Strategy to prevent surface deflections for automotive sheet metal parts

A. Weinschenk, W. Volk

Research output: Contribution to journalConference articlepeer-review

2 Scopus citations


Surface deflections are undesirable in automotive outer panels because they disturb their visual appearance. As a consequence, the geometry of the deep drawing tool is manually adjusted during tryout until the produced parts do not display any surface deflections. The aim of this paper is to reduce this time-consuming and cost-intensive tryout by slightly changing the geometry of the tool in an early state of the product development process to lower the risk of surface deflections. Therefore, this paper shows the influence of geometrical parameters of the deep drawing tool on the occurrence of surface deflections. A multiple curved outer panel with a door handle depression is chosen for the investigation. Typically, so-called "teddy bear ears" occur around the depression. The sheet metal material AA6016 with a sheet thickness of 1.0 mm is used. Numerical simulations of the draw operation and springback are performed in AutoForm. An analysis of the curvature before and after springback is used to detect surface deflections. The influence of the stresses and curvatures on the appearance of surface deflections is analyzed. For the experimental validation, stoning is used to detect surface deflections on a physical part. A very good agreement between the numerical and experimental results was obtained. The results show that the existence of surface deflections strongly depends on the initial curvature of the part and the appearance depends on the distribution of minor stresses. It is possible to reduce the risk of surface deflections during the design phase by changing the geometry.

Original languageEnglish
Article number012058
JournalJournal of Physics: Conference Series
Issue number1
StatePublished - 27 Sep 2017
Event36th IDDRG Conference 2017: Materials Modelling and Testing for Sheet Metal Forming - Munich, Germany
Duration: 2 Jul 20176 Jul 2017


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