scholarly journals Inelastic constitutive equation on the basis of the distribution function of yield stress. 1st Report. Formulation of plastic constitutive equation.

1987 ◽  
Vol 53 (490) ◽  
pp. 1132-1136 ◽  
Author(s):  
Yasushi NIITSU ◽  
Kozo IKEGAMI
Keyword(s):  
Distribution Function ◽  
Constitutive Equation ◽  
Yield Stress

Identification of the constitutive equation by the indentation technique using plural indenters with different apex angles

2001 ◽  
Vol 16 (8) ◽  
pp. 2283-2292 ◽  
Author(s):  
Masatoshi Futakawa ◽  
Takashi Wakui ◽  
Yuji Tanabe ◽  
Ikuo Ioka
Keyword(s):  
Constitutive Equation ◽  
Yield Stress ◽  
Work Hardening ◽  
Indentation Technique ◽  
Work Hardening Coefficient ◽  
The Relationship ◽  
Stress Work ◽  
Hardening Coefficient ◽  
Depth Curve ◽  
Work Hardening Exponent

This paper describes a novel technique for determining the constitutive equation of elastic–plastic materials by the indentation technique using plural indenters with different apex angles. Finite element method (FEM) analyses were carried out to evaluate the effects of yield stress, work hardening coefficient, work hardening exponent, and the apex angle of indenter on the load–depth curve obtained from the indentation test. As a result, the characterized curves describing the relationship among the yield stress, work hardening coefficient, and the work hardening exponent were established. Identification of the constants of a constitutive equation was made on the basis of the relationship between the characterized curves and the hardness given by the load–depth curve. This technique was validated through experiments on Inconel 600 and aluminum alloy. The determined constitutive equation was applied to the FEM analyses to simulate the deformation including necking behavior under uniaxial tension. The analytical results are in good agreement with experimental results.

Determining the Anisotropy Coefficients of an Ultra Fine Grained Al6082 Alloy Subjected to ECAP

2007 ◽  
Vol 537-538 ◽  
pp. 215-222
Author(s):  
György Krállics ◽  
Arpad Fodor
Keyword(s):  
Constitutive Equation ◽  
Yield Stress ◽  
Continuum Mechanics ◽  
Equivalent Stress ◽  
Strain Curve ◽  
Equivalent Strain ◽  
Rigid Plastic ◽  
Fine Grained ◽  
Anisotropy Coefficients

Bulk Al6082 alloy is subjected to ECAP using route Bc. This paper focuses on the determination of the anisotropy coefficients and equivalent stress-equivalent strain curve using continuum mechanics equations. Assuming the material to be rigid-plastic, the parameters of the constitutive equation are determined with the aid of measuring the deformation and the uniaxial yield stress during upsetting tests in three perpendicular directions.

United void index for normalizing virgin compression of reconstituted clays

2020 ◽  
Vol 57 (10) ◽  
pp. 1497-1507
Author(s):  
Ling-Ling Zeng ◽  
Zhen-Shun Hong ◽  
Yu-Jun Cui
Keyword(s):  
Constitutive Equation ◽  
Yield Stress ◽  
Research Team ◽  
Physical Parameters ◽  
Scatter Problem ◽  
Independent Data ◽  
Stress Range ◽  
Empirical Correlations ◽  
Intrinsic Parameters ◽  
Compression Line

The intrinsic compression framework that uses the void index for normalizing the virgin compression of reconstituted clays has been widely applied for academic and practical purposes. Past studies have shown that the data of void index are scattered when the stress is out of the range from 100 to 1000 kPa. In this study, the key cause responsible for the scatter problem in the existing intrinsic compression framework is identified. A united void index is introduced for normalizing the compression curves of reconstituted clays over a wide stress range starting from the remoulded yield stress to 1000 kPa. The normalized unique line is termed the unified normalized compression line (UNCL). Its constitutive equation is established in terms of the united void index versus the effective vertical stress. The uniqueness of the UNCL is validated based on independent data from the literature and the data from the research team. It is suggested that the UNCL should be directly measured from the virgin compression. In the case without conducting consolidation tests, the correlations between the intrinsic parameters in the UNCL’s equation and two physical parameters are proposed for indirectly determining the UNCL. The accuracy of the empirical correlations is investigated via the comparisons between the calculated intrinsic parameters and the measurements.

