Forming Limit Analysis of Hexagonal Metal Considering Volume Fraction of Deformation Twinning

2019 ◽  
Vol 794 ◽  
pp. 226-231
Author(s):  
Tomoaki Koga ◽  
Yuichi Tadano
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Crystal Plasticity ◽  
Limit Analysis ◽  
Volume Fraction ◽  
Deformation Twinning ◽  
Forming Limit ◽  
Strain Paths ◽  
Homogenization Scheme ◽  
Slip Deformation

In the plastic deformation of hexagonal metals, deformation twinning plays an important role as well as slip deformation. Therefore, a modelling of deformation twinning is essential in the crystal plasticity modeling. In this study, a model considering the volume fraction of deformation twinning is presented in the framework of crystal plasticity, and it is combined with a finite element-based homogenization scheme to represent the polycrystalline behavior. The presented model is adopted to a sheet necking formulation. Plastic flow behaviors under several strain paths are evaluated using the present framework, and the effect of volume fraction of deformation twinning on the formability of hexagonal metal is discussed.

Effect of microstructural constituents and morphological characteristics on low cycle fatigue behaviour of inter-critically annealed 20MnMoNi55 steel

2021 ◽  
pp. 146442072110387
Author(s):  
Parichay Basu ◽  
Sanjib K Acharyya ◽  
Prasanta Sahoo
Keyword(s):  
Finite Element ◽  
Strain Amplitude ◽  
Crystal Plasticity ◽  
Volume Fraction ◽  
Low Cycle Fatigue ◽  
Stress Triaxiality ◽  
Morphological Characteristics ◽  
Strain Curve ◽  
Cycle Fatigue ◽  
Microstructural Parameters

The effect of varying microstructural parameters on the cyclic behaviour of dual-phase steels was studied on the basis of experimental and micromechanical finite-element simulated results. The initial bainitic morphology of as-received 20MnMoNi55 steel was transformed into ferrite and martensite through proper inter-critical heat treatment procedures. Strain-controlled low cycle fatigue tests were conducted at room temperature with different strain amplitudes at a specific strain rate of 10−3/s. The cyclic stress–strain curve, obtained through joining the peak stresses of hysteresis loops corresponding to different strain amplitude, shows an increase in strain hardening with an increase in volume fraction of martensite. Whereas the rate of cyclic softening, considering the decrease in stress amplitude with respect to elapsed cycles, increases with increasing strain amplitude. Inclusive of all affecting microstructural parameters, an original microstructure-based representative volume element associated with a crystal plasticity-based material model was adopted for conducting micromechanical finite-element simulation. In addition to several parameters associated with a crystal plasticity model, consideration of initial geometrically necessary dislocation density in constituent phases resulted in the accurate prediction of a hysteresis loop at low strain amplitude as compared with the experimental results. A variation of stress triaxiality built up in ferrite matrix with martensite fraction along with deformation inhomogeneity between ferrite and martensite was also observed through a strain partitioning phenomenon obtained from finite-element simulated results.

Modeling of TWIP Steel Tensile Behavior with Crystal Plasticity Finite Element Method

2014 ◽  
Vol 926-930 ◽  
pp. 162-165
Author(s):  
Yuan Yuan Wang ◽  
Xin Sun ◽  
Yan Dong Wang ◽  
Xiao Hua Hu ◽  
Hussein M. Zbib
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Crystal Plasticity ◽  
Twip Steel ◽  
Volume Fraction ◽  
Local Stress ◽  
Mechanical Twinning ◽  
Tensile Behavior ◽  
Deformation Condition ◽  
Crystal Plasticity Finite Element

We developed a plane-strain crystal plasticity finite element (CPFE) numerical model to predict the tensile behavior of twinning-induced plasticity (TWIP) steel with both slip and mechanical twinning as the main deformation modes. Our CPFE model may not only predict well the tensile stress versus strain (S-S) curve but also capture the variation in the volume fraction of twins with a reasonable accuracy. The nucleation of mechanical twin is obviously controlled by the stress concentration. At the same time, the growth of twin may either lead to a stress relaxation in the matrix or cause a local stress concentration around twin, which depends on the deformation condition.

