Mechanisms during laser bending

In order to investigate the thermomechanical phenomena during the laser bending process, a simulation is performed. The governing thermoelastic-plastic equations are integrated by the finite element method. The results are related to predictions as given by the so-called temperature gradient mechanism (TGM), which is often used in the context of laser bending. It turns out that approximative identical temperature time cycles result in a plane and a prebended sheet in completely different forming behavior, whereby the forming behavior for the bended sheet depends on which side is laser treated. This means that a quantification of the extension and homogeneity of laser generated temperature field is insufficient for the prediction of forming behavior. The TGM model does not take into account the influence of the different stiffness of a plane or bended sheet on the stress and strain history in the laser treated zone. For this reason the TGM model can’t predict the different forming behavior of the plane and the bended sheet.