Influence of Ductility on Creep Rupture Under Multiaxial Stresses

1962 ◽  
Vol 84 (2) ◽  
pp. 228-232 ◽  
Author(s):  
W. Sawert ◽  
H. R. Voorhees
Keyword(s):  
Shear Stress ◽  
Internal Pressure ◽  
Maximum Principal Stress ◽  
Creep Rupture ◽  
Principal Stresses ◽  
Relative Response ◽  
Combined Stresses ◽  
Thin Walled ◽  
Tubular Specimens ◽  
Stress Invariant

Creep-rupture times at 1200 and 1400 deg F were compared for notched versus unnotched bars and for thin-walled tubes in uniaxial tension versus combined tension and internal pressure to give a 1:1 ratio of longitudinal and transverse principal stresses. Relative response to multiaxial stresses of cast DCM alloy with low ductility was not essentially different from that of Rene´ 41 alloy with higher ductility. Creep rupture times of the tubular specimens under combined stresses correlated better in terms of the shear stress invariant than of maximum principal stress.

Off-Axis Torsion Tests on Tubular Specimens of Steel

2001 ◽  
Vol 123 (3) ◽  
pp. 268-273 ◽  
Author(s):  
Takenobu Takeda ◽  
Zhongchun Chen
Keyword(s):  
Shear Stress ◽  
Yield Stress ◽  
Maximum Shear Stress ◽  
Torsion Test ◽  
Combined Loading ◽  
Anisotropic Hardening ◽  
Principal Stresses ◽  
Maximum Value ◽  
The Difference ◽  
Tubular Specimens

In order to analyze the anisotropic hardening behavior of metals, an off-axis torsion test by combined loading is developed. In this test, the maximum shear stress direction φ can be changed from 0 deg to 90 deg while the ratio of maximum and minimum principal stresses is kept at −1. With increasing angle φ, the yield stress of the torsional-prestrained steel decreases; the difference between the directions of the maximum shear stress and principal shear strain increment rises to a maximum value and then decreases. It is experimentally verified that anisotropy is more severe when a smaller offset strain is used in defining the yield stress.

Creep Rupture Tests for Design of High-Pressure Steam Equipment

1960 ◽  
Vol 82 (2) ◽  
pp. 453-461 ◽  
Author(s):  
E. A. Davis
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
Internal Pressure ◽  
Strain Rate ◽  
Uniaxial Tension ◽  
Effective Strain ◽  
Creep Rupture ◽  
Tension Tests ◽  
Pressure Steam ◽  
Tubular Specimens

Creep rupture tests on tubular specimens of type 316 stainless steel were run at 1200 F and at pressures up to 24,000 psi. The specimens were tested under pure internal pressure and equal biaxial tensions. The results of these tests correlate favorably with those of uniaxial tension tests if a comparison is made on the basis of effective stress and effective strain rate.

Biezeno Pressure Vessel Heads

1956 ◽  
Vol 23 (4) ◽  
pp. 642-645
Author(s):  
R. A. Struble
Keyword(s):  
Shear Stress ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Maximum Shear Stress ◽  
Head Shape ◽  
Thin Walled ◽  
Constant Maximum

Abstract The equation of thin-walled pressure vessel heads with constant maximum shear stress throughout is derived. Such heads, used on cylindrical vessels with uniform internal pressure, were first conceived by Biezeno in 1922 who gave a semigraphical prescription for determining the head shape.

Stresses in the experiments with loading tubular specimens by internal pressure

2020 ◽  
Vol 86 (12) ◽  
pp. 64-68
Author(s):  
N. N. Tormakhov
Keyword(s):  
Mechanical Properties ◽  
Internal Pressure ◽  
Middle Surface ◽  
Plastic State ◽  
Elastic State ◽  
Tubular Specimen ◽  
Inner Surface ◽  
Thin Walled ◽  
Tubular Specimens

When using different formulas for determination of axial and circumferential stresses in the experiments on loading thin-walled tubular specimens with internal pressure the radial stresses are neglected due to their smallness. We propose a novel procedure for determining stresses in the internal pressure loaded thin-walled tubular specimens. The distribution of stresses in the radial direction of a tubular specimen is studied both for the elastic state and for perfectly plastic state according to the Huber – von Mises criterion of an incompressible material. It is shown that the degree of heterogeneity of the stress state depends on the ratio of the wall thickness to the specimen diameter and on the elastic or plastic state of the material. The circumferential stresses are maximal on the inner surface of the specimen and the axial stresses are constant along the radius of the specimen in the elastic state, whereas in the plastic state circumferential and axial stresses are maximal on the outer- and inner surface of the specimen, respectively. The distributions of radial stresses in the elastic and plastic state of the material are almost identical, i.e., both are maximal on the inner surface and equal to zero on the outer surface of the specimen. The values of circumferential and axial stresses on the middle surface of a thin-walled tubular specimen normalized to the internal pressure almost do not depend on the elastic or plastic state of the specimen material thus providing a basis for determination of the mechanical properties of the material from the stress-strain state of the middle surface of the specimen using the Lame formulas for stress calculations. When determining the stress intensity, it is desirable to take into account the radial stresses, since it increases the accuracy of determining the mechanical properties of the material and reduces the sampling range of the yield point for different types of the stress state.

