scholarly journals On the Experimental Determination of Poisson’s Ratio for Intact Rocks and Its Variation as Deformation Develops

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Lu Dong ◽  
Hongfa Xu ◽  
Pengxian Fan ◽  
Zhichou Wu
Keyword(s):  
Uniaxial Tension ◽  
Poisson’S Ratio ◽  
Axial Strain ◽  
Deformation Modulus ◽  
Poisson's Ratio ◽  
Lateral Strain ◽  
Compression Tests ◽  
Rock Engineering ◽  
Red Sandstone

Poisson’s ratio is of crucial importance for the theoretical and numerical analysis of rock engineering. It is an elastic parameter of the material and the ratio of the absolute value of lateral strain and axial strain when the material is under uniaxial tension or compression. However, it was rarely investigated compared with deformation modulus and strength. Rock materials are different from metal materials. The pure elastic deformation stage is usually very short or nonexistent in the process of uniaxial tension or compression. In this paper, in order to explore the behavior of Poisson’s ratio, uniaxial compression tests according to The International Society for Rock Mechanics and Rock Engineering are performed on standard specimens of granite, marble, red sandstone, carbonate rock, coral concrete, etc. According to the results, Poisson’s ratio, both the secant Poisson’s ratio and tangent Poisson’s ratio, increase with the externally applied stress. Therefore, regarding it as an elastic constant is worthy of a second thought. If the midpoint of the stress interval is fixed in the 50% of uniaxial compressive strength, the average Poisson’s ratio is almost impervious to the varying span of the stress interval. In addition, the average Poisson’s ratio is immune to the nonlinear deformation in the early loading stage. Thus, the average Poisson’s ratio is a better index than the secant Poisson’s ratio in describing the relationship between axial and lateral strains of hard rocks. The determination of Poisson’s ratio of soft rocks needs further investigation because Poisson’s ratio tends to exceed the theoretical limit in relatively low stress levels. The proposed viewpoint provides a deeper insight into the testing, determining, and using of Poisson’s ratio.

On the Indentation Testing of Articular Cartilage: Determination of the Effective Poisson’s Ratio Using Two Different-Sized Punches

2008 ◽  
Author(s):  
Eugene T. Kepich ◽  
Roger C. Haut
Keyword(s):  
Articular Cartilage ◽  
Poisson’S Ratio ◽  
Direct Determination ◽  
Collagen Fibers ◽  
Poisson's Ratio ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Collagen Network ◽  
Lateral Expansion

Effective Poisson’s ratio (EPR) of articular cartilage in compression is an important parameter, which is inversely correlated with stiffness of the collagen fibers [1]; and thus, if known, could provide valuable information about integrity of the collagen network in the tissue. Unfortunately, direct determination of the EPR by measuring lateral expansion during unconfined compression tests [2], while being effective, due to it’s destructive nature many times is not desired and/or hard to apply in practice. Optically-determined values of equilibrium EPR for bovine humeral articular cartilage using this method are reported to be in range 0.185±0.0065.

scholarly journals Determining the concrete stiffness matrix through ultrasonic testing

2011 ◽  
Vol 31 (3) ◽  
pp. 427-437 ◽  
Author(s):  
Raquel Gonçalves ◽  
Milton Giacon Júnior ◽  
Igor M. Lopes
Keyword(s):  
Ultrasonic Testing ◽  
Stiffness Matrix ◽  
Poisson’S Ratio ◽  
Cylindrical Specimen ◽  
Poisson's Ratio ◽  
Compression Tests ◽  
Modulus Of Deformation ◽  
Ultrasonic Propagation ◽  
Concrete Characterization

The determination of the modulus tangent (Eci ) and of the modulus secant (Ecs) of the concrete can be done using compression test but, to be simpler, it is used relations with characteristic strength (f ck). Relations are also used to determine the transversal modulus (Gc) and, in the case of the Poisson's ratio (ν), a fixed value 0.20 is established. The objective of this research was to evaluate the use of the ultrasonic propagation waves to determine these properties. For the tests were used specimens with f ck varying from 10 to 35 MPa. For the ultrasonic tests were used cylindrical and cubic specimens. The modulus of deformation obtained by ultrasound was statistically equivalent to the obtained by compression tests. The results of modules obtained using the relations with f ck was far away from those obtained by ultrasound or by compression tests. The Poisson's ratio obtained by ultrasound was superior to the fixed value. We can conclude that the concrete characterization by ultrasound is consistent and, to this characterization the cylindrical specimen, normally used to determine f ck, can be used.

