Scratch Modeling of Paint Coated Sheet Metal for Multi-Stage Deep Drawing Process

Abstract The scratch phenomenon of paint coated sheet metal in multi-stage deep drawing has been investigated. The tensile tests at a quasi-static strain rate of sheet metals coated with two different types of paint were conducted along the rolling, diagonal, and transverse directions of the sheet metal in order to consider strain hardening and anisotropy. It has been found that the types of paint are negligible for plasticity behavior. Finite element simulations of the multi-stage deep drawing process was performed using the obtained material properties and the simulation results were compared with the actual testing. Through the simulation results, three approaches, which include the contact pressure, the accumulated slip distance, and the accumulated friction work were implemented to investigate the scratch phenomenon and they were compared for the scratched and non-scratched regions. It was found that the accumulated slip distance at the scratched region was larger than that of the non-scratched region with a good correlation from experimental observation, whereas either the contact pressure or accumulated friction work approach did not predict the experiments. Therefore, it is concluded that the accumulated slip distance is a good method to identify the scratch on the paint coated sheet metal during deep drawing process.