Prediction of Forming Limit of Dual-Phase 500 Steel Sheets Using the GTN Ductile Damage Model in an Innovative Hydraulic Bulging Test

JOM ◽  
2018 ◽  
Vol 70 (8) ◽  
pp. 1542-1547 ◽  
Author(s):  
Xiao-Lei Cui ◽  
W. W. Zhang ◽  
Zhi-Chao Zhang ◽  
Yi-Zhe Chen ◽  
Peng Lin ◽  
...  
Keyword(s):  
Damage Model ◽  
Ductile Damage ◽  
Forming Limit ◽  
Dual Phase ◽  
Steel Sheets ◽  
Bulging Test ◽  
Hydraulic Bulging

Application of Barlat Yld-96 Yield Criterion for Predicting Formability of Pre-Strained Dual Phase Steel Sheets

2016 ◽  
Author(s):  
Shamik Basak ◽  
Sushanta Kumar Panda
Keyword(s):  
Dual Phase Steel ◽  
Yield Criterion ◽  
Thin Sheet ◽  
Damage Model ◽  
Forming Limit Diagram ◽  
Plasticity Theory ◽  
Forming Limit ◽  
Dual Phase ◽  
Strain Paths ◽  
Anisotropy Coefficients

The selection of advanced material model considering the anisotropy mechanical properties of the thin sheet is vital in order to estimate stress based forming limit diagram (σ-FLD). In present study associative plasticity theory was applied indulging Barlat Yld-96 anisotropy yield function and the Swift hardening law was implemented for estimating the limiting stresses from the conventional strain FLD (ε-FLD) of an automotive grade dual phase steel DP600. Three different approaches were made to evaluate Yld-96 anisotropy coefficients using experimental results of stack compression and tensile tests. To impose complex strain path, two stage stretch forming processes were simulated in finite element solver LS-DYNA. After biaxial pre-straining, the sample geometries were varied to achieve different strain paths during the second stage of deformation. The results indicated that there was negligible difference in limiting stress estimated by Yld-96 plasticity theory when the anisotropy coefficients were calculated based on plastic strain at ultimate tensile strength compare to that by minimum plastic work method. It was concluded that the dynamic shift of ε-FLD could be restricted by σ-FLD estimated using Yld 96 plasticity theory, and hence it was proposed to be a suitable damage model to evaluate formability of pre-strained DP600 steels.

Numerical Prediction of Forming Limit in Hemispherical Punch Bulging by Lemaitre's Ductile Damage Model

2011 ◽  
Vol 110-116 ◽  
pp. 1437-1441 ◽  
Author(s):  
Farhad Haji Aboutalebi ◽  
Mehdi Nasresfahani
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Damage Mechanics ◽  
Thin Sheet ◽  
Damage Model ◽  
Ductile Damage ◽  
Forming Limit ◽  
St14 Steel ◽  
Hemispherical Punch

Prediction of sheet metal forming limits or analysis of forming failures is a very sensitive problem for design engineers of sheet forming industries. In this paper, first, damage behaviour of St14 steel (DIN 1623) is studied in order to be used in complex forming conditions with the goal of reducing the number of costly trials. Mechanical properties and Lemaitre's ductile damage parameters of the material are determined by using standard tensile and Vickers micro-hardness tests. A fully coupled elastic-plastic-damage model is developed and implemented into an explicit code. Using this model, damage propagation and crack initiation, and ductile fracture behaviour of hemispherical punch bulging process are predicted. The model can quickly predict both deformation and damage behaviour of the part because of using plane stress algorithm, which is valid for thin sheet metals. Experiments are also carried out to validate the results. Comparison of the numerical and experimental results shows good adaptation. Hence, it is concluded that finite element analysis in conjunction with continuum damage mechanics can be used as a reliable tool to predict ductile damage and forming limit in sheet metal forming processes.

Experiment and Meso-Damage Finite Element Analysis of Uniaxial Tension of Galvanized Steel Sheets

2012 ◽  
Vol 472-475 ◽  
pp. 547-555
Author(s):  
Zhi Ying Chen ◽  
Xiang Huai Dong
Keyword(s):  
Flow Stress ◽  
Uniaxial Tension ◽  
Volume Fraction ◽  
Simulation Analysis ◽  
Damage Model ◽  
Galvanized Steel ◽  
Forming Limit ◽  
Element Analysis ◽  
Steel Sheets ◽  
Whole Process

Uniaxial tension tests for galvanized steel sheets are performed. Fractured surfaces of the specimens are observed by means of the scanning electron microscope (SEM). It is confirmed that the specimens experience ductile fracture. Based on the Gurson meso-damage theory, Hill’48-GTN anisotropic damage model is presented, and used to analyze the uniaxial tension test. The true stress-strain curves are fitted by three kinds of main flow stress models. After comparing the fitting precisions, the Voce model is selected as the flow stress model for the simulation analysis. The simulation results show that the Hill’48-GTN model can be used to accurately predict the whole process of damage occurrence, evolution and fracture in tension, and void volume fraction can be taken as a forming limit parameter of sheet metal forming.

