ONE STEP SPRINGBACK STRATEGIES IN SHEET METAL FORMING

Abstract. The near net shape characteristics of the formed component dictates the success of a sheet metal forming operation, for which one of the main sources of the lack of geometric and dimensional accuracy are the springback deviations. The application of numerical simulations to predict springback of sheet metal forming parts becomes more and more important, since these deviations often lead to tool modifications at the late stage of the development process. In this work the prediction of springback defects will be performed with CEMUC’s home code DD3IMP (contraction of ‘Deep Drawing 3-D IMPlicit code’) and the springback devoted code DD3OSS (contraction of ‘Deep Drawing 3-D One Step Springback’). This is a 3-D elastoplastic finite element code following a full implicit time integration scheme. This formulation allows to take into account large elastoplastic strains and rotations, and it has several constitutive laws and yielding criteria implemented. The Coulomb’ law models the frictional contact problem, which is treated with an augmented Lagrangian approach. The code considers the sheet as a three-dimensional domain described with solid finite elements. The use of an implicit method for the simulation of the deepdrawing process guarantees the structural balance at any given instant of the calculation, which includes the end of the forming process, before removing the tools. Three different numerical strategies for the springback simulation will be presented and discussed, including a numerical algorithm for the removing of all tools in a single step (DD3OSS). These numerical strategies will be used to perform the springback prediction of a complex geometry part.