Showing papers on "Hydrostatic stress published in 1974"
TL;DR: In this paper, the fourth-order finite strain expressions for the effective elastic moduli of a solid under hydrostatic stress are derived from a general expression for effective elastic models, which is then written in terms of the moduli and their pressure derivatives evaluated at an arbitrary reference state.
201 citations
TL;DR: In this article, the real area of contact between solids under high contact pressure is examined, and values obtained experimentally are compared with theoretical predictions, and it is demonstrated that material hardness is an important variable; knowledge of initial hardness is not adequate since final contact area depends on final hardness.
20 citations
15 citations
10 citations
TL;DR: In this paper, the axial field parameter D varies linearly with stress and the effect of thermal expansion of the crystal on this parameter was calculated using uniaxial stress EPR experiments.
8 citations
4 citations
Patent•
25 Mar 1974
TL;DR: A hydrostatic stress gage including a sphere of incompressible fluid having positioned inside a drum-like structure containing a pair of interconnected flat spiral coils forming a self-resonant tuned circuit, a change in pressure on the sphere will cause a variation in distance between the coils whereby changing the resonant frequency, when measured by an appropriate device stress may be measured.
Abstract: A hydrostatic stress gage including a sphere of incompressible fluid having positioned inside a drum like structure containing a pair of interconnected flat spiral coils forming a self-resonant tuned circuit, a change in pressure on the sphere will cause a variation in distance between the coils whereby changing the resonant frequency, when measured by an appropriate device stress may be measured.
3 citations
TL;DR: In this article, the authors studied the notch creep rupture strength under torsion for OFHC copper and S 10 C low carbon steel at 200°C and 450°C, respectively.
Abstract: Notch creep rupture strength under torsion was studied for OFHC copper and S 10 C low carbon steel at 200°C and 450°C, respectively. The torsional loading was selected in this study mainly because of several relative merits over the tensile loading from mechanics point of view, such as no existence of the hydrostatic stress component and the negligibility of change in specimen geometry during finite deformation. The results obtained are summarized as follows:(1) Both of the materials investigated, which had previously been found to show “notch-strengthening” under tension, behaved “notch-weakening” under torsion, as was expected from a fracture-mechanics analysis by the authors of notch creep rupture strength under torsion.(2) The mode of crack propagation for the OFHC copper was transgranular in the short life range and intergranular in the medium and long life ranges. For the S 10 C low carbon steel, cracks grew in the transgranular or mixed trans- and intergranular mode. These were essentially the same as those observed under tension.(3) Comparing the results observed under torsion with those under tension, one can conclude that the mechanical plastic constraint of strains induced by the multiaxial tension in the vicinity of the notch root and the contraction of cross-sectional area due to large deformation, particularly in unnotched specimens, are two main causes responsible for “notch-strengthening”; in the lack of these two causes “notch-weakening” prevails.
2 citations
TL;DR: In this article, a theory is developed to explain the effects of hydrostatic pressure on the deformation of cast iron, where it is assumed that a graphite flake in an iron matrix acts as a penny-shaped crack.
Abstract: A theory is developed in this paper to explain the effects of hydrostatic pressure on the deformation of cast iron. It is assumed that a graphite flake in an iron matrix acts as a penny-shaped crack. The external stresses necessary to induce a finite plastic zone near the crack tip are calculated with rough approximation. The analysis provides a qualitative explanation of the following experimental evidences : (1) Superposed hydrostatic pressure increases the flow stress of cast iron. (2) The increase of flow stress due to hydrostatic pressure is reversible with respect to the hydrostatic pressure. (3) Hydrostatic pressure decreases the anisotropy of cast iron usually observed in torsion tests.
2 citations
01 Jan 1974
1 citations
TL;DR: In this paper, the influence of a superimposed hydrostatic pressure on the critical surface expansion during a forging process was investigated, and it was shown that the surface expansion appears to decrease with increasing pressure.
Abstract: One of the most important process parameters in making compound products is the expansion of the bonding surface. Bonding is not obtained until a critical surface expansion, characteristic of the deformation process, is reached. This paper deals with an experimental investigation of the influence of a superimposed hydrostatic pressure on the critical surface expansion during a forging process. The critical surface expansion appears to decrease with increasing hydrostatic pressure. This may be due to the fact that the close contact between the materials necessary to obtain bonding is created by a micro-extrusion of the surfaces into each other. This may explain why the bond strength achieved by different processes, such as forging and extrusion, is quite different for the same value of the surface expansion.