scholarly journals Влияние микротрещин на коэффициент Пуассона при пластическом деформировании аустенитной стали

2022 ◽  
Vol 92 (3) ◽  
pp. 405
Author(s):  
С.В. Кириков ◽  
В.В. Мишакин ◽  
В.А. Клюшников
Keyword(s):  
Experimental Data ◽  
Plastic Deformation ◽  
Poisson’S Ratio ◽  
Damage Accumulation ◽  
Theoretical Calculations ◽  
Acoustic Method ◽  
12Kh18n10t Steel ◽  
Martensite Phase ◽  
Poisson's Ratio ◽  
Theoretical Dependence

We researched the influence of damage accumulation on the Poisson's ratio measured by echo-pulse acoustic method during plastic deformation of 12Kh18N10T steel. On the basis of the obtained experimental data we calculated the partial contributions to the change in the Poisson's ratio of damage accumulation and separation of the strain induced martensite phase. The characteristics of stable cracks forming near strain martensite particles at small degrees of plastic strain have been analyzed by computer simulation. The theoretical dependence of the change in the Poisson's ratio due to crack formation during plastic deformation has been constructed. A good agreement between the experimental data and theoretical calculations has been obtained.

The Influence of the Bauschinger Effect on the Yield Stress, Young’s Modulus, and Poisson’s Ratio of a Gun Barrel Steel

2005 ◽  
Vol 128 (2) ◽  
pp. 179-184 ◽  
Author(s):  
J. Perry ◽  
M. Perl ◽  
R. Shneck ◽  
S. Haroush
Keyword(s):  
Plastic Deformation ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Bauschinger Effect ◽  
Young's Modulus ◽  
Poisson's Ratio ◽  
Compression Tests ◽  
Residual Stress Field ◽  
Gun Barrel

The Bauschinger effect (BE) was originally defined as the phenomenon whereby plastic deformation causes a loss of yield strength restraining in the opposite direction. The Bauschinger effect factor (BEF), defined as the ratio of the yield stress on reverse loading to the initial yield stress, is a measure of the magnitude of the BE. The aim of the present work is to quantitatively evaluate the influence of plastic deformation on other material properties such as Young’s modulus and Poisson’s ratio for gun barrel steel, thus extending the definition of the Bauschinger effect. In order to investigate the change in this material’s properties resulting from plastic deformation, several uniaxial tension and compression tests were performed. The yield stress and Young’s modulus were found to be strongly affected by plastic strain, while Poisson’s ratio was not affected at all. An additional result of these tests is an exact zero offset yield point definition enabling a simple evaluation of the BEF. A simple, triphase test sufficient to characterize the entire elastoplastic behavior is suggested. The obtained experimental information is readily useful for autofrettage residual stress field calculations.

A Multiaxial Stochastic Constitutive Law for Concrete With Dilatancy: Part II—Comparison With Experimental Data

1992 ◽  
Vol 59 (2) ◽  
pp. 289-294 ◽  
Author(s):  
Y. H. Won ◽  
A. Fafitis
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Peak Stress ◽  
Concrete Specimen ◽  
Uniaxial Stress ◽  
Constitutive Law ◽  
Poisson's Ratio ◽  
Uniaxial Tensile ◽  
Empirical Formulas

The salient features and concepts of a model developed in Part I of this paper are reviewed. The model is extended to include dilatancy and shear compaction which are determined from uniaxial stress-strain relationships. The parameters of the model are the peak stress, initial elastic modulus, and tangential Poisson’s ratio. The peak stress is assumed equal to the compressive strength of the concrete specimen, the initial elastic modulus and the Poisson’s ratio is calculated by proposed empirical formulas. Predictions of the model compare favorably with experimental data reported by various investigators. Responses of concrete specimens subjected to prescribed triaxial proportional stresses, triaxial proportional strains and stresses, hydrostatic plus stress combinations with loading paths on the deviatoric stress plane, biaxial compressive, biaxial tensile, and uniaxial tensile loadings are predicted and compared with test data. All predictions are satisfactory.

Analysis of Spherical Contact Models for Differential Hardness as a Function of Poisson's Ratio

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Giuseppe Pintaude
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Yield Stress ◽  
Poisson’S Ratio ◽  
Large Deformations ◽  
Poisson's Ratio ◽  
Spherical Contact ◽  
Indentation Process ◽  
Contact Models ◽  
The Difference

A differential hardness is needed for a spherical indenter to avoid large deformations of it during an indentation process. Tabor proposes a criterion for this, where the ball hardness should be at least 2.5 times harder than the specimen. Later, five models expand the Tabor proposal, such that the critical interference corresponding to the inception of plastic deformation depends on the Poisson's ratio. This paper discusses the difference among these models, showing that they can be divided in two groups only. In addition, their similarity depending on the specific mechanical properties of tested material was used to make the conversion between yield stress and hardness.

