An Experimental Method to Determine Poisson’s Ratio in a Small Beam Subject to Seismic Excitation

1997 ◽  
Author(s):  
Roberto Caracciolo ◽  
Alessandro Gasparetto ◽  
Marco Giovagnoni
Keyword(s):  
Experimental Method ◽  
Poisson’S Ratio ◽  
Iterative Procedure ◽  
Master Curve ◽  
Seismic Excitation ◽  
Poisson's Ratio ◽  
Strain Gauges ◽  
Frequency Range ◽  
Different Temperatures ◽  
Transverse Strains

Abstract An experimental method to determine Poisson’s ratio in a small beam subject to seismic excitation is presented. Poisson’s ratio is computed by measuring longitudinal and transverse strains by means of electric strain gauges. A first set of tests is carried out with different materials, and it is observed that the measured Poisson’s ratio decreases with frequency. However, to determine whether the observed decrease is true or it is due to an error caused by the plate effect of the beam, a second set of tests at different temperatures is carried out. Then, by applying the reduced variables method, a unique plot for Poisson’s ratio on a much broader frequency range is obtained, which allows to state that the decrease of Poisson’s ratio is true. An iterative procedure is described, which has been developed to gather the curves at different temperatures in a master curve.

Dependence of the Frequency Spectrum of a Circular Disk on Poisson’s Ratio

1957 ◽  
Vol 24 (1) ◽  
pp. 53-54
Author(s):  
R. L. Sharma
Keyword(s):  
Frequency Spectrum ◽  
Poisson’S Ratio ◽  
Circular Disk ◽  
Intermediate Frequency ◽  
Poisson's Ratio ◽  
Axially Symmetric ◽  
Frequency Range ◽  
Flexural Vibrations ◽  
Circular Disks

Abstract The results of computations of frequencies of axially symmetric flexural vibrations of circular disks are given for an intermediate frequency range and for several values of Poisson’s ratio.

An Experimental Method for Determining Poisson’s Ratio of Elastomers

1970 ◽  
Vol 92 (3) ◽  
pp. 381-386 ◽  
Author(s):  
Glenn K. Rightmire
Keyword(s):  
Experimental Method ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Compliant Surface ◽  
Typical Data ◽  
Load Carrying ◽  
The Common ◽  
Significant Figures ◽  
Sensitive Parameters ◽  
Better Than

One of the most important and sensitive parameters defining the characteristic behavior of compliant-surface, fluid-film bearings has been found to be the value of Poisson’s ratio of the elastomer material—a 1 percent variation in ν in the range of common values produces about a 25 percent change in load carrying capacity. Since values of Poisson’s ratio for the common elastomers are unknown with any degree of accuracy, an experimental method has been devised to measure Poisson’s ratio for typical cases to better than four significant figures. This paper describes the method together with an error analysis and typical data from elastomeric samples.

scholarly journals Testing of Auxetic Materials Using Hopkinson Bar and Digital Image Correlation

2018 ◽  
Vol 183 ◽  
pp. 02045 ◽  
Author(s):  
Tomáš Fíla ◽  
Petr Zlámal ◽  
Jan Falta ◽  
Tomáš Doktor ◽  
Petr Koudelka ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Poisson’S Ratio ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Lattice Structure ◽  
Frame Rate ◽  
Image Correlation ◽  
Poisson's Ratio ◽  
Strain Gauges

In this paper, a split Hopkinson pressure bar (SHPB) was used for impact loading of an auxetic lattice (structure with negative Poisson’s ratio) at a given strain-rate. High strength aluminum and polymethyl methacrylate bars instrumented with foil strain-gauges were used for compression of an additively manufactured missing-rib auxetic lattice. All experiments were observed using a high-speed camera with frame-rate set to approx. 135.000 fps. High-speed images were synchronized with the strain-gauge records. Dynamic equilibrium in the specimen was analyzed and optimized pulse-shaping was introduced in the selected experiments. Longitudinal and lateral in-plane displacements and strains were evaluated using digital image correlation (DIC) technique. DIC results were compared with results obtained from strain-gauges and were found to be in good agreement. Using DIC, it was possible to analyze in-plane strain distribution in the specimens and to evaluate strain dependent Poisson’s ratio of the auxetic structure.

Direct measurement and master curve construction of viscoelastic Poisson's ratio with digital image correlation

Strain ◽  
2018 ◽  
Vol 54 (6) ◽  
pp. e12294 ◽  
Author(s):  
Yusuke Hoshino ◽  
Kazuki Tamai ◽  
Yuelin Zhang ◽  
Satoru Yoneyama
Keyword(s):  
Digital Image Correlation ◽  
Direct Measurement ◽  
Digital Image ◽  
Poisson’S Ratio ◽  
Master Curve ◽  
Image Correlation ◽  
Poisson's Ratio

Time- and Temperature-Dependent Thermo-Mechanical Modeling of a Packaging Molding Compound and its Effect on Packaging Process Stresses

2003 ◽  
Vol 125 (4) ◽  
pp. 539-548 ◽  
Author(s):  
L. J. Ernst ◽  
G. Q. Zhang ◽  
K. M. B. Jansen ◽  
H. J. L. Bressers
Keyword(s):  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Tensile Creep ◽  
Model Parameters ◽  
Elastic Model ◽  
Large Variability ◽  
Molding Compound ◽  
Packaging Process ◽  
Molding Compounds ◽  
Different Temperatures

