An Experimental-Numerical Determination of the Three-Dimensional Autofrettage Residual Stress Field Incorporating Bauschinger Effects

2005 ◽  
Vol 128 (2) ◽  
pp. 173-178 ◽  
Author(s):  
M. Perl ◽  
J. Perry
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Bauschinger Effect ◽  
Three Dimensional ◽  
Material Behavior ◽  
Numerical Code ◽  
Numerical Magnitude ◽  
Hydraulic Pressure ◽  
Numerical Representation ◽  
Residual Stress Field

Autofrettage of large-caliber gun barrels is used to increase the elastic strength of the tube and is based on the permanent expansion of the cylinder bore, using either hydraulic pressure or an oversized swage mandrel. The theoretical solution of the autofrettage problem involves different yield criteria, the Bauschinger effect, and the recalculation of the residual stress field post barrel’s machining. Accurate stress-strain data and their appropriate numerical representations are needed as input for the numerical analysis of the residual stress field due to autofrettage. The purpose of the present work is to develop a three-dimensional (3D) numerical solution for both the hydraulic and the swage autofrettage processes incorporating the Bauschinger effect, using an accurate numerical representation of the experimentally measured material behavior. The new 3D computer code that was developed is capable of determining the stresses, strains, displacements, and forces throughout the entire autofrettage process. The numerical results were validated by an instrumented standard swage autofrettage process. The numerical model was found to excellently reproduce the experimentally measured pushing force as well as the permanent bore enlargement of the barrel. The calculated tangential stresses and the measured ones follow a similar pattern, but their numerical magnitude differs considerably. A wide discrepancy in both pattern and magnitude was found between the calculated and the measured axial stresses. These discrepancies seem to stem from the exact details of the mandrel’s insertion into the tube and are now under further investigation. However, in order to further validate the numerical code an hydraulic autofrettage experiment will be performed, which will hopefully eliminate the swage autofrettage discrepancies.

3-D Stress Intensity Factors due to Autofrettage for an Inner Radial Lunular or Crescentic Crack in a Spherical Pressure Vessel

2015 ◽  
Author(s):  
M. Perl ◽  
M. Steiner ◽  
J. Perry
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Field ◽  
Pressure Vessel ◽  
Bauschinger Effect ◽  
Three Dimensional ◽  
Residual Stress Field ◽  
Spherical Pressure

Three dimensional Mode I Stress Intensity Factor (SIF) distributions along the front of an inner radial lunular or crescentic crack emanating from the bore of an autofrettaged spherical pressure vessel are evaluated. The 3-D analysis is performed using the finite element (FE) method employing singular elements along the crack front. A novel realistic autofrettage residual stress field incorporating the Bauschinger effect is applied to the vessel. The residual stress field is simulated in the FE analysis using an equivalent temperature field. SIFs for three vessel geometries (R0/Ri=1.1, 1.2, and 1.7), a wide range of crack depth to wall thickness ratios (a/t=0.01–0.8), various ellipticities (a/c=0.2–1.5), and three levels of autofrettage (e=50%, 75%, and 100%) are evaluated. In total, about two hundred and seventy different crack configurations are analyzed. A detailed study of the influence of the above parameters on the prevailing SIF is conducted. The results clearly indicate the possible favorable effect of autofrettage in considerably reducing the prevailing effective stress intensity factor i.e., delaying crack initiation, slowing crack growth rate, and thus, substantially prolonging the total fatigue life of the vessel. Furthermore, the results emphasize the importance of properly accounting for the Bauschinger effect including re-yielding, as well as the significance of the three dimensional analysis herein performed.

Analysis of Thermal Stresses and Residual Stress Changes in Railroad Wheels Caused by Severe Drag Braking

1977 ◽  
Vol 99 (1) ◽  
pp. 18-23 ◽  
Author(s):  
M. R. Johnson ◽  
R. E. Welch ◽  
K. S. Yeung
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Yield Point ◽  
Thermal Stresses ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Residual Stress Field ◽  
Thermal Stress Field ◽  
Stress Changes ◽  
Railroad Wheels

A finite-element computer program, which takes into consideration nonlinear material behavior after the yield point has been exceeded, has been used to analyze the thermal stresses in railroad freight car wheels subjected to severe drag brake heating. The analysis has been used with typical wheel material properties and wheel configurations to determine the thermal stress field and the extent of regions in the wheel where the yield point is exceeded. The resulting changes in the residual stress field after the wheel has cooled to ambient temperature have also been calculated. It is shown that severe drag braking can lead to the development of residual circumferential tensile stresses in the rim and radial compressive stresses in the plate near both the hub and rim fillets.

