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.

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.

Direct Measurement of the Poisson’s Ratio of Human Patella Cartilage in Tension

2002 ◽  
Vol 124 (2) ◽  
pp. 223-228 ◽  
Author(s):  
Dawn M. Elliott ◽  
Daria A. Narmoneva ◽  
Lori A. Setton
Keyword(s):  
Articular Cartilage ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Surface Zone ◽  
Middle Zone ◽  
Linear Region ◽  
Tension Tests ◽  
Simple Tension ◽  
Viscoelastic Effects ◽  
Direct Measures

Articular cartilage has been shown to exhibit large transverse contractions when loaded in tension, suggesting the existence of large values for the Poisson’s ratio. Previous studies have suggested that this effect is dependent on amplitude of applied strain, so that a single Poisson’s ratio may not be sufficient to describe cartilage behavior. In this study, the Poisson’s ratio (ν), toe region modulus Eo, and linear region modulus E of human patellar articular cartilage were calculated in simple tension tests from optical analysis of the two-dimensional strain fields at equilibrium. The Poisson’s ratio was found to be independent of strain due to the absence of viscoelastic effects during testing. The Poisson’s ratio was found to be significantly higher in the surface zone (1.87±1.11, p<0.01) than in the middle zone (0.62±0.23), with no significant correlation of ν with age of the cartilage. In general, values for Poisson’s ratio were greater than 0.5, suggesting cartilage behavior in tension deviates from isotropy. Reported values for the Poisson’s ratio of cartilage in compression have been much lower than values measured here in tension, reflecting a mechanical contribution of the collagen fibers to anisotropy in tension but not compression. The toe-region modulus Eo was significantly higher in the surface zone (4.51±2.78 MPa, n=8) compared to the middle zone (2.51±1.93 MPa, n=10). In addition, the linear-region modulus E in the surface zone, but not middle zone (3.42±2.17 MPa, n=10), was found to correlate with age R=0.97,p<0.02 with values of surface zone E equal to 23.92±12.29 MPa n=5 for subjects under 70 yr of age, and 4.27±2.89 MPa n=3 for subjects over 70 yr. Moduli values and trends with depth were consistent with previous studies of human and animal cartilage. From direct measures of two independent material properties, ν and E, we calculated a shear modulus, G, which had not been previously reported for cartilage from tensile testing. Calculated values for surface zone G were 3.64±1.80 MPa for subjects under 70 yr old and 0.96±0.69 MPa for subjects over 70 yr old, and were significantly higher in the surface zone than in the middle zone (1.10±0.78 MPa). This study provides an intrinsic measure for the Poisson’s ratio of articular cartilage and its dependence on depth which will be important in understanding the nonlinear tension-compression and anisotropic behaviors of articular cartilage.

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 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.

Using the elastic modulus defect for diagnostics of plastic deformation of metal

2020 ◽  
pp. 34-35
Author(s):  
M.M. Matlin ◽  
V.A. Kazankin ◽  
E.N. Kazankina ◽  
A.I. Mozgunova ◽  
A.I. Sotnikova
Keyword(s):  
Plastic Deformation ◽  
Elastic Modulus ◽  
Elastic Properties ◽  
Modulus Of Elasticity ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Modulus Defect ◽  
Non Destructive

A non-destructive method for assessing the plastic deformation of a metal after processing a product is proposed, based on a change in the elastic properties of the material. Keywords metal, elastic properties, modulus of elasticity, Poisson's ratio, plastic deformation, non-destructive method, tension. [email protected]

A study of the anisotropic static and dynamic elastic properties of transversely isotropic rocks

Geophysics ◽  
2019 ◽  
Vol 84 (6) ◽  
pp. C281-C293 ◽  
Author(s):  
Fei Gong ◽  
Bangrang Di ◽  
Jianxin Wei ◽  
Pinbo Ding ◽  
He Tian ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Clay Minerals ◽  
Elastic Properties ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Dynamic Properties ◽  
Axial Stress ◽  
Poisson's Ratio ◽  
Static Young’S Modulus ◽  
Loading And Unloading

The elastic properties of rock are major factors affecting hydraulic fracturing. Static elastic properties can be estimated using geomechanical laboratory tests, whereas dynamic properties can be estimated from elastic-wave velocity and rock density. We prepared two synthetic shales containing different clay minerals and one natural shale and focused on the elastic properties for the full tensor of elasticity and their anisotropy. The static and dynamic properties of these dry samples were obtained based on triaxial tests during loading and unloading. The results suggest that the synthetic and natural shale indicate high similarity in the static and dynamic properties. The dynamic Young’s modulus and Poisson’s ratio increase with increasing axial stress during loading and unloading. For the static properties, the static Poisson’s ratio increases with axial stress during loading and unloading. However, differences exist between the static and dynamic Young’s moduli during loading, with the static Young’s modulus decreases with the increasing axial stress at a high stress level. In addition, the static Young’s modulus is consistently lower than the dynamic Young’s modulus during loading and unloading, but the static Poisson’s ratio is larger or smaller than the dynamic Poisson’s ratio. During loading and unloading, there could be approximately a 30% difference when estimating static elastic properties from the static-dynamic relations, depending on which static moduli are used. Furthermore, the static and dynamic properties of the samples are strongly anisotropic, and the anisotropy of elastic properties is sensitive to the axial stress and the clay minerals.

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