Complete experimental solution of three-dimensional elastic problems

1975 ◽  
Vol 10 (1) ◽  
pp. 42-52 ◽  
Author(s):  
A J Durelli
Keyword(s):  
Optical Properties ◽  
Critical Temperature ◽  
Poisson’S Ratio ◽  
Three Dimensional ◽  
Poisson's Ratio ◽  
Strain Measurements ◽  
Complete Determination ◽  
Photoelastic Data ◽  
Moire Method

The mechanical and optical properties of a transparent epoxy are described, the response of which can be ‘locked-in’ at a critical temperature. The Poisson's ratio of this material is about 0.4, which is closer to the Poisson's ratio of common engineering materials than is that of the commonly used epoxies. Since the material is compressible, strain measurements on relaxed slices permit the complete determination of the stress field. Examples of applications to a solid and hollow sphere and to a tube, subjected to diametral compression, are given. The method permits the solution of three-dimensional problems by use of (1) photoelastic data only, (2) the moiré method only, or (3) mechanically obtained data only, or different combinations of them.

scholarly journals On relevance of time-dependent Poisson’s ratio for determination of relaxation function parameters

2019 ◽  
Vol 41 (11) ◽  
Author(s):  
Cyprian Suchocki ◽  
Rafał Molak
Keyword(s):  
Poisson’S Ratio ◽  
Relaxation Function ◽  
Memory Function ◽  
Viscoelastic Model ◽  
Three Dimensional ◽  
Acrylonitrile Butadiene Styrene ◽  
Time Dependent ◽  
Poisson's Ratio ◽  
Viscoelastic Constants

Abstract The current study concerns the determination of material constants of a three-dimensional linear viscoelastic model. It is assumed that the constitutive equation utilizes a Prony series as a memory function. A method for the evaluation of relaxation function parameters is presented which can be used for arbitrary loading histories. The proposed methodology is applied to the identification of the viscoelastic constants of acrylonitrile butadiene styrene (ABS). For that purpose, a number of rheological tests in tension have been performed on ABS standard dogbone specimens. The significance of the time-dependent Poisson’s ratio for the determination of material parameters is investigated. It is found that taking into account the measurements of specimen’s lateral contraction over time has a particularly strong influence on the identified values of parameters responsible for the bulk behavior. Several boundary value problems have been analyzed in order to assess the influence of the material parameter values on the obtained solutions. It is demonstrated that some oversimplifications assumed during the determination of viscoelastic constants can lead to a loss of precision or even wrong results.

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.

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