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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 -
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 -
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 -
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 -
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 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 -
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 -
Influence of temperature on in-plane and out-of-plane mechanical behaviour of GFRP composite
(2018)Journal of Physics: Conference SeriesIn this work, the challenges in forming of glass-fibre reinforced PA6, from experimental material characterization and parameter identification to numerical modelling using Finite Element Analyses (FEA) is reviewed and results are presented. Mechanical in-plane behaviour is characterized by tensile and bias extension tests. Out-of-plane characteristics are determined using the cantilever test. The constitutive model is set-up using LS-DYNA™, ...Conference Paper -
A discussion of the associated flow rule based on the FAY model and Nakajima tests
(2018)Journal of Physics: Conference SeriesConstitutive models based on a non-associated flow rule (non-AFR) have received increased attention due to their flexibility in capturing laboratory experiments. On the other hand, the recently proposed Fourier Asymmetric Yield (FAY) model enables the definition of convex yield functions with arbitrary complexity, which can be used in conjunction to an associated flow rule and nevertheless accurately match experimental data. The present ...Conference Paper