Increase of Stress With Permanent Strain and Stress-Strain Relations in the Plastic State for Copper Under Combined Stresses

1943 ◽  
Vol 10 (4) ◽  
pp. A187-A196
Author(s):  
E. A. Davis
Keyword(s):  
Internal Pressure ◽  
Axial Load ◽  
Plastic State ◽  
Plastic Strains ◽  
Permanent Strain ◽  
Axial Tension ◽  
Combined Stresses ◽  
Hollow Cylinders ◽  
Annealed Copper ◽  
Principal Strains

Abstract Annealed-copper specimens in the shape of hollow cylinders have been tested by subjecting them to combined axial tension and internal pressure. A given ratio of the internal pressure to the axial load has been maintained throughout each test, but for different tests this ratio was changed so as to cover the range from pure tension at one extreme to the case of equal biaxial tensions at the other. The results have been used to study the manner in which the plastic strains increase with increasing stress and also to determine the relationships between the three principal strains at any instant during the test. Also, a few observations are made on the types of fracture obtained under various conditions of loading.

Anisotropic Loading Functions for Combined Stresses in the Plastic Range

1955 ◽  
Vol 22 (1) ◽  
pp. 77-85
Author(s):  
L. W. Hu ◽  
Joseph Marin
Keyword(s):  
Plastic Flow ◽  
Biaxial Tension ◽  
Strain History ◽  
Test Results ◽  
Axial Tension ◽  
State Of Stress ◽  
Loading Function ◽  
Combined Stresses ◽  
Shift Of Origin ◽  
Tubular Specimens

Abstract A loading function is a relation between combined stresses for which the beginning of plastic flow takes place. The loading function for a given material is different depending upon the initial plastic strains produced. That is, the initial stress or strain history influences the subsequent loading function. This paper gives the results of an experimental investigation to determine the validity of certain loading functions proposed for anisotropic materials. The study reported was conducted for an aluminum alloy 24S-T and the state of stress covered was biaxial tension. These stresses were produced in the usual way by subjecting thin-walled tubular specimens to axial tension and internal pressure. The test results showed that none of the existing loading functions is adequate for interpreting the plastic stress-strain relations obtained. Tests also were made to determine the change in the loading function with increase in plastic flow. It was found that the loading function did not remain symmetrical with respect to the original function, nor was the new loading function the same as the original except for a shift of origin. However, the test results support in a qualitative way the concept of the so-called “yield corner.”

The Effect of Length: Diameter Ratio on Collapse of Casing

1984 ◽  
Vol 106 (2) ◽  
pp. 160-165 ◽  
Author(s):  
N. C. Huang ◽  
P. D. Pattillo
Keyword(s):  
Axial Load ◽  
External Pressure ◽  
Field Application ◽  
Diameter Ratio ◽  
Finite Cylinder ◽  
Oil Well ◽  
Steel Mill ◽  
Cross Sectional ◽  
Axial Tension ◽  
Collapse Resistance

This paper presents an analysis of the cross-sectional collapse of a cylinder of finite length loaded simultaneously by an axial tension (which may be zero) and external pressure. The calculation is based on Sanders’ nonlinear shell equations with plasticity introduced via the concept of effective stress from a uniaxial tension test. The finite cylinder is an appropriate model of oil well casing as it undergoes quality control testing in the steel mill where the edges of the cylinder are usually fixed in the case of nonzero axial load and free in the case of zero axial load. However, in field application, the length: diameter ratio of casing is such that the cylinder may be considered infinite. Guidelines contained herein permit prediction of the collapse resistance of field casing from the results of mill tests performed on short samples.

scholarly journals The theory of combined plastic and elastic deformation with particular reference to a thick tube under internal pressure

1947 ◽  
Vol 191 (1026) ◽  
pp. 278-303 ◽  
Keyword(s):  
Stress Distribution ◽  
Internal Pressure ◽  
Plastic Flow ◽  
Plastic Region ◽  
Strain Diagram ◽  
Combined Stresses ◽  
Usual Theory ◽  
Plastic Components ◽  
Longitudinal Extension ◽  
Elastic Strains