Stress Corrosion Cracking Analysis under Thermal Residual Stress Field Using S-FEM

2011 ◽  
Vol 462-463 ◽  
pp. 431-436 ◽  
Author(s):  
Masanori Kikuchi ◽  
Yoshitaka Wada ◽  
Yuto Shimizu ◽  
Yu Long Li
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Crack Growth ◽  
Fracture Behavior ◽  
Three Dimensional ◽  
Stress Fields ◽  
Crack Growth Behavior ◽  
Residual Stress Field ◽  
Energy Agency ◽  
Thermal Stress Field

Fracture in heat affected zone (HAZ) in welding has been a serious problem for the integrity of machines. Prediction of fracture behavior due to the residual stress field in HAZ is important. In this paper, S-Version FEM(S-FEM) is applied to simulate the crack growth under thermal and residual stress fields. For evaluation of stress intensity factor, virtual crack closure integral method (VCCM) is employed. In order to confirm the validity of this analysis, numerical results are compared with previously-reported analytical and experimental results. Then, crack growth analysis in piping structure with welding joint was conducted. The residual stress data was provided by JAEA, Japan Atomic Energy Agency, based on their numerical simulation. Using S-FEM, two- and three-dimensional analyses are conducted, and crack growth behavior under thermal stress field is studied and discussed.

A Comparison of 2D and 3D Fracture Assessments in the Presence of Residual Stresses

2007 ◽  
Author(s):  
Simon J. Lewis ◽  
Christopher E. Truman ◽  
David J. Smith
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Structural Integrity ◽  
Three Dimensional ◽  
External Loading ◽  
Assessment Procedure ◽  
J Integral ◽  
Residual Stress Field ◽  
Fracture Parameters ◽  
Three Dimensional Simulations

This paper presents an investigation into the effects of an initial residual stress field on fracture parameters, calculated via an energy-type integral method, in two and three-dimensional simulations. A residual stress field was introduced into a modified single edge notched bend, SEN(B), specimen using an in-plane compression procedure, such that a crack introduced into the specimen experienced opening displacement, even in the absence of external loading. J integral calculation was undertaken using standard two-dimensional area formulations and pointwise three-dimensional formulations, as well as using modified two- and three-dimensional routines developed to provide path independence in the presence of initial strain fields and non-monotonic plastic loading. The paper will describe the application of these modified J-integral techniques and use the results to re-interpret experimental fracture test data obtained from a set of A533B ferritic steel SEN(B) specimens. The implications for structural integrity assessments in the presence of residual stress fields, as well as the calculation route chosen for determination of fracture parameters, were explored in the context of the R6 assessment procedure. In particular, the different levels of conservatism in the assessments resulting from two- and three-dimensional simulations will be highlighted.

A 3-D Model for Evaluating the Residual Stress Field Due to Swage Autofrettage

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
J. Perry ◽  
M. Perl
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Three Dimensional ◽  
Weight Ratio ◽  
Computer Code ◽  
Residual Stress Field ◽  
Three Dimensional Model ◽  
Equilibrium Equations ◽  
Von Mises ◽  
Experimental Findings

In order to maximize the performance of modern gun barrels in terms of strength-to-weight ratio and total fatigue life, favorable compressive residual stresses are introduced to the inner portion of the barrel, commonly by the autofrettage process. There are two major autofrettage processes for overstraining the tube: the hydrostatic and the swage. There are several theoretical solutions for hydrostatic autofrettage based on Lamé’s solution and the von Mises or Tresca yield criteria. The residual stress field due to hydraulic autofrettage is treated as an axisymmetric two-dimensional problem solved in terms of the radial displacement solely. Once the Bauschinger effect was included in these models they yield very realistic results. Unlike in the case of hydraulic autofrettage, swage autofrettage needs to be modeled by a three-dimensional model. The present analysis suggests a new 3-D axisymmetric model for solving the residual stress field due to swage autofrettage in terms of both the radial and the axial displacements. The axisymmetric equilibrium equations are approximated by finite differences and solved then by Gauss–Seidel method. Using the new computer code the stresses, the strains, the displacements, and the forces are determined. A full-scale instrumented swage autofrettage test was conducted and the numerical results were validated against the experimental findings. The calculated strains, the permanent bore enlargement, and the mandrel pushing force were found to be in very good agreement with the measured values.

