Sheet metal forming processes change the material properties due to work hardening (or softening) in the thickness direction as well as throughout the entire part. At the same time, uneven thickness distribution, mostly thinning, occurs as the result of forming. This is true for all commonly used sheet metal forming processes including stamping (deep drawing), tube hydroforming, sheet hydroforming and super plastic forming. The effects from forming can sometimes strongly influence the structural performance.
Though the CAE analysts have been trying to consider forming effect in their models for performance simulations, there was no easy way to do it consistently and reliably. Some analysts have been trying to modify the initial gage or yield strength to compensate for the property change due to forming. Replace the model with the formed panel is not feasible due to the mesh density difference. While tools exist for simulating sheet metal forming processes and vehicle performance such as NCAP, software with built-in capability to integrate the forming results as the initial condition will be ideal. The most efficient way to carry forming information is through mapping on the fly in the initialization phase of the analysis.
Many cases have been studied. The correlation can be significantly improved in some cases when forming is integrated into the model. The strategy and algorithm of mapping were studied and presented in this paper. However, actual correlation study is not in the scope of this paper. The authors will also summarize the enhanced mapping capability built-into LS-DYNA as a result of a joint effort between GM and LSTC. New features have been implemented to enhance the usability of the built-in mapping feature.