Material Behavior Characterization via Multi-Directional Deformation of Sheet Metal: Session II
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Shaping and Forming Committee
Program Organizers: Daniel Coughlin, United States Steel Corp; Cody Miller, Los Alamos National Laboratory; Kester Clarke, Los Alamos National Laboratory; Piyush Upadhyay, Pacific Northwest National Laboratory; John Carsley, Novelis, Inc.
Monday 2:00 PM
March 20, 2023
Room: Aqua 309
Location: Hilton
Session Chair: Kester Clarke, Los Alamos National Laboratory; Piyush Upadhyay, Pacific Northwest National Laboratory
2:00 PM Invited
Predicting Strength and Ductility of Multi-directionally Deformed Steel Plate: a Coupled Distortional Hardening and Continuum Damage Mechanics: Myoung-Gyu Lee1; Seonghwan Choi1; Soo-Chang Kang2; 1Seoul National University; 2POSCO
Strength and ductility of steel plate formed by multi-axial bending process are predicted by advanced constitutive models implemented in finite element (FE) simulations. The constitutive model for simulating the complex deformation couples a distortional anisotropic hardening and continuum damage mechanics (CDM). In the anisotropic hardening model, the yield surface is distorted following non-proportional loading paths and it reproduces the Bauschinger effect and transient hardening behavior. Additionally, the concept of CDM is coupled to the hardening model to predict the flow stress covering from yielding to post-necking response. To identify the constitutive model parameters, tension-compression and two-step tension tests at various material orientations are conducted. The FE simulations for multi-axial bending process are performed, and the predicted yield strength, uniform elongation, and ultimate tensile strength are compared with experiments. The FE simulation with the developed coupled plasticity-damage model can predict the multi-directional bending deformation of steel plate within the reliable accuracy.
2:30 PM Invited
Simplifying Complex Loading for Training Advanced Constitutive Models: Treating Sheet Metal Like It’s Not 2D
: Zachary Brunson1; Aaron Stebner1; 1Georgia Institute of Technology
The advanced constitutive models of today require creative mechanical testing to identify a multitude of material coefficients describing anisotropy, asymmetry, and hardening behaviors, especially for sheet metals. Historically, multiaxial experiments such as cruciform and hydraulic bulge tests have been employed for this purpose despite added cost and time. Although simpler methods have been proposed for characterizing some of the required material coefficients, it is often still necessary for mechanicians to replace experimental data with micromechanical or computational models or to resort to assumptions of higher symmetry. Here, we propose a battery of simple, if geometrically creative, mechanical tests achievable with a standard axial test frame to quantify plastic anisotropy and asymmetry in sheet metals. We then compare the results of this collection of tests against a bulk material calibration of the same material achieved using a battery of standard mechanical tests.
3:00 PM
A Novel Anisotropic Continuum Damage Evolution Model Coupled with Anisotropic Hardening under Non-proportional Deformation Paths: Seonghwan Choi1; Soo-Chang Kang2; Myoung-Gyu Lee1; 1Seoul National University; 2Steel Solution Research Lab, POSCO
A new continuum damage model coupled with anisotropic hardening model is developed. In the continuum damage mechanics (CDM) scheme, micro voids and cracks in materials reduce actual load-carrying area, and the damage variable can be obtained by the ratio between reduced and apparent area. To be applied for characterizing complex post-necking behavior after non-proportional deformation, a new anisotropic damage evolution law coupled with homogeneous anisotropic hardening based on distortional yield surface (HAH) is proposed. In the coupled constitutive model, the damage evolution is derived from anisotropic dissipation potential function which provides the stress coupled anisotropic damage evolution. The model is implemented to the finite element software ABAQUS with a semi-explicit stress integration scheme. For the verification of the proposed model, tensile tests for pre-strained notched specimens with various specimen geometries are conducted. The predicted load-displacements give good agreements with the experimental results.
3:20 PM
Determination of Optimum Tension-compression Loops/Cycles for Estimating Yoshida-Uemori Constitutive Model Parameters for Advanced Lightweighting Materials: Dilip Banerjee1; William Luecke1; Mark Iadicola1; Evan Rust1; 1National Institute of Standards and Technology
Yoshida-Uemori (Y-U) combined isotropic-kinematic hardening constitutive models are widely used in modeling deformation behavior of advanced lightweighting materials during forming operations for producing automotive sheet metal components. This model can predict springback effect that occurs during shaping and forming operations, which is attributed to the Bauschinger effect. The model is described by a set of parameters, whose values can be obtained by combing uniaxial tension-compression test data with finite element modeling results along with an appropriate optimization approach. However, Y-U model parameter values can vary based on the selection of the order of deformation (e.g., tension-compression-tension (T-C-T), C-T-C etc.), maximum strain level in each cycle, and the number of cycles or loops in the tests. The present work describes an optimum approach for estimating these parameters by conducting numerical experiments on collected T-C stress-strain data of several alloys by varying the order of deformation, strain levels, and number of loops.
3:40 PM Break
4:00 PM Invited
Characterization of Commercially Pure Titanium Twinning under Proportional Loading Paths: Jinjin Ha1; Abrar Ebrahim1; Jinjae Kim1; Brad Kinsey1; 1University of New Hampshire
Twinning of a commercially pure titanium (grade 1) under proportional biaxial stress paths is investigated using a custom designed cruciform specimen. The material is first tested under uniaxial tension in three orientations with respect to the rolling direction, i.e., aligned, transverse, and at 45°, and under equibiaxial tension to characterize the elasto-plastic behavior and to measure the twinning fraction. The experiments are conducted at three temperatures, i.e., 20°, 0°, and -10° C, to affect the twinning behavior. These experiments are used in a finite element simulation of the cruciform testing, including a User Material Subroutine for Abaqus/Standard to account for the twinning, in order to determine the displacement boundary conditions of each arm in order to produce proportional stress paths in the central gauge section. The identified, non-linear displacement paths are applied in the cruciform experiments to assess the twinning in the given stress states and validate the numerical simulations.
4:30 PM
Anisotropic Behaviour and Deformation Mechanism of Ti407 Sheets with Reduced Al Content: Saeed Tamimi1; Giri Sivaswamy1; Tabassam Yasmeen1; Salah Rahimi1; 1AFRC- University of Strathclyde
Ti407 is a newly developed Titanium alloy with low Al content. This work aims to investigate the deformation mechanism of Ti407 sheets under tensile along various sample orientations. To that end, in-situ tensile loading in an SEM was conducted on Ti407-sheet along with various directions to rolling direction (RD). Also, the microstructure evolution of the sample after different levels of deformation was measured using EBSD. The results indicate that the mechanical properties of this alloy are highly anisotropic and the deformation mechanism depends on the loading direction to RD. Microstructure analysis indicated that the initial material contains macro-zones parallel with the rolling plane. Results suggested that the dominant deformation mechanism in the 0RD sample is slip systems whereas a significant number of {11-22}<-1-123> twins have been developed in the 90RD sample to accommodate plastic deformation. The nucleation of twining was taken place at a strain of 0.08, within the micro-zones.