Strain Hardening Response of Sintered Porous Iron Tubes With Various Initial Porosities Under Combined Tension and Torsion

1992 ◽  
Vol 114 (2) ◽  
pp. 213-217 ◽  
Author(s):  
K. T. Kim ◽  
Y. S. Kwon
Keyword(s):  
Experimental Data ◽  
Plastic Strain ◽  
Strain Hardening ◽  
Constitutive Equations ◽  
Yield Function ◽  
Porous Iron ◽  
Constitutive Theories ◽  
Elastic Plastic ◽  
Theoretical Predictions

Elastic-plastic strain hardening responses of sintered porous iron are investigated. By using the yield function of Kim, two sets of constitutive equations are obtained from the constitutive theories by Kim and Suh and by Gurson. Theoretical predictions from these constitutive equations are compared with experimental data for sintered porous iron tubes with various initial porosities under combined tension and torsion.

Bodner-Partom Constitutive Model and Nonlinear Finite Element Analysis

1990 ◽  
Vol 112 (3) ◽  
pp. 287-291 ◽  
Author(s):  
F. A. Kolkailah ◽  
A. J. McPhate
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Plastic Strain ◽  
Constitutive Model ◽  
Finite Element Model ◽  
Numerical Technique ◽  
Element Model ◽  
Material Behavior ◽  
Model Parameters ◽  
Elastic Plastic

In this paper, results from an elastic-plastic finite-element model incorporating the Bodner-Partom model of nonlinear time-dependent material behavior are presented. The parameters in the constitutive model are computed from a leastsquare fit to experimental data obtained from uniaxial stress-strain and creep tests at 650°C. The finite element model of a double-notched specimen is employed to determine the value of the elastic-plastic strain and is compared to experimental data. The constitutive model parameters evaluated in this paper are found to be in good agreement with those obtained by the other investigators. However, the parameters determined by the numerical technique tend to give response that agree with the data better than do graphically determined parameters previously used. The calculated elastic-plastic strain from the model agreed well with the experimental strain.

Ductile Tearing Instability of a Center-Cracked Panel of an Elastic-Plastic Strain Hardening Material

1981 ◽  
Vol 103 (1) ◽  
pp. 46-54 ◽  
Author(s):  
Akram Zahoor ◽  
Paul C. Paris
Keyword(s):  
Plastic Strain ◽  
Strain Hardening ◽  
Plane Strain ◽  
Plane Stress ◽  
Hardening Material ◽  
Ductile Tearing ◽  
Elastic Plastic ◽  
Linear Elastic ◽  
Tearing Instability ◽  
Crack Stability

An analysis for crack instability in an elastic-plastic strain hardening material is presented which utilizes the J-integral and the tearing modulus parameter, T. A center-cracked panel of finite dimensions with Ramberg-Osgood material representation is analyzed for plane stress as well as plane strain. The analysis is applicable in the entire range of elastic-plastic loading from linear elastic to full yield. Crack instability is strongly influenced by the elastic compliance of the system, the conditions of plane stress or plane strain, and the hardening characteristics of the material. Numerical results indicate that if crack stability is ensured in a plane strain situation, then under the same circumstances a geometrically identical but plane stress panel will be stable.

Plastic Buckling of Torispherical and Ellipsoidal Shells Subjected to Internal Pressure

1981 ◽  
Vol 195 (1) ◽  
pp. 329-345 ◽  
Author(s):  
G D Galletly
Keyword(s):  
Stainless Steel ◽  
Internal Pressure ◽  
Strain Hardening ◽  
Design Procedure ◽  
Experimental Results ◽  
Elastic Plastic ◽  
Theoretical Predictions ◽  
The Usa ◽  
Simplifying Assumptions ◽  
The Uk

Thin metallic torispherical shells are used frequently in many industries as end closures on cylinders subjected to internal pressure and, for those torispheres which have diameter/thickness ratios greater than 400, elastic-plastic internal pressure buckling may occur. As yet, however, code rules to assist the designer with this buckling problem are not available in either the UK or the USA and one of the aims of this paper is to help to correct this situation. Elastic-plastic internal buckling pressures, for a range of perfect torispherical geometries and obtained with the aid of a sophisticated computer program, are given in the first part of the paper. These pcr's are then utilized (a) to develop a relatively simple equation for predicting the internal buckling pressures of torispherical shells and (b) to assess the accuracy of another, even simpler, approximate buckling equation which was suggested recently (1). Next, the correlation between the theoretical predictions of pcr and the experimental results is considered. The tests taken into account were (a) 5 in diameter machined model torispherical shells, (b) 20 in diameter spun ellipsoidal shells, and (c) 54 in diameter pressed and spun torispherical shells. The shells in (b) and (c) were not stress-relieved and a number of them were made from strain-hardening materials. The agreement between theory and experiment was good for the machined models and fairly satisfactory for the spun models. For the ellipsoidal shells there was also reasonably good agreement between the predictions of two simple design equations and the experimental results. The problems associated with the prediction of the internal buckling pressures of spun torispherical shells made from strain-hardening materials (e.g. stainless steel) are considered in the last section of the paper. Taking the results of the previous sections of the paper into account, and making some simplifying assumptions, a tentative design procedure for predicting the pcr's of these ‘as-manufactured’ spun torispherical shells is proposed. This procedure is then checked by comparing its predictions with experimental buckling pressures found for eleven spun stainless steel heads and six crown and segment ones. The agreement between experiment and theory was quite satisfactory and it is hoped that the suggested procedure might become the first step towards the development of experimentally validated code rules for preventing the occurrence of buckling in these dished ends.

Elastic-Plastic Response of Sintered Porous Iron Under Uniaxial Strain Cycling

1993 ◽  
Vol 115 (1) ◽  
pp. 89-94 ◽  
Author(s):  
K. T. Kim ◽  
Y. S. Kwon
Keyword(s):  
Constitutive Equations ◽  
Uniaxial Strain ◽  
Porous Iron ◽  
Plastic Response ◽  
Elastic Plastic ◽  
Plastic Responses ◽  
Theoretical Results ◽  
Strain Cycling ◽  
Cyclic Data

Elastic-plastic responses of porous iron under uniaxial strain cycling between two fixed values of strain are investigated. A special set of constitutive equations is formulated by including isotropic, kinematic and saturation hardening responses. The theoretical results from the constitutive equations are compared with experimental cyclic data for porous iron, with various porosities.

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