Hydraulic Fracturing Mechanical Mechanism Analyses for Soft Seams Considering Strain Softening Character

2013 ◽  
Vol 868 ◽  
pp. 319-325 ◽  
Author(s):  
Yi Lei ◽  
Wen Bin Wu
Keyword(s):  
Plastic Deformation ◽  
Elastic Modulus ◽  
Internal Friction ◽  
Hydraulic Fracturing ◽  
Poisson’S Ratio ◽  
Strain Softening ◽  
Fracture Initiation ◽  
Poisson's Ratio ◽  
Angle Of Internal Friction ◽  
Initiation Pressure

Mathematical model based on elasticity is not suitable for soft seam hydraulic fracturing mechanism study because its intensity is small, Poisson's ratio is relatively large, and its prone to plastic deformation. Based on plastic mechanics, the theory of large deformation and fracture mechanics theory, hydraulic fracturing of soft coal seam is divided into three phases, namely, coal bed compaction, fracture initiation and crack propagation from the view of the deformation mechanism, the occurring and developing mechanism. The initiation pressure of soft seams considered strain softening character after plastic deformation is obtained on the basis of above. The result shows that the initiation pressure is related to elastic modulus, Poisson's ratio, the angle of internal friction and residual strength. Elastic modulus is inversely proportional to the initiation pressure, the greater its value, the smaller the initiation pressure; but Poisson's ratio, the angle of internal friction and the residual strength and fracture initiation pressure is directly proportional relationship, the greater its value, since the smaller the crack pressure.

scholarly journals Extracting real-crack properties from nonlinear elastic behavior of rocks: abundance of cracks with dominating normal compliance and rocks with negative Poisson's ratio

2017 ◽  
Author(s):  
Vladimir Y. Zaitsev ◽  
Andrey V. Radostin ◽  
Elena Pasternak ◽  
Arcady Dyskin
Keyword(s):  
Experimental Data ◽  
Poisson’S Ratio ◽  
A Priori ◽  
Poisson's Ratio ◽  
Elastic Behavior ◽  
Crack Model ◽  
Negative Poisson’S Ratio ◽  
Normal Compliance ◽  
S Wave ◽  
Negative Poisson's Ratio

Abstract. Results of examination of experimental data on nonlinear elasticity of rocks using experimental pressure-dependences of P- and S-wave velocities from various literature sources are presented. Overall, over 90 rock samples are considered. Interpretation of the data is performed using an effective-medium description in which cracks are considered as compliant defects (cracks) with independent shear and normal compliances without specifying a particular crack model with an a priori given ratio of the compliances. Comparison with the experimental data indicated abundance of cracks (~ 80 %) with the normal-to-shear compliance ratios significantly exceeding the values typical of conventionally used crack models (such as penny-shape cuts or thin ellipsoidal cracks). Correspondingly, rocks with such cracks demonstrate strongly decreased Poisson's ratio including a significant portion of rocks (~ 45 %) exhibiting negative Poisson's ratios at lower pressures, for which the concentration of not yet closed cracks is maximal. The obtained results indicate the necessity of further development of crack models to account the revealed numerous examples of cracks with strong domination of normal compliance. Discovering such a significant number of naturally auxetic rocks is in contrast with the conventional viewpoint that occurrence of negative Poisson's ratio is an exotic fact that is mostly associated with specially engineered structures.

Accumulation and Healing of Damage during Plastic Metal Forming Simulation and Experiment

2012 ◽  
Vol 528 ◽  
pp. 61-69 ◽  
Author(s):  
S.V. Smirnov
Keyword(s):  
Experimental Data ◽  
Plastic Deformation ◽  
Metal Forming ◽  
Damage Accumulation ◽  
Adaptive Model ◽  
Steel Blank ◽  
Forming Simulation ◽  
Closed Die Forging ◽  
Plastic Metal ◽  
Simulation And Experiment

Based on the analysis of experimental data on measuring metal density under plastic deformation, an adaptive model of damage accumulation, which takes into account the transient processes of damage variation with changes in loading conditions, has been formulated. The analysis of damage in the process of cold closed-die forging of a lid-type steel blank being taken as an example, the applicability of the model to the prediction of fracture in the optimization of industrial metal forming technologies has been demonstrated.

Elastic and Inelastic Recovery After Plastic Deformation of DQSK Steel Sheet

2003 ◽  
Vol 125 (3) ◽  
pp. 237-246 ◽  
Author(s):  
Limin Luo ◽  
Amit K. Ghosh
Keyword(s):  
Plastic Deformation ◽  
Poisson’S Ratio ◽  
Steel Sheet ◽  
Rolling Direction ◽  
Poisson's Ratio ◽  
Inelastic Behavior ◽  
Microplastic Strain ◽  
Empirical Relations ◽  
Viscoelastic Effects ◽  
Loading And Unloading

Strain recovery after plastic prestrain and associated elastic and inelastic behavior during loading and unloading of DQSK steel sheet are measured. Average tangent modulus and Poisson’s ratio during unloading and reloading are found to differ from their elastic values in the undeformed state, and they also vary as a function of stress. This modulus, often referred to as the “springback modulus,” decreases with plastic prestrain rapidly for prestrain values <2 percent and decays slowly for larger values of prestrain, while the average Poisson’s ratio during unloading increases with plastic prestrain initially rapidly and then remains almost unchanged at larger prestrain. Changes in the springback modulus and Poisson’s ratio are shown to be due to recovery of microplastic strain and not due to viscoelastic effects. Springback modulus and Poisson’s ratio are anisotropic, showing a maximum in modulus and a minimum in Poisson’s ratio at 45 deg to rolling direction. To describe the combination of recoverable inelastic and elastic deformation as a function of plastic prestrain, a set of equations has been developed based upon a previously developed constitutive model. Calculated results are capable of explaining experimental results on modulus and Poisson’s ratio changes. Implication of the results on “springback” is illustrated and empirical relations are obtained.

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