The use of Finite Element Simulation allows accurate predictions of stress and strain
distributions in complex stamped parts. The onset of necking is strongly dependent on the strain
paths imposed to the parts and therefore the prediction of localized necking can be a difficult task.
Numerical models of plastic instability have been used to predict such behavior and recent and more
accurate constitutive models have been applied in these calculations.
In many manufacturing areas such as automotive, aerospace, building, packaging and electronic
industries, the optimization of sheet metal processes, through the use of numerical simulations, has
become a key factor to a continuously increasing requirement for time and cost efficiency, for
quality improvement and materials saving.
This paper makes an analysis of the evolution of strain gradients in stamped parts. The combination
of Finite Element Analysis with a Plastic Instability Model, developed to predict localized necking
under complex strain paths, shows that it is possible to predict failure with precision. Several
constitutive laws are used and comparisons are made with experiments in stamped benchmark parts.
Considering non linear strain paths, as detected in stamped parts, more accurate failure predictions
are achieved. The work described in this paper shows the need to include a post processor analysis
of failure, capable of predicting the behavior of the material under non linear strain paths. Taking
this phenomenon into account, it is shown that it is possible to increase the accuracy of the onset of
localized necking prediction.
Finite element simulation and Experimental verification of Incremental Sheet metal Forming