Impact of Intensity of Residual Stress Field Upon Re-Yielding and Re-Autofrettage of an Autofrettaged Thick Cylinder

2010 ◽  
Author(s):  
Anthony P. Parker ◽  
John H. Underwood ◽  
Edward Troiano
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Hoop Stress ◽  
Bauschinger Effect ◽  
Numerical Study ◽  
Fatigue Cracks ◽  
Maximum Pressure ◽  
Residual Stress Field ◽  
Intensity Effect ◽  
Elastic Plastic

Re-autofrettage has been identified as a significant, cost-effective method to achieve higher re-yield pressure (RYP) and/or weight reduction in large caliber gun tubes. For a given overstrain, residual stress profiles for hydraulic and for swage autofrettage may differ significantly in their intensity. The simplest representation of this ‘intensity’ effect is the magnitude of the bending moment ‘locked in’ via the residual hoop stress. Hill’s analytical, plane strain, Von Mises, analysis predicts a larger ‘locked-in’ moment than does the equivalent open-end condition. By assuming a range of stress-field intensities (f) scaleing from 1.0 to 1.4 times that produced by open-end hydraulic autofrettage, it was possible to assess re-yield behavior following initial autofrettage via a generic numerical study. In cases where Bauschinger effect is absent, re-yield initiates at the original elastic plastic interface. This includes the ideal Hill distribution. When Bauschinger effect is present, re-yield for f ≤ 1.1 initiates at the bore and after further pressurization at the original elastic plastic interface within two zones. For f ≥ 1.2 the reverse is the case, with initial yield at the original elastic plastic interface and subsequently at the bore. RYP increases with increasing f up to f = 1.175 and then decreases significantly. This loss of RYP may be mitigated by hydraulic re-autofrettage. At f = 1.0 re-autofrettage increases RYP by 4%. At f = 1.4 RYP is increased by 19%. There are modest increases in safe maximum pressure as a result of re-autofrettage. RYP closely approaching re-autofrettage pressure is achievable for f ≥ 1.3. Within this range, re-autofrettage offers a significant benefit. Re-autofrettage also produces beneficial effects via increased bore hoop compressive stress, this increase varying from 20% for f = 1 to zero for f = 1.4. Such increased compression will benefit fatigue lifetime for fatigue cracks initiating at the bore. Conversely, tensile OD hoop stress increases, with increasing f, by a maximum of 6%.

A 3-D Model for Evaluating the Residual Stress Field Due to Swage Autofrettage

2006 ◽  
Author(s):  
J. Perry ◽  
M. Perl
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Three Dimensional ◽  
Weight Ratio ◽  
Computer Code ◽  
Residual Stress Field ◽  
Three Dimensional Model ◽  
Equilibrium Equations ◽  
Von Mises ◽  
Experimental Findings

In order to maximize the performance of modern gun barrels in terms of strength-to-weight ratio and total fatigue life, favorable compressive residual stresses are introduced to the inner portion of the barrel, commonly by the autofrettage process. There are two major autofrettage processes for overstraining the tube: the hydrostatic, and the swage. There are several theoretical solutions for hydrostatic autofrettage, based on Lame´’s solution and the von Mises or Tresca yield criteria. The residual stress field due to hydraulic autofrettage is treated as an axisymetric, two-dimensional problem solved in terms of the radial displacement solely. Once the Bauschinger effect was included in these models they yield very realistic results. Unlike in the case of hydraulic autofrettage, swage autofrettage needs to be modeled by a three-dimensional model. The present analysis suggests a new 3-D axisymmetric model for solving the residual stress field due to swage autofrettage in terms of both the radial and the axial displacements. The axisymetric equilibrium equations are approximated by finite differences and solved then by Gauss-Seidel method. Using the new computer code the stresses, the strains, the displacements and the forces are determined. A full-scale instrumented swage autofrettage test was conducted and the numerical results were validated against the experimental findings. The calculated strains, the permanent bore enlargement, and the mandrel pushing force were found to be in very good agreement with the measured values.

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