Polarization method for the determination of Poisson’s ratio in boreholes

Geophysics ◽  
1985 ◽  
Vol 50 (12) ◽  
pp. 2808-2816
Author(s):  
T. W. Spencer ◽  
Ru Chuan Wu
Keyword(s):  
Poisson’S Ratio ◽  
Shear Velocity ◽  
Poisson's Ratio ◽  
Head Wave ◽  
Velocity Measurements ◽  
Polarization Method ◽  
Full Waveform ◽  
Sensitive Function ◽  
Sonic Logs

Conventional methods for determining Poisson’s ratio from full‐waveform sonic logs rely on measurement of the shear velocity. This measurement is subject to significant error from contamination by events which do not travel at the shear velocity; it fails in soft formations where the shear head wave and pseudo‐Rayleigh waves are not excited. A new method is presented for determining Poisson’s ratio and shear velocity. This method can be implemented by recording the components of particle displacement on the borehole wall. The particle trajectory in the compressional head wave is rectilinear and is deflected with respect to the direction of propagation. The deflection is a sensitive function of Poisson’s ratio, varying by more than 30 degrees over the range of Poisson’s ratios encountered in rocks. In the polarization method all the measurements are made on the compressional head wave, the spatial resolution is greater than for velocity measurements, and the deflection is greatest in soft formations.

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.

Determination of poisson's ratio for polyimide films

1989 ◽  
Vol 29 (16) ◽  
pp. 1107-1110 ◽  
Author(s):  
C. L. Bauer ◽  
R. J. Farris
Keyword(s):  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Polyimide Films

scholarly journals Temperature Variability of Poisson’s Ratio and Its Influence on the Complex Modulus Determined by Dynamic Mechanical Analysis

Technologies ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 81
Author(s):  
Vitor Carneiro ◽  
Helder Puga
Keyword(s):  
Dynamic Mechanical Analysis ◽  
Poisson’S Ratio ◽  
Complex Modulus ◽  
Mechanical Analysis ◽  
Temperature Variability ◽  
Poisson's Ratio ◽  
Constant Frequency ◽  
Dynamic Mechanical ◽  
Characterization Of Materials

Dynamic mechanical analysis (DMA) is the usual technology for the thermomechanical viscoelastic characterization of materials. This method monitors the instant values of load and displacement to determine the instant specimen stiffness. Posteriorly, it recurs to those values, the geometric dimensions of the specimen, and Poisson’s ratio to determine the complex modulus. However, during this analysis, it is assumed that Poisson’s ratio is constant, which is not always true, especially in situations where the temperature can change and promote internal modification in the specimens. This study explores the error that is imposed in the results by the determination of the real values of complex moduli due to variable Poisson’s ratios arising from temperature variability using a constant frequency. The results suggest that the evolution of the dynamic mechanical analysis should consider the Poisson’s ratio input as a variable to eliminate this error in future material characterization.

Tables for Frequencies and Modes of Free Vibration of Infinitely Long Thin Cylindrical Shells

1954 ◽  
Vol 21 (2) ◽  
pp. 178-184
Author(s):  
M. L. Baron ◽  
H. H. Bleich
Keyword(s):  
Free Vibration ◽  
Poisson’S Ratio ◽  
Cylindrical Shells ◽  
Bending Stiffness ◽  
Poisson's Ratio ◽  
Underlying Theory ◽  
Half Wave ◽  
Quick Determination ◽  
Circumferential Waves

Abstract Tables are presented for the quick determination of the frequencies and shapes of modes of infinitely long thin cylindrical shells. To make the problem tractable, the shells are first treated as membranes without bending stiffness, and the bending effects are introduced subsequently as corrections. The underlying theory is based on the energy expressions for cylindrical shells. The tables cover the following range: lengths of longitudinal half wave L from 1 to 10 radii a; number n of circumferential waves from 0 to 6. The results apply for Poisson’s ratio ν = 0.30.

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