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On the use of fixed point translations as input variable for digital twins in deep drawing compared to current methods
(2021)IOP Conference Series: Materials Science and EngineeringRecent work aims at the inverse parameter estimation in deep drawing using pretrained surrogate models for the detection of the current process, material or tool parameters. The use of the methodology requires the definition of state variables to describe the current process state. Whereas our recent work makes use of draw-ins and local blankholder forces, other approaches from the literature also use skid-lines measured after the deep ...Conference Paper -
A full-field optimization approach for iterative definition of yielding for non-quadratic and free shape yield models in plane strain
(2020)IOP Conference Series: Materials Science and EngineeringAn advanced strategy for iterative definition of initial yielding based on planar strain distribution is presented. It is shown that full-field DIC measurement of NTR5 samples provides information on initial yielding for plane strain. The interdependency of strain increment and yield locus under assumption of associated flow allows for definition of yield parameters using a non-linear optimization scheme with LS-OPT. Pivotal for research ...Conference Paper -
Crystal plasticity as complementary modelling technique for improved simulations results of anisotropic sheet metal behaviour in forming processes
(2020)IOP Conference Series: Materials Science and EngineeringThe accuracy of the simulation results in terms of metal sheet forming strongly depends on the capability of modelling the anisotropic material behaviour. In addition, predictive capabilities of the models are strongly influenced by the way how the constitutive model parameters are calibrated. Macroscopic models lean towards to become more complex in order to map the material behaviour more precisely. As consequence the amount and complexity ...Conference Paper -
On the sensitivity of the Mohr-Coulomb ductile fracture criterion in the mixed stress-strain space on varying hardening curve approximations
(2019)IOP Conference Series: Materials Science and EngineeringIn recent years the use of the Mohr-Coulomb type fracture criteria has become popular in ductile fracture prediction. In ductile fracture prediction, fracture criteria are often transformed into the mixed stress strain space formulation and applied to numerical simulations in this formulation. This paper will investigate the shape of the Mohr Coulomb fracture criterion in the mixed stress strain space as a function of the used hardening ...Conference Paper -
A failure model for non-proportional loading under plane stress condition based on GFLC in comparison to eMMFC and PEPS
(2018)IOP Conference Series: Materials Science and EngineeringA mathematical model is presented for a forming limit for non-proportional loading under plane stress condition. The model results in an approach to reduce the number of experiments needed for the Generalized Forming Limit Concept (GFLC) and presents a numerical approach to calculate the linearized FLC from real Nakajima measurements. The mathematical model has been analyzed in comparison to Polar Effective Plastic Strain (PEPS) diagram ...Conference Paper -
Analysis of yield locus description on springback behaviour of CR700Y980T-DP steel
(2018)IOP Conference Series: Materials Science and EngineeringTo precisely predict springback, the stress and strain state has to be described correctly during the forming process and after load removal. In this work, different yield locus descriptions are considered for springback prediction of a CR700Y980T-DP steel with a thickness of 1.5 mm. Experiments and Finite Element Analyses (FEA) with LS-DYNA of a U-bending validation tool were performed and springback predictions compared. In the FEA ...Conference Paper -
Implementation of a tribology-based process control system for deep drawing processes
(2018)IOP Conference Series: Materials Science and EngineeringModern deep drawn parts have complex designs and are driven to the limits of the material formability in order to reduce costs. This leads to small process windows and unstable forming processes with high scrap rates. Especially at the beginning of a batch, when the tools are warming up, high scrap rates can occur due to the changing friction behaviour of the system tool – lubricant – metal sheet. To make processes independent from user ...Conference Paper -
Considering fluctuations of material properties, stainless steel 1.4301, on manufacturability of kitchen sinks
(2018)IOP Conference Series: Materials Science and EngineeringIn production of deep drawn sheet metal parts, it is often challenging to achieve a robust process. Especially in the production of kitchen sinks made out of stainless steel, the fluctuation of the process and material properties often lead to robustness problems. Therefore, numerical simulations are used to detect critical regions. To keep a constant product quality, process control is realised based on metamodels, which are computed by ...Conference Paper -
Implementation of feedback control in kitchen sink production
(2018)IOP Conference Series: Materials Science and EngineeringThe quality of deep drawn parts is affected by many different influences. These can be separated into material related, temperature related and tool related influences. In the case of the stainless steel used in kitchen sink production, the temperature not only influences the friction but also the material properties. Therefore, a continuous monitoring and adjustment of the process is needed. The present paper shows a possibility of ...Conference Paper -
On the prediction of yield loci based on crystal plasticity models and the spectral solver framework
(2018)Journal of Physics: Conference SeriesPrediction of the yield loci based on crystal plasticity material models in combination with an efficient solver, the FFT-based spectral solver, is the main focus of this study. Results of the CP-based yield locus modeling are compared with the well-established macroscopic model YLD2000-2d for various materials; steel as well as aluminum alloys. For this purpose, uniaxial tensile tests in various directions as well as biaxial tests were ...Conference Paper