Mean Field and Finite Element Modeling of Static and Dynamic Recrystallization

2012 ◽  
Vol 715-716 ◽  
pp. 737-737
Author(s):  
Roland E. Logé ◽  
P. Bernard ◽  
K. Huang ◽  
S. Bag ◽  
M. Bernacki
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Finite Element ◽  
Dynamic Recrystallization ◽  
Level Set ◽  
Volume Fraction ◽  
Mean Field ◽  
Quantitative Prediction ◽  
Finite Element Approach ◽  
Element Approach

Quantitative prediction of grain size and recrystallized volume fraction is still a real challenge for many alloys, and even for simple materials when subjected to complex thermal/mechanical histories, as in multi-pass (industrial) processing. A first step is therefore taken in the direction of multiscale modelling of recrystallization, by considering digital polycrystalline microstructures. These synthetic mesoscopic microstructures are meshed adaptively and anisotropically, with refinement close to the grain boundaries. Crystal plasticity finite element (CPFEM) simulations are combined with a level set framework to model primary recristallization, following plastic deformation. In the level set method, the kinetic equation describing interface motion uses the calculated stored energy field provided by CPFEM calculations, and works on the same mesh. Discontinuous dynamic recrystallization can be modelled within the same approach, effectively coupling plastic deformation with nucleation and growth processes. Parallel to the finite element approach, a mean field model is developed in the general context of multi-pass processing. The model considers categories of grains based on two state variables : grain size and total dislocation density. As opposed to the finite element approach, there is no crystallographic or topological information. It is computationally much cheaper and therefore suitable for direct coupling at the scale of forming processes, for industrial applications. The parameters of the model can be identified from inverse analysis, using experimental stress-strain curves, recrystallized volume fractions, and grain sizes. Mean field and finite element models are compared, and it is shown that the detailed information provided by finite element simulations can be used to calibrate or optimize the mean field method.

scholarly journals Multiscale Finite Element Simulation of Forming Processes Based on Crystal Plasticity

2014 ◽  
Vol 611-612 ◽  
pp. 545-552
Author(s):  
Komi Soho ◽  
Farid Abed Meraim ◽  
Xavier Lemoine ◽  
Hamid Zahrouni
Keyword(s):  
Finite Element ◽  
Crystal Plasticity ◽  
Texture Evolution ◽  
Constitutive Models ◽  
Rolling Process ◽  
Finite Element Software ◽  
Software Packages ◽  
Element Simulation ◽  
Coupling Strategy ◽  
Strain Paths

For the numerical simulation of sheet metal forming processes, the commercial finite element software packages are among the most commonly used. However, these software packages have some limitations; in particular, they essentially contain phenomenological constitutive models and thus do not allow accounting for the physical mechanisms of plasticity that take place at finer scales as well as the associated microstructure evolution. In this context, we propose to couple the Abaqus finite element code with micromechanical simulations based on crystal plasticity and a self-consistent scale-transition scheme. This coupling strategy will be applied to the simulation of rolling processes, at different reduction rates, in order to estimate the evolution of the mechanical properties. By following some appropriately selected strain paths (i.e., strain lines) along the rolling process, one can also predict the texture evolution of the material as well as other parameters related to its microstructure. Our numerical results are compared with experimental data in the case of ferritic steels produced by ArcelorMittal.

Analysis of a Test Method of Sheet Metal Formability Using the Finite-Element Method

1986 ◽  
Vol 108 (1) ◽  
pp. 3-8 ◽  
Author(s):  
C. H. Toh ◽  
Y. C. Shiau ◽  
Shiro Kobayashi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Sheet Material ◽  
Surface Strain ◽  
Test Method ◽  
304 Stainless Steel ◽  
Forming Limit ◽  
Rigid Plastic ◽  
Strain Paths ◽  
Element Method

The rigid-plastic finite element method was used to study the formability of sheet materials. In the finite element simulations, sheet material was assumed to be rigid plastic and to follow Hill’s anisotropic yield criterion and its associated flow rules. The work hardening effect and Coulomb friction were incorporated into the analysis. Hasek’s test, hemispherical punch stretching of the circular blank with circular cutoff, was analyzed in detail by simulation. The computed solutions were obtained using different blank geometries and coefficients of friction between the tool-sheet interface. Strain paths of critical elements were plotted in major and minor surface strain space. Experiments were also carried out using AISI 304 stainless steel sheets, and the results were compared with predictions for load-displacement curves and thickness strain distributions. Further, an attempt was made to construct a forming limit curve based on the detailed analysis of the test by computation.

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