Use of Response Surface Methodology for Prediction of Dent Resistance of Automotive Closure Panels

Prediction of dent resistance of automotive closure panels using Finite Element Analysis (FEA) has increased in popularity as an effective screening tool to determine the optimum combination of material properties and thickness for a given exposed panel application. The analysis process typically includes formability analysis, the results of which are mapped onto a structural model for analysis of dent resistance. Although this method is general, allowing for consideration of the entire panel assembly and boundary conditions, the approach can be very time consuming especially when evaluating several combinations of material grade and thicknesses. This paper presents an alternative approach for the prediction of dent resistance. Using a number of screening simulations the most influential variables affecting dent resistance were determined. A rectangular bi-curved plate was used to approximate the panel assembly. A Design of Experiments (DOE) approach was then used to vary the geometry, thickness, mechanical properties and stretch imparted during stamping. Denting FEA was conducted on these rectangular plates, followed by statistical analysis of the results of the denting FEA. Predictive models for dent resistance based on the statistical analysis were developed for several steel grades. Comparison of the model prediction to actual test results yielded excellent agreement.