For reliable virtual thermo-mechanical prototyping of electronic packages appropriate descriptions of the mechanical behavior of the constituent materials are essential. In many packages molding compounds are used for encapsulation and underfill to provide environmental protection and/or to improve the package thermal mechanical reliability. Therefore, among others, the availability of appropriate constitutive models for various epoxy-molding compounds is one of the requirements for computational prototyping. As there is a large variability of available molding compounds, it is essential to be able to experimentally establish the model parameters in an efficient manner. Because of the implied simplicity, linear visco-elastic models combined with the time-temperature superposition theory are mostly used in thermo-mechanical simulations. Among the various experimental possibilities to efficiently establish the model parameter functions, in the present paper the use of unidirectional creep testing is worked out for a chosen molding compound. Here isothermal one-day creep experiments at different temperatures (ranging below and above the glass transition temperature of the compound) are performed. The tensile creep compliance and the time-dependent Poisson’s ratio of the material at different temperatures are successfully used to construct visco-elastic master curves. As the Poisson’s ratio shows a significant change during a creep or relaxation test, its effect in partly constraint situations (as in packages) will be evident. Therefore it is not reliable to approximate this variable using a constant value. Further, the visco-elastic model of the material is implemented in a finite element program and verified by means of a shear stress relaxation experiment and a creep experiment both under nonisothermal conditions. Moreover, the effect of the creep behavior of the molding compound on the packaging process stress field and its evolution is investigated. Substantial cost saving was realized by package design optimization based on the reliable prediction of the packaging process stresses.

scholarly journals Continuous measurement of apparent Poisson’s ratio for yarn based on omni-directional diameters

2016 ◽  
Vol 87 (6) ◽  
pp. 739-746 ◽  
Author(s):  
Masayuki Takatera ◽  
Tamotsu Arichi ◽  
Julie Peiffer ◽  
Chunhong Zhu ◽  
KyoungOk Kim
Keyword(s):  
Poisson’S Ratio ◽  
Longitudinal Strain ◽  
Poisson's Ratio ◽  
Transverse Strain ◽  
Tensile Tester ◽  
Fiber Packing Density ◽  
Spun Yarns ◽  
The Mean ◽  
Transverse Strains ◽  
The Relationship

We proposed a new method for measuring apparent Poisson’s ratio for yarn and developed a new tensile tester equipped with a digital micrometer that can measure the omni-directional diameter of the yarn annularly while the yarn is elongated. Values of apparent Poisson’s ratio were obtained from the longitudinal and transverse strains continuously. The mean diameter measured omni-directionally was used to calculate the transverse strain for each longitudinal strain. We tested five spun yarns, one monofilament yarn and two filament yarns and obtained values of apparent Poisson’s ratio against longitudinal strain for all samples. Apparent Poisson’s ratio was not constant for spun and filament yarns, while it was constant for monofilament yarn. When the longitudinal strain was low, apparent Poisson’s ratios of ring spun yarns and filament yarns were large, owing to the fiber packing density. As the longitudinal strain increased, apparent Poisson’s ratio gradually decreased. Furthermore, we approximated the relationship between apparent Poisson’s ratio and the longitudinal strain using a power function. The apparent Poisson values can be used in the simulation of fabrics.

scholarly journals MEASURING THE DYNAMIC POISSON'S RATIO OF WOOD WITH THE USE OF A RADIO INTERFEROMETER

2020 ◽  
Vol 82 (4) ◽  
pp. 413-427
Author(s):  
V.V. Balandin ◽  
Vl.Vl. Balandin ◽  
A.K. Lomunov ◽  
V.V. Parkhachev
Keyword(s):  
Lateral Surface ◽  
Poisson’S Ratio ◽  
Compressive Load ◽  
Poisson's Ratio ◽  
Radio Interferometer ◽  
Strain Gauges ◽  
Air Humidity ◽  
Split Hopkinson ◽  
Lateral Displacements ◽  
Base Strain

A new method is proposed for determining the dynamic Poisson's ratio of both isotropic and anisotropic materials. The sample was loaded with a pulsed compressive load on a setup that implements the Kolsky technique using a split Hopkinson bar. The development in time of the longitudinal compressive deformation of the sample was determined by the signals recorded with the help of low-base strain gauges glued to the measuring bars. A millimeter-wave interferometer was used to measure the development of the radial components of the sample deformation in time. To assess the possible asymmetry of the radial expansion of the sample, measurements were carried out using two independent channels irradiating diametrically opposite zones of the lateral surface of the sample. The tests were carried out on a sample of pine with air humidity in the form of a cylinder 54 mm in diameter and 30 mm in height. A pulsed compressive load was loaded along the fibers. Using two channels of the radio interferometer, the separate displacement of the lateral surfaces of the sample was recorded both along and across the annual layers. It was determined that the displacements of the regions of the lateral surface of the sample during expansion along the annual layers are quite close, while during expansion across the annual layers they are very different. The relative transverse deformation of the sample in both cases was determined as the sum of lateral displacements divided by the sample diameter. As a result, two components of the dynamic Poisson's ratio were obtained, which amounted to ~0.2 (in the direction along the annual layers) and ~0.24 (in the direction across the annual layers).

Sign in / Sign up

Export Citation Format

Share Document