Towards the digital twin of a multi-stage forming process for metallic sheets

Abstract

International audienceDigital twins are a major constituent of advanced and smart manufacturing, to decrease the time tomarket, improve process efficiency and reduce waste production. There seems to be a common unders-tanding on the different levels of integration of the communication between the physical object and thedigital object, i.e., digital model, shadow and twin, with the digital twin being the stage when it sendsactions to perform in real-time to the physical object, for an efficient execution of the process. In thefield of material forming, digital models are well established nowadays, based on finite element simula-tions and physics-based constitutive equations to represent the material mechanical behavior, althoughin general the high calculation time prevents any real-time interaction. The aim of this study is to designfirst a digital shadow of a progressive multi-step sheet forming process, aiming at a digital twin in asecond step. The target is to adjust the process parameters according to the mechanical properties va-riations. The physical process involves cutting of rectangular blanks, U-draw bending, springback anda last calibration stage to compensate for the springback. To provide a reliable representation of themechanical behavior under complex stress states and large strains, distortional hardening is consideredalong with isotropic hardening. An analysis of variations of the mechanical properties of DP600 steelwas performed, to generate several material parameter sets. Based on finite element simulations of themulti-step process, a sensitivity analysis of the forming process outputs to the mechanical propertiesvariations is carried out. The results highlight the operating principle of the digital twin, stressing outthe required sensors