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.

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.

Viscosity Models for Drilling Fluids: Viscosity Parameters and Their Use

2019 ◽  
Author(s):  
Arild Saasen ◽  
Jan David Ytrehus
Keyword(s):  
Shear Rate ◽  
Yield Stress ◽  
Yield Point ◽  
Power Law ◽  
Physical Parameters ◽  
Fluid Viscosity ◽  
Reasonable Accuracy ◽  
Bingham Model ◽  
Viscosity Models ◽  
Power Law Exponent

Abstract The most common viscosity models used in the drilling industry are the Bingham, the Power-Law and the Herschel-Bulkley models. The scope of the present paper is to outline how to select the individual models, and how the models need to be re-formulated to be able to have parameters with a physical meaning. In principle, the Bingham model itself have physical parameters being the yield point and the plastic viscosity. However, the Bingham model very often only very poorly describe the viscosity in complex fluids. This yield stress can be described within a reasonable accuracy by application of the low-shear yield point. A similar problem exists with the Power-Law model resulting from the model’s absence of a yield stress. The compromise model is the Herschel-Bulkley model which contains a yield stress and a power-law term. This model describes the drilling fluid viscosity with reasonable accuracy and includes both the Bingham and Power-Law models as limit formulations. It is not possible to select fluids based on the Herschel-Bulkley traditional parameters alone. The reason is that the Herschel-Bulkley power-law term’s viscosity parameter has a unit dependent on its power-law exponent. In the present approach the fluid is described using a yield stress, a surplus stress at a characteristic shear rate of the fluid flow and finally a power-law exponent making the fluid applicable in the practical shear rate ranges. The surplus stress is no-longer dependent on other parameters. Hence, we have re-arranged the viscosity model to have independent measurable quantities.

A 3D Masonry-Like Model with Bounded Shear Stress

2017 ◽  
Vol 747 ◽  
pp. 20-27 ◽  
Author(s):  
Massimiliano Lucchesi ◽  
Barbara Pintucchi ◽  
Nicola Zani
Keyword(s):  
Shear Stress ◽  
Constitutive Equation ◽  
Convex Subset ◽  
Numerical Results ◽  
Stress Range ◽  
Symmetric Tensors ◽  
Elastic Materials ◽  
Linear Elastic ◽  
Non Linear

This paper deals with non linear elastic materials for which not all the stresses are admis-sible but only those which belong to the stress range, i.e. a closed and convex subset of the spaceof all symmetric tensors. The constitutive equation that has been formulated and explicitly solved issufficiently general to include, besides the so-called masonry-like materials, many others whose stressrange is obtained experimentally or is theoretically defined. The model, implemented into the finiteelement code MADY, has been used to analyze a masonry panel under a bi-directional monotonicallyincremental load and the obtained numerical results have been discussed.

scholarly journals A constitutive law for snow taking into account the compressibility

2004 ◽  
Vol 38 ◽  
pp. 145-149 ◽  
Author(s):  
Aloke Mishra ◽  
Puneet Mahajan
Keyword(s):  
Constitutive Equation ◽  
Iterative Scheme ◽  
Constant Strain Rate ◽  
Primary Creep ◽  
Constitutive Law ◽  
Density Range ◽  
Stress Range ◽  
Total Deformation ◽  
Hereditary Integral ◽  
Linear Spring

AbstractA constitutive law for snow derived from a complementary power potential is proposed. The total deformation of snow is divided into elastic and creep parts. A hereditary integral using Norton’s power law is employed to describe primary creep. The concept of effective stress, which takes compressibility of snow into account, is used to calculate creep deformation. The hereditary integral is approximated by a non-linear spring–dashpot model. Results from uniaxial compression experiments (stress range 15– 45 kPa) on sieved snow of density range 180–470 kgm-3 were used to determine the constants appearing in the constitutive equation. The response of snow to constant strain rate (7.4×10-6 s-1 to 2.2×10-5 s-1) under bilaterally confined conditions was found with an iterative scheme employing the proposed constitutive law. The simulated results agree well with the measured axial stresses and volumetric changes.

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
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