra-high-strength steels and aluminum, which are increasingly being used to reduce the weight of vehicles, promotes the development of new material models that authentically describe their characteristics.
Parts stamped from these materials are more affected by springback than those made from mild steels. Springback modifies the final shape of the part and increases manufacturing costs. Predicting the final geometry of a part after springback and designing appropriate tooling to compensate for springback continues to pose practical problems in the manufacturing industry.
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