Finite element investigation into the torsion test in the range of large strains and deformations

2001 ◽  
Vol 36 (4) ◽  
pp. 401-409
Author(s):  
X Peng ◽  
Y Qin ◽  
R Balendra
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Shear Strain ◽  
Twist Angle ◽  
Large Strains ◽  
End Effect ◽  
Stress Strain ◽  
Strain Relationship ◽  
Thin Walled ◽  
Tubular Specimens

Torsion tests with thin-walled tubular, solid cylindrical and Lindholm-type tubular specimens were simulated using the finite element code ABAQUS, in the range of large strains and deformations. The results showed that for thin-walled tubular and solid cylindrical specimens the radii of the specimens almost remained straight during torsion; for Lindholm-type tubular specimens the twist angle of the cross-section at the two ends of the gauge section did not stay constant, due to the change of the specimen geometry (i.e. the end effect). A correction which considers the end effect should therefore be introduced when the stress-strain relationship is characterized. Compared with the stress-strain relationship obtained previously from experiment, a distinct difference was noted when conventional formulae were used to convert the torque and twist angle into the shear stress and shear strain. Further, the influence of axial constraint conditions at the two ends of the specimen was examined; the results showed that axial strains and stresses had no significant influence on the definition of the shear stress-shear strain relation, and hence these can be neglected when the stress-strain relationship is characterized.

The Stresses in Thick-Walled Cylinders of Mild Steel Overstrained by Internal Pressure

1934 ◽  
Vol 126 (1) ◽  
pp. 407-455 ◽  
Author(s):  
Gilbert Cook
Keyword(s):  
Shear Stress ◽  
Mild Steel ◽  
Internal Pressure ◽  
Wall Thickness ◽  
Maximum Shear Stress ◽  
Internal Surface ◽  
Principal Stresses ◽  
Constant Shear Stress ◽  
Axial Compressive Stress ◽  
Set Up

The paper describes a theoretical and experimental investigation of the stress distribution across the walls of thick cylinders of mild steel when the internal pressure is such that the elastic limit of the material is exceeded and a certain amount of overstrain occurs. The main conclusions are:— (1) That in the cylinders in which it was possible to produce overstrain over the whole wall thickness the observed pressure is in close agreement with that calculated on the assumption of constant shear stress equal to the shear stress observed during plastic yield in tension. (2) That in partially overstrained cylinders the maximum shear stress in the elastic region varies as overstrain proceeds. (3) That at the internal surface the effect of overstrain is to reduce the circumferential tensile stress, and to set up an axial compressive stress. With sufficient wall thickness all three principal stresses at the internal surface become compressive for pressures which still permit of the external portions remaining elastic.

Stress Distributions Around Hydrostatically Loaded Circular Holes in the Neighborhood of Corners

1958 ◽  
Vol 25 (2) ◽  
pp. 178-183
Author(s):  
A. J. Durelli ◽  
A. S. Kobayashi
Keyword(s):  
Shear Stress ◽  
Maximum Shear Stress ◽  
Applied Pressure ◽  
Infinite Plate ◽  
Maximum Principal Stress ◽  
Stress Distributions ◽  
Principal Stresses ◽  
Exterior Boundary ◽  
Hole Radius ◽  
Circular Holes

Abstract The stress distributions around hydrostatically loaded circular holes in the neighborhood of corners was determined by using photoelasticity and brittle coatings. Photoelasticity (by means of a diffused-light polariscope) was used to determine the maximum shear lines (isochromatics), and brittle coatings were used to determine the directions of the principal stresses (isostatics). Tests were conducted for six plates with different ratios of hole radius to hole distance to the exterior boundary of plate (R/L). The results of these tests are presented in the form of curves. These curves show the distribution of the maximum shear stress along the diagonal of the plate, the maximum principal stress along the edges of the plate and of the hole, and the maximum shear stress along a perpendicular line to the exterior boundary drawn from the center of the hole. All these values are given as a function of R/L. Curves also are presented which compare the stresses on the diagonal of the plate at the boundary of the hole with the stresses computed using Lamé’s equation for a thick-walled cylinder. Comparisons also are made with the results obtained by Jeffery for a semi-infinite plate with a circular hole subjected to a hydrostatic pressure. All results are given in dimensionless form with the applied pressure as reference. The results published in this paper are new, but the techniques used have been described previously in papers by researchers from the Armour Research Foundation.

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