A Generalized Damage Model Accounting for Instability and Ductile Fracture for Sheet Metals

2014 ◽  
Vol 611-612 ◽  
pp. 106-110 ◽  
Author(s):  
Jun He Lian ◽  
Xiao Xu Jia ◽  
Sebastian Münstermann ◽  
Wolfgang Bleck
Keyword(s):  
Stress State ◽  
Ductile Fracture ◽  
Automotive Industry ◽  
Void Nucleation ◽  
Damage Model ◽  
High Stress ◽  
Forming Limit ◽  
Dual Phase ◽  
Sheet Metals ◽  
Hard Phase

With the requirement of vehicle performance and fuel economy, dual-phase (DP) steels as one of the advanced high stress steels (AHSS) are increasingly used in the automotive industry due to the excellent combination of the tensile strength and ductility. On a microscale the ductile fracture is governed by the void nucleation, growth and coalescence mechanism. In the dual-phase steels this damage mechanism exhibits a rather complex situation: voids are generated by the debonding of the hard phase from the matrix and the inner cracking of the hard phase besides by inclusions. On a macroscale fracture of these materials is observed in the automotive industry with the absence of strain localization or minimal post-necking deformation. Consequently the failure during the forming process is caused by a competitive or combined mechanism of internal damage evolution and metal instability. In this study, the target is to develop a simple and generalized model for metal forming processes accounting for instability, damage and ductile fracture. Theoretical predictions of metal instability by the Hill–Swift necking criterion and the modified maximum force criterion are considered. The damage model is developed by the combination of the prediction of metal instability and ductile fracture of sheet metals. The model is developed in 3D triaxial stress state and the accumulation of damage is stress state dependent. Furthermore, the influence of the hardening curve effected by damage on the forming limit curve is investigated.

Modeling of Solder Fatigue Failure due to Ductile Damage

2010 ◽  
Vol 26 (4) ◽  
pp. N23-N27 ◽  
Author(s):  
K. Aluru ◽  
F.-L. Wen ◽  
Y.-L. Shen
Keyword(s):  
Numerical Study ◽  
Fatigue Cracks ◽  
Damage Model ◽  
Quantitative Information ◽  
Ductile Damage ◽  
Element Analysis ◽  
Cyclic Shear ◽  
Rate Dependent ◽  
Solder Fatigue ◽  
Temporal And Spatial

ABSTRACTA numerical study is undertaken to simulate failure of solder joint caused by cyclic shear deformation. A progressive ductile damage model is incorporated into the rate-dependent elastic-viscoplastic finite element analysis, resulting in the capability of simulating damage evolution and eventual failure through crack formation. It is demonstrated that quantitative information of fatigue life, as well as the temporal and spatial evolution of fatigue cracks, can be explicitly obtained.

scholarly journals Forming limit diagram prediction of 6061 aluminum by GTN damage model

2018 ◽  
Vol 19 (2) ◽  
pp. 202 ◽  
Author(s):  
Rasoul Safdarian
Keyword(s):  
Damage Model ◽  
Forming Limit Diagram ◽  
Numerical Results ◽  
Experimental Results ◽  
Correct Selection ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Gtn Model ◽  
Gtn Damage Model

Forming limit diagram (FLD) is one of the formability criteria which is a plot of major strain versus minor strain. In the present study, Gurson-Tvergaard-Needleman (GTN) model is used for FLD prediction of aluminum alloy 6061. Whereas correct selection of GTN parameters’ is effective in the accuracy of this model, anti-inference method and numerical simulation of the uniaxial tensile test is used for identification of GTN parameters. Proper parameters of GTN model is imported to the finite element analysis of Nakazima test for FLD prediction. Whereas FLD is dependent on forming history and strain path, forming limit stress diagram (FLSD) based on the GTN damage model is also used for forming limit prediction in the numerical method. Numerical results for FLD, FLSD and punch’s load-displacement are compared with experimental results. Results show that there is a good agreement between the numerical and experimental results. The main drawback of numerical results for prediction of the right-hand side of FLD which was concluded in other researchers’ studies was solved in the present study by using GTN damage model.

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