In certain problems of plastic flow, for example, a thick tube expanded by internal pressure, it is important to consider changes in the elastic strain of material which is flowing plastically in order to deduce the correct stress distribution and deformation. The usual plastic theory which neglects elastic strains in the plastic region may lead to considerable errors in certain cases. In this paper we review the theory of the deformation of a material under combined stresses which involves both elastic and plastic components of strain. The relationship between stress and strain is represented on a plane diagram, the reduced stress-strain diagram, which facilitates discrimination between the elastic and plastic components of strain and aids considerably the solution of certain problems. The diagram can also be used to express the relationships governing the dissipation of energy during plastic flow under combined stresses. The theory is applied to the deformation of a long thick tube under internal pressure with zero longitudinal extension. The solution is compared with that based on the usual theory which neglects elastic strains in the plastic region, revealing an error which reaches a maxi­mum of over 60% in the longitudinal stress distribution. The significance of the differences between the two solutions is discussed in detail.

Axisymmetric Stress Analysis and Strength Evaluation of Bonded Shrink Fitted Joints of Circular Pipes Subjected to Internal Pressure and Tensile Loads

2000 ◽  
Author(s):  
Masahide Katsuo ◽  
Toshiyuki Sawa ◽  
Masahiro Yoneno
Keyword(s):  
Internal Pressure ◽  
Stress Analysis ◽  
Joint Strength ◽  
Tensile Load ◽  
Theory Of Elasticity ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Strength Evaluation ◽  
Circular Pipes ◽  
Hollow Cylinders

Abstract This study deals with the stress analysis and the strength evaluation of a bonded shrink fitted joint of circular pipes subjected to an internal pressure and a tensile load. In the analysis, two pipes and the adhesive are replaced with finite hollow cylinders, and the stress distributions in the joint are analyzed by using the axisymmetric theory of elasticity. From the numerical calculations, the following results are obtained: (1) Both the compressive and shear stresses at the interface between the adherend and the adhesive increase as Young’s modulus of the adherend increases. (2) The stress becomes singular at the edges of the interfaces. (3) The joint strength can be evaluated using the compressive and shear stresses near the edge of the interface. In the experiments, bonded shrink fitted joints consisting of dissimilar circular pipes were manufactured, and rupture tests of the joints were carried out by applying an internal pressure, and a tensile load to the joints. From the results, the joint strength of the bonded shrink fitted joint was found to be greater than that of the shrink fitted joint. Furthermore, the numerical results are in fairly good agreement with the experimental ones.

On the Response of Elastic-Plastic Tubes Under Combined Bending and Tension

1992 ◽  
Vol 114 (1) ◽  
pp. 50-62 ◽  
Author(s):  
J. Y. Dyau ◽  
S. Kyriakides
Keyword(s):  
Numerical Simulation ◽  
Parametric Study ◽  
Axial Load ◽  
Test Specimen ◽  
Experimental Results ◽  
Two Dimensional ◽  
Plastic Range ◽  
Rigid Surface ◽  
Axial Tension ◽  
Thin Walled

This paper is concerned with the response of long, relatively thin-walled tubes bent into the plastic range in the presence of axial tension. The work is motivated by the design needs of pipelines installed and operated in deep offshore waters. The problem is studied through a combination of experiment and analysis. In the experiments, long metal tubes were bent over a smooth, circular, rigid surface (mandrel). Bending of the tubes was achieved by shear and axial end loads. The experimental arrangement is such that a significant section of the test specimen is loaded and deformed in an axially uniform fashion. The ovalization induced in the specimen was measured as a function of the axial load in the tube for two mandrel radii. A two-dimensional numerical simulation of the problem has been developed and validated against the experimental results. This analysis was used to conduct a parametric study of the effect of tension on the ovalization induced in a long tube during bending.

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