Plastic Response of Polycrystalline Metals Subjected to Complex Deformation History

1984 ◽  
Vol 106 (4) ◽  
pp. 299-303 ◽  
Author(s):  
Jan Kratochvil ◽  
Masataka Tokuda
Keyword(s):  
Constitutive Equations ◽  
Bauschinger Effect ◽  
Plastic Response ◽  
Deformation History ◽  
Microscopic Mechanism ◽  
Complex Deformation ◽  
Polycrystalline Metals ◽  
Polycrystal Plasticity ◽  
Basic Features ◽  
Good Agreement

We attempt to formulate the elasto-plastic constitutive equations which reflect the basic features of the microscopic mechanism of plastic deformation and at the same time remains sufficiently simple to be applicable in FEM solution of the practical problems. The constitutive equations are based on a simplified verison of polycrystal plasticity. In modeling of the properties of single crystal grains of the polycrystal attention is paid to active and latent hardenings, and especially to the Bauschinger effect. The stress response along three sets of typical examples of complex deformation histories are predicted and compared with precise data of tension-torsion tests. The predictions are in good agreement with the observed behavior.

scholarly journals The Rosebel gold district (Trans-Amazonian belt, Suriname), a new structural framework

2021 ◽  
Author(s):  
Denis Gapais ◽  
Gilian Alimoenadi ◽  
Nicole Balraadjsing ◽  
Benoît Poupeau
Keyword(s):  
Fault Slip ◽  
Finite Strains ◽  
Continental Lithosphere ◽  
Deformation History ◽  
Complex Deformation ◽  
Crustal Shortening ◽  
Strain Pattern ◽  
Structural Framework

The Rosebel gold district belongs to the Paleoproterozoic Trans-Amazonian belt associated with sub-meridian crustal shortening. Here, we present new structural observations (cleavage, stretching lineations, veins, fault slip data, aeromagnetic maps). Regional cleavages are steeply dipping and bear steeply plunging stretching lineations. Finite strains are of flattening type. Fault slip data reveal a complex deformation history. The overall strain pattern of the reflects vertical motions, a feature consistent with pop-down tectonics involving vertical stretch and burial of supracrustal deposits during horizontal shortening of a hot and weak continental lithosphere.

Effects of Detwinning on the Inelasticity of AZ31B Sheets During Cyclic Loading and Unloading

2018 ◽  
Vol 10 (09) ◽  
pp. 1850095 ◽  
Author(s):  
H. Wang ◽  
D. Tang ◽  
D. Y. Li ◽  
Y. H. Peng ◽  
P. D. Wu
Keyword(s):  
Cyclic Loading ◽  
Magnesium Alloys ◽  
Plasticity Model ◽  
Inelastic Behavior ◽  
Deformation History ◽  
Cyclic Loading And Unloading ◽  
Polycrystal Plasticity ◽  
Self Consistent ◽  
Loading And Unloading ◽  
Previous Loading

Magnesium alloys exhibit significant inelastic behavior during unloading, especially when twinning and detwinning are involved. It is commonly accepted that noteworthy inelastic behavior will be observed during unloading if twinning occurs during previous loading. However, this phenomenon is not always observed for Mg sheets with strong rolled texture. Therefore, the inelasticity of AZ31B rolled sheets with different rolled textures during cyclic loading-unloading are investigated by elastic viscoplastic self-consistent polycrystal plasticity model. The incorporation of the twinning and detwinning model enables the treatment of detwinning, which plays an important role for inelastic behavior during unloading. The effects of texture, deformation history, and especially twinning and detwinning on the inelastic behaviors are carefully investigated and found to be remarkable. The simulated results are in agreement with the available experimental observations, which reveals that the inelastic behavior for strongly rolled sheets is very different than the extruded bars.

Simplified Elasto-Plastic Response Analysis of Piping: Considering In-Plane, Out-of-Plane and the Mixed Bending of Elbow

2006 ◽  
Author(s):  
Akihito Otani ◽  
Syozaburo Toyoda ◽  
Izumi Nakamura ◽  
Hajime Takada
Keyword(s):  
Plastic Deformation ◽  
Seismic Excitation ◽  
Response Analysis ◽  
Plastic Response ◽  
Additional Method ◽  
Damping Effect ◽  
Piping Systems ◽  
Out Of Plane ◽  
Plane Bending ◽  
Good Agreement

When piping systems are subjected to extreme seismic excitation, they undergo a plastic deformation that produces a large damping effect via energy dissipation. Based on our studies of the damping effect of the elasto-plastic response of piping, we have presented a simplified method for predicting the elasto-plastic response of piping in PVP conferences over the last several years. The method has taken the plastic deformation of in-plane bending elbows into consideration. The elasto-plastic response predicted by the method resulted in good agreement with piping model excitation tests. In this paper, we report an additional method to consider out-of-plane bending elbow and the mixed bending of in-plane and out-of-plane bending. The simulation results by this method and the comparisons with 3D piping model excitation tests are also reported.

