Optimisation des paramètres du procédé de pliage en tombé de bord par plan d'expériences numérique et méthode des surfaces de réponse

Abstract

Bending has significant importance in sheet metal product industry such as automotive security parts. The present work presents a general framework of numerical simulation of wiping die bending processes. A Computer Aided Design (CAD) for bending process using finite element method is presented which consists of metal forming operation characterised by complete material deformation. In this paper, we describe robust methods of predicting load bending evolution and stress distribution of specimens in 3D modelling subjected to bending deformation. The values are determined in a local frame according to elements deformation. A numerical approach of the problem requires a comprehensive finite element modelling due to the diversity of physical phenomena involved, such as friction effects, material and geometrical non-linearities, large plastic deformation and material failure. Lemaitre's material damage within the sheet was taken into account in the simulation during forming process. The interface contact law is defined by Coulomb's friction model and the elastoplastic constitutive laws are integrated by means of an incremental formulation which has been implemented in the finite element code ABAQUS. The influence of punch/die clearance and die shoulder radius are analysed. An algorithmic loop programmed in Script language of ABAQUS was retained to investigate the mechanical responses of the part for each case of parameters combination. The punch load and the distribution of stresses could be predicted in view of optimising the value of the main parameters of the process. An optimisation technique based on the use of Design Of Experiments (DOE) and Response Surface Methodology (RSM) is proposed in the work in order to minimise the tensile and compressive stresses found in the most damaged zone during the bending operation. Numerical results have shown the robustness of the proposed model and are discussed in more detail and enlightened by corresponding plots.