A constitutive equation for thixotropic suspensions with yield stress by coarse-graining a population balance model

AIChE Journal ◽  
2016 ◽  
Vol 63 (2) ◽  
pp. 517-531 ◽  
Author(s):  
Paul M. Mwasame ◽  
Antony N. Beris ◽  
R. Betrum Diemer ◽  
Norman J. Wagner
Keyword(s):  
Constitutive Equation ◽  
Yield Stress ◽  
Coarse Graining ◽  
Population Balance ◽  
Balance Model ◽  
Population Balance Model

Transient Motion of Liquid Plugs With Yield Stress in Human Airways

2011 ◽  
Author(s):  
Parsa Zamankhan ◽  
Brian Helenbrook ◽  
Shuichi Takayama ◽  
James B. Grotberg
Keyword(s):  
Constitutive Equation ◽  
Yield Stress ◽  
Lung Diseases ◽  
Spectral Element ◽  
Bingham Fluid ◽  
Element Formulation ◽  
Arbitrary Lagrangian Eulerian ◽  
Governing Equations ◽  
Human Airways ◽  
Distribution Of Stresses

The airway closure due to capillary instability [1] occurs in lung diseases such as asthma, cystic fibrosis, or emphysema. The reopening process involves displacement of plugs constituted from mucus, a non-Newtonian fluid with a yield stress, in the airways. In this work the transient propagation of mucus plugs in a 2D channel is studied numerically, assuming that the mucus is a Bingham fluid. The governing equations are discretized by a spectral element formulation and the free surface is resolved with an Arbitrary Lagrangian Eulerian (ALE) approach [2]. The constitutive equation for a Bingham fluid is implemented through a regularized constitutive equation. According to the numerical results, the yield stress behavior of the plug modifies the plug shape, the pattern of the streamlines and the distribution of stresses in the plug domain and along the walls in a significant way. The distribution along the walls is a major factor in studying cell injuries.

Propagation of Liquid Plugs With Yield Stress in Human Airways

2010 ◽  
Author(s):  
Parsa Zamankhan ◽  
Shuichi Takayama ◽  
James B. Grotberg
Keyword(s):  
Constitutive Equation ◽  
Yield Stress ◽  
Lung Diseases ◽  
Bingham Fluid ◽  
Element Formulation ◽  
Governing Equations ◽  
Discontinuous Finite Element ◽  
Human Airways ◽  
Steady Propagation ◽  
Distribution Of Stresses

The airway closure due to the capillary instability [1] occurs in lung diseases such as asthma, cystic fibrosis, or emphysema. The reopening process involves with displacement of plugs constituted from mucus, a non-Newtonian fluid with a yield stress, in the airways. In this work the steady propagation of mucus plugs in a 2D channel is studied numerically, assuming that the mucus is a Bingham fluid. The governing equations are solved by a mixed-discontinuous finite element formulation and the free surface is resolved with the method of spines. The constitutive equation for Bingham fluid is implemented through a regularized constitutive equation. According to the numerical results, the yield stress behavior of the plug modifies the plug shape, the pattern of the streamlines and the distribution of stresses in the plug domain and along the walls in a significant way. The distribution along the walls is a major factor in studying cell injuries.

Boundary Migration Induced Plasticity during Recrystallization and Growth under Applied Stress

2007 ◽  
Vol 558-559 ◽  
pp. 533-537 ◽  
Author(s):  
Se Jong Kim ◽  
Yi Gil Cho ◽  
Dong Woo Suh ◽  
Sung Joon Kim ◽  
Gyo Sung Kim ◽  
...  
Keyword(s):  
Experimental Data ◽  
Constitutive Equation ◽  
Plastic Strain ◽  
Yield Stress ◽  
Applied Stress ◽  
Boundary Migration ◽  
Permanent Strain ◽  
Compressive Stresses

In general, plastic strain occurs over a certain stress, called yield stress. However, it has been reported that the permanent strain could happen during boundary migrating even under the extremely slight externally applied stress. In this study, we performed dilatometry experiments under the various compressive stresses and measured the amount of recrystallization and growth induced permanent strain. A new empirical constitutive equation was suggested to describe the recrystallization and growth induced plasticity. This equation was verified by comparing the calculated values with dilatometric experimental data under the various compressive stresses.

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