A Generalized von Mises Criterion for Yield and Fracture

1980 ◽  
Vol 47 (2) ◽  
pp. 297-300 ◽  
Author(s):  
W. H. Yang
Keyword(s):  
Bauschinger Effect ◽  
Hydrostatic Stress ◽  
Fracture Criteria ◽  
Deformation History ◽  
Von Mises Criterion ◽  
Effect On Yield ◽  
Von Mises ◽  
New Criterion ◽  
Physical Phenomena ◽  
Special Case

Yield and fracture criteria for real materials are to a varying degree affected by a state of hydrostatic stress. Some materials, after certain deformation history, exhibit different yield point when the direction of the stress is reversed, a behavior known as the Bauschinger effect. These physical phenomena are not represented by the von Mises criterion. Based on a convexity theorem of matrices, a generalization of the von Mises criterion is presented. The new criterion satisfies the convexity requirement of plasticity theory and, with two scalar functions of deformation history α and β, produces a class of hardening behavior. The current values of α and β account for the effect of hydrostatic stress and an aspect of the Bauschinger effect on yield and fracture. The generalized criterion reduces to the form of the von Mises criterion as a special case.

Prediction of spring-back in anisotropic sheet metals

2004 ◽  
Vol 218 (6) ◽  
pp. 651-661 ◽  
Author(s):  
V T Nguyen ◽  
Z Chen ◽  
P F Thomson
Keyword(s):  
Constitutive Equations ◽  
Bauschinger Effect ◽  
Yield Criterion ◽  
Yield Function ◽  
Alloy Sheet ◽  
Sheet Metals ◽  
Spring Back ◽  
Bending Tests ◽  
Numerical Predictions ◽  
Draw Bending

Constitutive equations for plane stress problems based on the modified form of a non-quadratic yield criterion suitable for aluminium alloy sheet were derived by Barlat et al. to account for the Bauschinger effect (BE). Numerical predictions of spring-back based on the original yield function and its modified form wer performed and compared with the results of draw-bending tests. The results show the necessity of including the BE in the constitutive equations to enhance the accuracy in predicting spring-back.

THE MEAN WORK FUNCTION EFFECTIVE FOR POSITIVE ION EMISSION FROM POLY- AND MONOCRYSTALLINE SURFACES

2005 ◽  
Vol 12 (01) ◽  
pp. 107-113 ◽  
Author(s):  
HIROYUKI KAWANO
Keyword(s):  
Work Function ◽  
Electron Emission ◽  
Heterogeneous Surfaces ◽  
Polycrystalline Metals ◽  
Typical Data ◽  
The Mean ◽  
Ion Emission ◽  
Thermionic Property ◽  
Positive Ion ◽  
Good Agreement

To clarify the thermionic property of solids, the mean work function effective for positive ion from polycrystalline surfaces (ϕ+) is theoretically studied together with that for electron emission (ϕe). The theoretical values of ϕ+ and ϕe thus evaluated typically with W are in good agreement respectively with those experimental ones accepted today. The thermionic contrast (Δϕ* ≡ ϕ+ – ϕe) is determined to be 0.56–0.57eV for W. For other polycrystalline metals (Nb, Mo, Ta, Re, Ir and Pt), it ranges from about 0.4 to 0.8eV in contrast with monocrystalline ones having Δϕ* = 0. Consequently, the fact of Δϕ* > 0 should be taken into consideration with any polycrystalline surface, and ϕ+ should be adopted whenever we try to analyze those data on positive ion emission due to any of the processes such as thermal stimulation and ion bombardment at heterogeneous surfaces. This article concludes that such typical data on thermal- and secondary-positive ion emissions are analyzed reasonably by adoption of ϕ+ instead of ϕe.

scholarly journals Numerical modeling transient flow in plastic pipes

2019 ◽  
Vol 286 ◽  
pp. 07001
Author(s):  
N. Achak ◽  
B. Bahrar ◽  
K. Gueraoui
Keyword(s):  
Numerical Modeling ◽  
Constitutive Equations ◽  
Method Of Characteristics ◽  
Transient Flow ◽  
Pipe Wall ◽  
Digital Processing ◽  
Numerical Code ◽  
Plastic Pipes ◽  
And Behavior ◽  
Good Agreement

We present a numerical code for calculating transient flow in plastic pipes, especially in the polyethylene pipe, to analysis effect of material viscoelasticity on water hammer phenomena. The set partial differential equations to be solved is obtained using conservation laws and behavior for the fluid and the pipe wall, associated with constitutive equations of the two media, and relationships compatibility of interfaces on velocities and stresses. A global digital processing is achieved using the method of characteristics. The results obtained are in good agreement with those found in the literature.

A Coarse Model for the Multiaxial Elastic-Plastic Response of Ductile Porous Materials

2019 ◽  
Vol 86 (8) ◽  
Author(s):  
Andreas Schiffer ◽  
Panagiotis Zacharopoulos ◽  
Dennis Foo ◽  
Vito L. Tagarielli
Keyword(s):  
Mechanical Response ◽  
Hydrostatic Stress ◽  
Parent Material ◽  
Porous Solids ◽  
Plastic Response ◽  
Elastic Plastic ◽  
Numerical Studies ◽  
Coarse Model ◽  
Modeling Strategy ◽  
Good Agreement

We propose a modeling strategy to predict the mechanical response of porous solids to imposed multiaxial strain histories. A coarse representation of the microstructure of a porous material is obtained by subdividing a volume element into cubic cells by a regular tessellation; some of these cells are modeled as a plastically incompressible elastic-plastic solid, representing the parent material, while the remaining cells, representing the pores, are treated as a weak and soft compressible solid displaying densification behavior at large compressive strains. The evolution of homogenized deviatoric and hydrostatic stress is explored for different porosities by finite element simulations. The predictions are found in good agreement with previously published numerical studies in which the microstructural geometry was explicitly modeled.

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