Determination Of Elastic Properties Research Articles

Noninvasive determination of elastic properties and diameter of human limb arteries.

A method involving application of a standard cuff on human limbs has been developed making it possible by a single procedure to make a quantitative determination of blood pressure, elastic resistance of "uninfluenced" an mechanically relaxed arterial vessel walls, their bulk modulus and effective inner diameter. The method which is based on the "elasticity reservoir theory" involves recording arterial pressure recordings during periods of gradual compression and evaluation of the pulsatile blood volume increment under the cuff at the on step wise decompression. The reproducibility of the results and the errors involved were estimated by comparing the results with measurements made on a physical model and on human limbs. This paper presents some results of the application of the method to 113 healthy persons and shows the age dependence of the examined parameters in the upper arms and in the lower leg.

Determination of elastic properties of in situ rocks in permafrost regions : Voronkov, O K; Marov, V I US Army Cold Regions Research and Engineering Lab translation TL 639, July 1977, 18p

Determination of elastic properties of in situ rocks in permafrost regions : Voronkov, O K; Marov, V I US Army Cold Regions Research and Engineering Lab translation TL 639, July 1977, 18p

Modified borehole jack method for elastic property determination in rocks : de la Cruz, R V Rock Mech, V10, N4, April 1978, p221–239

A method is described for the determination of the elastic parameters of rock from in situ tests using friction strain gauge and an extended borehole jack. Tangentially orientated friction strain gauges are positioned on opposite quadrants of the borehole, both other quadrants being fitted with a borehole jack, in order to measure load and deformation simultaneously. Equations are developed from which the modulus of elasticity of the rock mass is obtained. It is shown that a non-uniform pressure distribution and the plate-wall contact area have an insignificant effect on the accuracy of the results. Secondly effects are reduced by carrying out measurements only in the centre of the specimen. This new method has the same advantages as the established Goodman-Jack method. Of great importance is that the theoretical basis is exact. Although the method is only applicable for an ideal elastic material it can also be used for other in situ measurements in addition to the determination of the elastic modulus, for example linearity, anisotropy, inhomogenity, tensile strength and the primary stress condition. (TRRL)

Modified borehole jack method for elastic property determination in rocks

Modified Borehole Jack Method for Elastic Property Determination in Rocks This paper describes a method of determining thein-situ elastic properties of rock masses with friction-strain gauges and a lengthened borehole jack. The method involves impressing tangentially-oriented friction gauges on opposite quadrants of a borehole wall, while the remaining quadrants are loaded by the borehole jack with a unidirectional self-equilibrating pair of forces. The tangential normal strains generated at the borehole wall are thus measured concurrently with the loading. To determine the modulus of the rock mass, equations were developed relating the measured tangential normal strains and the applied ram pressures. Several factors which may influence the interpretation of data were thoroughly analyzed. It was shown that variations in the pressure distribution and area of plate-wall contact have negligible effects on the accuracy of data interpretation. End effects were minimized by lengthening the jack and carrying out strain measurements at the central region only where stresses and strains are homogeneous and plane strain conditions exist. The new method has the same desirable mechanical and operational features as the well-known Goodman-Jack method. Most important, however, its theoretical basis is exact with no estimated coefficients required in the reduction of observed data. While the method requires an ideal elastic material, it has a number of other applications for in-situ measurements besides modulus determination. The modified method could be utilized for determining linearity, anisotropy, inhomogeneity, tensile strength and, with an additional operation, the in-situ stress field.

Ultrasonics in the steel industry

The basic physical principles which underlie the technological developments, although they are not always consciously applied, are briefly outlined. Applications to the detection of internal defects in billets, slabs, plates, tubes, forgings and castings are described. The successful extension of these nondestructive testing techniques to steel at high temperatures has raised a number of problems. The use of ultrasonics to determine the cleanness of steel-the content of inclusions is also under development and extends the scope below the normally recognized limits of detection. The determination of elastic properties and the use of the ultrasonic goniometer are noted

Determination of elastic properties of rock by the pressure tunnel method taking into account rock permeability

Determination of elastic properties of rock by the pressure tunnel method taking into account rock permeability

Plethysmographic in vivo determinations of elastic properties of arteries in man.

Plethysmographic in vivo determinations of elastic properties of arteries in man.

Ultrasonics in geology

Ultrasonics is used in geology for the determination of elastic properties of rocks and minerals. For measurements on rocks, techniques with precisions of a few percent have come into use; these measure delay times of elastic waves propagating through specimens several inches long. For single crystals, the techniques are the same as those used in solid-state physics; they are basically interferometric methods. Techniques of measurement are reviewed. An extensive bibliography is included.