Influence of Residual Stress on Fatigue Crack Growth in Thick-Walled Cylinders PDF Download
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Author: A. Stacey
Publisher:
ISBN:
Category : Autofrettage
Languages : en
Pages : 15
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Book Description
An investigation was conducted into fatigue crack growth in samples of as-received and autofrettaged, high-strength, low-alloy steel tubing containing residual stresses. Compact tension and C-shaped and ring specimens were used to measure properties in the axial and radial directions. Internally and externally flawed ring specimens were employed to propagate cracks through the original residual stress field. Experiments were performed for load ratios ranging between -0.5 and 0.8. Fatigue crack growth rates were substantially reduced by compressive residual stresses. The data were corrected for residual stress effects using the superposition principle. An effective stress intensity factor range, ?Keff, was defined that incorporates the residual stress intensity factor, Kres, and the applied ?K range. Using this approach, the correlation with the characteristics for no residual stress was very good. In addition, it was shown that fatigue crack growth rate characteristics measured with C-specimens can significantly misrepresent the actual behavior of the material and tubing under investigation if the remaining residual stress field is not taken into consideration.
Author: A. Stacey
Publisher:
ISBN:
Category : Autofrettage
Languages : en
Pages : 15
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Book Description
An investigation was conducted into fatigue crack growth in samples of as-received and autofrettaged, high-strength, low-alloy steel tubing containing residual stresses. Compact tension and C-shaped and ring specimens were used to measure properties in the axial and radial directions. Internally and externally flawed ring specimens were employed to propagate cracks through the original residual stress field. Experiments were performed for load ratios ranging between -0.5 and 0.8. Fatigue crack growth rates were substantially reduced by compressive residual stresses. The data were corrected for residual stress effects using the superposition principle. An effective stress intensity factor range, ?Keff, was defined that incorporates the residual stress intensity factor, Kres, and the applied ?K range. Using this approach, the correlation with the characteristics for no residual stress was very good. In addition, it was shown that fatigue crack growth rate characteristics measured with C-specimens can significantly misrepresent the actual behavior of the material and tubing under investigation if the remaining residual stress field is not taken into consideration.
Author: Robert L. Champoux
Publisher: ASTM International
ISBN: 0803111959
Category : Fatigue strength (Engineering materials).
Languages : en
Pages : 141
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
This work addresses the influence of Bauschinger effect upon residual stresses and associated fatigue lifetimes for pressurized, autofrettaged thick cylinders. The model employed allows for the variation with radius of Bauschinger Effect Factor (REF) throughout the autofrettaged tube since the percentage plastic strain, which determines BEF, will vary from a maximum value at the bore to zero at the elastic plastic interface. Accounting for BEF variability, it is demonstrated that the residual compressive hoop stress at the inner radius of the tube reaches a maximum value at the percentage overstrain level below which reversed yielding does not occur. Existing experimental residual stress measurements from a variety of sources are shown to support this thesis. This value of overstrain may serve to maximize crack initiation lifetime in autofrettaged thick cylinders. For a tube with significant heat checking and associated initial crack like defects, it is necessary to consider fatigue crack growth rates governed by a crack growth law such as Paris's Law. For a tube of radius ratio 2.0 and at a value of approximately 40 percent overstrain, slightly in excess of that for the onset of reversed yielding, the fatigue lifetime exhibits a maximum value. Fatigue lifetimes achieve a maximum value at overstrain levels in which yielding reaches 1.4 times bore radius and are almost constant thereafter. Furthermore, such extended overstrain leads to a small increase in residual stress at the outside diameter (OD), thus increasing R ratio at that location and reducing fatigue lifetime for crack growth originating at the OD. Existing experimental lifetime measurements are shown to require the inclusion of BEF to properly account for these observed lifetimes.
Author: JA. Kapp
Publisher:
ISBN:
Category : Autofrettage
Languages : en
Pages : 11
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Book Description
A study has been made to investigate the effect of autofrettage on crack growth in externally flawed, thick-walled cylinders and rings. With the use of singular finite elements, stress intensity factors were determined for cylinders containing a single, external crack oriented in the radial direction, subjected to either internal pressure or to a diametrical compression load normal to the crack plane. Fatigue crack growth rate experiments were conducted using several rings cut from cylinders which had been autofrettaged different amounts. The rings were fatigue cycled using the aforementioned compressive loading, which produced a properly oriented external crack. The results of these experiments show that fatigue crack growth rates can be increased by as much as an order of magnitude in cylinders which have been fully autofrettaged over those which contain no residual stresses. There is not sufficient data to model this increase in crack growth rate empirically; however, some comments are given on the effect of autofrettage residual stress on fatigue crack growth rate.
Author: D. P. Kendall
Publisher:
ISBN:
Category :
Languages : en
Pages : 33
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Book Description
A method is proposed for predicting the fatigue life of thick-walled cylinders based on numerical integration of the fatigue crack growth curve as determined from a fracture mechanics analysis. The effects of autofrettage residual stresses, crack shape, and of the compressive portion of the stress intensity factor are accounted for. A method for correcting the autofrettage residual stresses for the Bauschinger Effect, based on recent analytical results by Peter Chen, is also included. A simple computer program for performing the calculation of fatigue life is presented along with a comparison of the calculated results with the experimental results of Davidson, and of Throop and Fujczak.
Author: J. A. Kapp
Publisher:
ISBN:
Category :
Languages : en
Pages : 48
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Book Description
The effect of the autofrettage residual stress distribution on the crack growth rate in externally flawed thick-walled disks has been investigated. The crack growth rate was modeled by using the Paris power law relation. Stress intensity factors were calculated for internally pressurized, externally flawed, non-autofrettaged cylinders, by an approximate technique and with the use of the NASTRAN finite element computer program. A simple experiment was devised to determine the effect of autofrettage on crack growth rate. The test involved diametrically loading thin disks, cut from autofrettaged cylinders, NASTRAN was used to determine the stress intensity factors for this loading geometry. The experimentally observed results show that autofrettage increases the crack growth rate in externally flawed cylinders, but the test did not supply sufficient data to mathematically model the increase. The faster crack growth rate is believed to be caused by the local relaxation of the tensile autofrettage residual stresses due to large plastic zones accompanying crack growth. (Author).
Author: Lennart Josefson
Publisher:
ISBN:
Category :
Languages : en
Pages : 18
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 600
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Book Description
Author: Kee Siong Lian
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Author: A. Niku-Lari
Publisher: Elsevier
ISBN: 1483191001
Category : Science
Languages : en
Pages : 587
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Book Description
Residual Stresses presents a collection of articles that provides information regarding the use of surface treatment systems. It discusses the developments in the technology and application of surface treatment. It addresses the influence of minor stresses on the performance of materials. Some of the topics covered in the book are the introduction to self-equilibrating stresses existing in materials, the stresses that form as a consequence of welding, the stresses made by machining, and the mechanical generation of self-stresses. The analysis of the stresses caused by thermal and thermochemical surface treatments is covered. The minor stresses in composite materials are discussed. The text describes the stresses in uranium and uranium alloys. The Trepan or ring core method, centre-hole method, and Sach's method are presented. A chapter of the volume is devoted to the measurement of residual stresses. Another section of the book focuses on the application of shot peened plates to residual stress distribution. The book will provide useful information to mechanics, engineers, students, and researchers.
