Uniaxial Strain Tests Research Articles

Loading Rate Effects on Compressibility of Sand

Stress-strain curves from 61 uniaxial strain tests are presented which depict the response of three dry sands to intense transient pressures; the loadings ranged from 10 MPa to 80 MPa and were applied with rise times ranging from a few tenths of a millisecond to a few minutes. Equipment and techniques used to conduct the tests and to assess the effect of wave propagation on the measurements are described. The data show that the resistance of dry sands to compression increases dramatically when loading rise times are less than 1 msec, and that the character of the stress-strain relation shifts rapidly from a stiffening response (curvature concave to stress axis) to a softening response (curvature concave to strain axis). The stress-strain response of a relatively simple rate-dependent rheologic model is shown to be in good agreement, both qualitatively and quantitatively, with the measured results.

MEASUREMENTS OF THE LONGITUDINAL MODULUS OF PIERRE CLAY SHALE AT VARYING STRAIN RATES

The propagation speed of finite‐amplitude compressional waves of strain‐rate [Formula: see text] in Pierre clay shale have been measured using shock wave techniques. The inferred longitudinal modulus perpendicular to the bedding is approximately a factor of four higher than that measured by others in uniaxial strain tests at strain rates of [Formula: see text]. The present shock wave speeds measured in the laboratory and in‐situ finite‐amplitude explosive experiments measured by others correlate more closely with field seismic velocities than with laboratory uniaxial strain measurements. Elastic properties of this highly saturated friable material measured parallel to the bedding are less sensitive to sampling disturbances than those measured in the perpendicular direction.

A comparison of quasi-static uniaxial-strain and hugoniot tests for quartz-phenolic composite

The purpose of this paper is to show that, within experimental uncertainty, the change in volume with stress obtained by quasi-static uniaxial-strain tests matches that obtained by hugoniot experiments over the same pressure range for quartz phenolic. The result of these tests shows that comparing the data by both techniques is meaningful. In addition, the use of the relatively simple and inexpensive quasi-static uniaxial-strain test (strain rates of 10−4/sec) may provide designers and materials engineers a method for rapid surveying of materials for their hugoniot properties.

Analysis of laboratory test data to derive soil constitutive properties: J.G. Jackson, Jr. 39 pp (Apr. 1969).

Abstract : Computer codes used in the solution of free-field ground shock problems are based on mathematically defined constitutive models. Quantitative input for these constitutive models is primarily based on laboratory test data, but extensive analysis and numerous assumptions are required to convert these data to a form suitable for actual code input. This report presents a detailed illustration of the analyses involved in deriving the soil constitutive properties required for a specific code formulation using laboratory test data from just one stratum of a single site. Data are available from static and dynamic uniaxial strain and triaxial shear tests; code property requirements are for mathematical expressions relating mean pressure to volumetric strain, Poisson's ratio to mean pressure, and a plastic yield criterion to mean pressure. The illustration indicates that progress is being made in developing mathematical constitutive models that are realistic in terms of actual physical behavior, but that if many of the assumptions presently being made in soil property analyses are to be eliminated, additional soil tests and measurements must be developed.

Report on New Experiments with Super-conductors : H. Kamerlingh Onnes (Communications, Phys. Lab., Leyden, Supplement No. 50.)

Bending tolerance is one of the most fundamental mechanical properties of REBCO coated conductors for application to a superconducting coil. In this study, we investigated critical current degradation of REBCO coated conductors under bending and uniaxial tensile strain at 77 K and self-field with three different kinds of production from SuperPower Inc, Suzhou Advanced Materials Research Institute (SAMRI) and Shanghai Superconductor Technology (STT), respectively. All the tapes showed better bending tolerance under compressive strain than tensile strain, particularly for STT tapes, which showed no Ic degradation in compressive bending strain even with bending radius of 4.5 mm, but a 5% Ic degradation in tensile strain with bending radius of 6–6.5 mm. A uniaxial tensile strain test was also carried out to verify the dependence of Ic under tensile bending strain, the test results showed a good agreement between them. The tensile strain tolerance was 0.28–0.29% for STT tapes, 0.4–0.43% for SAMRI tapes, and 0.5–0.55% for SuperPower tapes.