The Elastic Modulus and Poisson's Ratio of Laminated Bamboo Guadua angustifolia

2015 ◽  
Vol 668 ◽  
pp. 126-133 ◽  
Author(s):  
Caori Patricia Takeuchi ◽  
Martin Estrada ◽  
Dorian Luis Linero
Keyword(s):  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Vascular Bundles ◽  
Compression Tests ◽  
Laminated Bamboo ◽  
Group 2 ◽  
Natural Composite

Laminated bamboo is a natural composite material with cellulose fibers, parenchyma cells, and vascular bundles. The mechanical characterization of this material includes not only the determination of its strength, but also of its elastic constants. Given the anisotropic nature of the laminated material, compression tests were performed on three groups of specimens. The elastic modulus in the load direction and the Poisson's ratio were determined, and the results showed that the material's physical anisotropy causes an anisotropic mechanical behavior. The average values obtained for the elastic modulus ranged from 30044 MPa for group 1 to 265 MPa for group 2. The results of the test to determine the Poisson's ratio in compression perpendicular to the fibers, ranged from 0.013 to 0.278 whereas those obtained in compression parallel to the fibers, ranged from 0.621 to 1.506.

An Iterative Axial and Lateral Ultrasound Strain Estimator Using Subband Division

2020 ◽  
Vol 10 (5) ◽  
pp. 1057-1068
Author(s):  
Hui Peng ◽  
Juhong Tie ◽  
Dequan Guo
Keyword(s):  
Poisson’S Ratio ◽  
Signal To Noise Ratio ◽  
Lateral Displacement ◽  
Axial Strain ◽  
Poisson's Ratio ◽  
Lateral Strain ◽  
Signal To Noise ◽  
Strain Estimation ◽  
Rf Signals ◽  
Noise Ratio

Conventional ultrasound strain imaging usually only calculates the axial strain. Although axial strain is the main component of two dimensional strain field, lateral displacement and strain estimation can provide additional information of human mechanical properties. Shear strain and Poisson’s ratio can be estimated by using lateral strain estimation technique. Low lateral sampling rate and decorrelation noise of lateral radio frequency (RF) signal caused by axial displacement motion increase the difficulty of lateral strain estimation. Subband division technique is to divide a broadband signal into several narrowband signals. In this paper, the application of subband division technique in axial and lateral strain estimation is studied, and an iterative method for estimating axial and lateral strains is proposed based on subband technique. The subband division of this method is carried out along the axial direction, so that the bandwidth of the lateral subband signal is maintained and the quality of the lateral sub strain image is not reduced. In this paper, the number of subbands is three; the compounded lateral strain image is obtained by superimposing these sub strain images on the average. In each iteration, the temporal stretching technique is used to align the axial and lateral RF signals by using the axial and lateral displacement estimation information, which reduces the decorrelation noise of the RF signals. The length of temporal stretching window decreases with the number of iterations, so as to gradually improve the accuracy of temporal stretching. The phase zero algorithm is used to estimate the axial and lateral displacements. The effectiveness of this method is tested by simulations. The simulation results show that the elastographic signal-to-noise ratio (SNRe) of lateral strain image is increased by about 50%, the elastographic contrast noise ratio (CNRe) of lateral strain image is increased by about 120%, the SNRe of axial strain image is increased by about 4%, the CNRe of axial strain image is increased by 8%, and the signal-to-noise ratio of Poisson’s ratio image is increased by about 40%.

In Situ Measurement of Poisson’s Ratio of Steel Plates During Thermal Processes Using Resonant Modes

2021 ◽  
Author(s):  
Clemens Grünsteidl ◽  
Christian Kerschbaummayr ◽  
Edgar Scherleitner ◽  
Bernhard Reitinger ◽  
Georg Watzl ◽  
...  
Keyword(s):  
Poisson’S Ratio ◽  
Dual Phase Steel ◽  
Steel Plates ◽  
Poisson's Ratio ◽  
Austenitic Phase ◽  
Resonant Modes ◽  
Longitudinal Sound Velocity ◽  
Contact Free

Abstract We demonstrate the determination of the Poisson’s ratio of steel plates during thermal processing based on contact free laser ultrasound measurements. Our method utilizes resonant elastic waves sustained by the plate, provides high amplitudes, and requires only a moderate detection bandwidth. For the analysis, the thickness of the samples does not need to be known. The trend of the measured Poisson’s ratio reveals a phase transformation in dual-phase steel samples. While previous approaches based on the measurement of the longitudinal sound velocity cannot distinguish between the ferritic and austenitic phase above 770°C, the shown method can. If the thickness of the samples is known, the method also provides both sound velocities of the material. The gained complementary information could be used to analyze phase composition of steel from low temperatures up to its melting point.

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