Results Of Biaxial Tests Research Articles

Mechanical Behavior of Sand Reinforced With Mesh Elements

This paper presents a study of the shear strength of sand reinforced with randomly-oriented and vertically-aligned polypropylene mesh elements. A biaxial apparatus was designed to load specimens under plane strain conditions, and photogrammetry was used to measure the strain field within the specimens during loading. The biaxial test results obtained for sand specimens reinforced with randomly-oriented mesh elements illustrate the effect of reinforcement content on specimen strength. Strain localization was observed for both reinforced and unreinforced sand specimens; however, for the reinforced sand specimens, the strain localization phenomenon was not accompanied by a drop in strength. Further testing was performed using a large shear box to impose a fixed shear plane in the reinforced specimens. Sand specimens with randomly-oriented mesh elements, as well as sand reinforced with vertically-aligned mesh elements were tested in the large shear box.

Superplastic gas-pressure deformation of iron carbide sheet

The superplastic flow characteristics of iron carbide under conditions of biaxial gas-pressure forming are described. Forming experiments were conducted a 1050 °C on a fine-grained (7–8 μm) Fe5.25%C-1.5%Cr material. Flow stresses in the range of 6–22 MPa were applied and deformation strain rates approaching 10 −3 s −1 were achieved. The strain distribution in as-formed hemispherical caps was examined for comparison with a previously developed analytical model. Both the stress-strain rate data and the strain analysis show that iron carbide deforms with an apparent strain rate sensitivity exponent value of about 0.4 with deformation rates lower than those observed in uniaxial tensile tests. The difference between uniaxial and biaxial test results is attributable to grain size effects. Microstructural observations and fracture behavior are also discussed.

十字型試験片を用いた高温二軸低サイクル疲労に関する研究

This paper describes the low cycle fatigue behavior of 1Cr-1Mo-1/4V and SUS304 cruciform specimens in wide range biaxial stress conditions of -1.0≤φ≤1.0 at high temperatures, where φ denotes the ratio of the minimum principal strain to the maximum principal strain existing on the specimen surface. The detailed description of the newly developed biaxial fatigue testing machine was made, and the biaxial test results were discussed in connection with the biaxial low cycle fatigue parameter. The COD and ther Γ*-plane parameters were most appropriate to express the biaxial fatigue behavior. Also the X-ray diffraction was made in order to examine the damage in biaxial stress states.

A New Material Model for the Nonlinear Biaxial Behavior of ATJ-S Graphite*

A new model for the deformation behavior of ATJ-S graphite, a non linear transversely isotropic material, under initial loading is described. This material model, which is based on a new deformation theory of ortho tropic plasticity, has excellent potential for description of the biaxial softening phenomenon found in ATJ-S graphite. Biaxial softening is char acterized by the development of larger strains in biaxial tension than in uniaxial tension, in contradiction to conventional Poisson effects. The new model is examined for sensitivity to (1) a nonsymmetric compliance matrix, (2) how the material model constants are obtained, and (3) varia tions in material properties. Comparisons are made between strain values obtained with the material model incorporated in a finite element com puter analysis and strain values from biaxial test results.

Influence of strain rate on mechanical properties of 6061-T6 aluminum under uniaxial and biaxial states of stress

A technique is presented for determining mechanical properties of materials under dynamic tensile loads. A Dynapak metalworking machine was modified into a test fixture capable of producing the required dynamic loads for uniaxial and certain biaxial tensile tests. Results from uniaxial dynamic tests on 6061-T6 aluminum alloy are presented and compared to “static” data obtained from a universal testing machine. The dependence of tensile strength on strain rate and the augmenting effect of temperature on this dependence can be seen. The results of biaxial tests are described in terms of a modified form of the distortion-energy failure theory.