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Meeting NUMIFORM 2019: The 13th International Conference on Numerical Methods in Industrial Forming Processes
Symposium S-01: Modeling of the Anisotropic Behavior in Plasticity
Presentation Title Measurement of Unloading Behavior of AHSS and Its Effect on the Springback Prediction in FEM Simulation
Author(s) Nobuyasu Noma, Taiki Maeda, Toshihiko Kuwabara, Tomoyuki Hakoyama
On-Site Speaker (Planned) Nobuyasu Noma
Abstract Scope The effect of unloading behavior of advanced high strength steel sheets on the accuracy of springback prediction is investigated. For enhancing the accuracy of springback prediction, cyclic tension-unloading tests for a large strain level over 0.1 are systematically performed for three dual phase steel sheets (DP590, DP780 and DP980) used for automotive body parts. Using a universal tensile testing machine, pre-strains in 0.005 increments up to a quarter of uniform elongation (UEL) strain and in 0.01 increments after that strain are applied to the test samples over a strain range of 0.1. The variation of the tangential slope of the stress-strain curve during each unloading process is measured and the variation of the Young’s modulus after pre-straining (apparent Young’s modulus) is determined. Unlike previous researches, the apparent Young’s modulus slightly increases after taking a minimum value. In addition, the effect of this behavior on the accuracy of springback prediction is investigated in detail for actual press-formed parts. It is revealed that the model considering the increasing behavior of the apparent Young’s modulus after taking a minimum value provides a good agreement with experiment. Therefore, we conclude that an accurate reproduction of unloading behavior is crucial for accurate springback prediction.
Proceedings Inclusion? Undecided


A Comparative Study between Elasto-plastic Self-consistent Crystal Plasticity and Anisotropic Yield Function with Distortional Hardening Formulations for Sheet Metal Forming
Accurate Modeling of Experimental Strain-hardening Characteristics for Series of High Strength Steel
An Anisotropic Yield Model Reduced From The Yld2004-18p Function For Metals With Gentle Anisotropy Under Triaxial Loading
An Application of Homogeneous Anisotropic Hardening Model to Earing Predictions of Pre-strained Material
An Experimental Study on Yield Surface Evolution of a Trip-assisted Steel
Applications of a Stress Invariants-based Yield Criterion to DP980 & QP980 Steels
Characterization of Anisotropic Yield Criteria Using an Indentation Based Technique for Steel Sheets
Comparison of Strain-path Indicators for Analysis of Processes in Sheet-bulk Metal Forming
Determination of Strain Dependent Anisotropy in Layer Compression Tests and Resulting Influence on the Yield Locus Modelling
Material Modeling and Forming Limit Analysis of 6016-T4 Aluminum Alloy Sheet
Measurement of Unloading Behavior of AHSS and Its Effect on the Springback Prediction in FEM Simulation
Modeling of Sheet Metal Forming Based on Implicit Embedding of the Elasto-plastic Self-consistent Formulation in Finite Elements: Application to Cup Drawing of AA6022-T4
Modeling of the Differential Hardening of Pure Titanium Sheet and Application to Hole Expansion Forming Simulation
Numerical Integration of Isotropic and Anisotropic Plasticity Models
Plastic Anisotropy from Single Crystal to Multi-phase Steels
Prestraining Effect on Failure Behavior in Hole-Expansion Test of AA6022-T4 Sheet
Rate-dependent Tension and Compression Hardening Behaviors of Ahss for Sheet Metal Forming Simulation
Springback Prediction in Roll Forming using Nonlinear Kinematic and Homogeneous Anisotropic Hardening Models
Study on Hot Deformation Behavior and Microstructure of 5CrNiMoV Steel using Constitutive Modeling and Processing Map
Theory and Application Study of Springback Prediction Accuracy for QP Steel with Different Material Hardening Models

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