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%.

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

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Anthony P. Parker ◽  
Edward Troiano ◽  
John H. Underwood
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 reyield pressure (RYP) and/or weight reduction in large caliber gun tubes. For a given overstrain, residual stress profiles for hydraulic and 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) scaling from 1.0 to 1.4 times that were produced by open-end hydraulic autofrettage, it was possible to assess reyield behavior following initial autofrettage via a generic numerical study. In cases where Bauschinger effect is absent, reyield initiates at the original elastic–plastic interface. This includes the ideal Hill distribution. When Bauschinger effect is present, reyield 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 (SMP) 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 0% for f = 1.4. Such increased compression will benefit fatigue lifetime for fatigue cracks initiating at the bore. Conversely, tensile outside diameter (OD) hoop stress increases, with increasing f, by a maximum of 6%.

A Numerical Study on the Redistribution of Residual Stress After Machining

2017 ◽  
Author(s):  
Kunyang Lin ◽  
Wenhu Wang ◽  
Ruisong Jiang ◽  
Yifeng Xiong
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Numerical Study ◽  
Cutting Speed ◽  
Machining Process ◽  
Stress Profile ◽  
Residual Stress Field ◽  
Machining Processes ◽  
Residual Stress Profile

Machining induced residual stresses have an important effect on the surface integrity. Effects of various factors on the distribution of residual stress profiles induced by different machining processes have been investigated by many researchers. However, the initial residual, as one of the important factor that affect the residual stress profile, is always been ignored. In this paper, the residual stress field induced by the quenching process is simulated by the FEM software as the initial condition. Then the initial residual stress field is used to study the residual stress redistribution after the machining process. The influence of initial stress on the stress formation is carried out illustrating with the mechanical and thermal loads during machining processes. The effects of cutting speed on the distribution of residual stress profile are also discussed. These results are helpful to understand how initial residual stresses are redistributed during machining better. Furthermore, the results in the numerical study can be used to explain the machining distortion problem caused by residual stress in the further work.

Residual Stress Regenerated on Low Plasticity Burnished Inconel 718 Surface After Initial Turning Process

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Yang Hua ◽  
Zhanqiang Liu ◽  
Bing Wang ◽  
Jiaming Jiang
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Analytical Model ◽  
Inconel 718 ◽  
Plastic Behavior ◽  
Residual Stress Field ◽  
Workpiece Material ◽  
Elastic Plastic ◽  
Initial Residual Stress ◽  
Low Plasticity Burnishing

Abstract Low plasticity burnishing (LPB) has been extensively employed in aero-industry to enhance fatigue performance of machined components by introducing compressive residual stress. Effects of various parameters on the residual stress field induced by low plasticity burnishing have been investigated by many researchers. However, initial residual stresses induced by machining are one of the important factors which affect the residual stress regenerated by the LPB process. The present work aims to develop an analytical model which takes into account the initial residual stress and burnishing parameters to predict residual stress field of workpiece material Inconel 718 based on Hertz contact theory and elastic–plastic theory. Initial residual stress fields were produced by turning of Inconel 718 and were measured by using X-ray diffraction technique. Two types of material constitutive models such as the linear hardening model and isotropic–kinematic model were employed to describe the elastic–plastic behavior of workpiece material Inconel 718. An analytical study was performed to analyze the effect of the initial residual stress field and burnishing parameters on residual stress induced by low plastic burnishing. The results of analytical model were verified by conducting the LPB experiments on initial turned Inconel 718. The results showed that the shape and magnitude of the residual stress field obtained with considering the effect of initial residual stress field was in good accordance with experimental measurements.

The Effect of Strength Mis-Match and Residual Stress in ECA of Girth Welds With Internal Circumferential Cracks

2009 ◽  
Author(s):  
Ali Mirzaee Sisan ◽  
Afshin Motarjemi
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Driving Forces ◽  
Numerical Study ◽  
Welding Process ◽  
Detailed Comparison ◽  
Weld Strength ◽  
Residual Stress Field ◽  
Girth Welds ◽  
Welded Pipe

A numerical study was carried out to quantify the effect of a residual stress field on subsequent fracture behaviour of a girth welded pipe with an internal circumferential long crack when subjected to high applied strain loading. In order to introduce an initial residual stress field similar to a welding process in a pipe, a quenching process was numerically simulated and associated residual stress profiles were modified and mapped into the finite element (FE) models. A detailed comparison between the crack driving force for various cases with and without residual stress and weld strength mismatch was carried out for cases under a high plastic deformation regime. The BS7910 procedure was also used to predict crack driving forces using its current assumption of interaction of residual stress with primary loads. The results obtained from the FE analyses were compared with the BS7910 predictions.

Measurement of Residual Hoop Stresses in Cylinders Using the Compliance Method

1986 ◽  
Vol 108 (2) ◽  
pp. 87-92 ◽  
Author(s):  
Weili Cheng ◽  
Iain Finnie
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Hoop Stress ◽  
Axial Stress ◽  
Hole Drilling ◽  
Residual Stress Field ◽  
Axial Coordinate ◽  
X Ray ◽  
Axial Crack ◽  
Hoop Stresses

A method is proposed for measurement of the hoop stress in an axisymmetric residual stress field in cylinders in which the axial stress is independent of the axial coordinate. The method involves measuring strains at the outside surface while an axial crack is cut progressively from the outside. Experimental results are presented for two short cylindrical rings cut from a long quenched cylinder. Good general agreement is obtained with X-ray and hole drilling measurements of residual stresses.

Effect of Residual Stress Field in Front of the Slant Precrack Tip on Bent Fatigue Crack Propagation

2007 ◽  
Vol 353-358 ◽  
pp. 1207-1210 ◽  
Author(s):  
Kenichi Shimizu ◽  
Tashiyuki Torii ◽  
J. Nyuya ◽  
Y. Ma
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Stress Field ◽  
Mixed Mode ◽  
Compressive Residual Stress ◽  
Fatigue Cracks ◽  
Crack Opening ◽  
Residual Stress Field ◽  
Method Analysis ◽  
Crack Sliding Displacement

Fatigue crack bending and propagation behaviors were studied under mixed-mode conditions using annealed and fatigue slant precracks. The bent fatigue crack initiated from the fatigue slant precrack propagated under mixed-mode conditions with mode II stress intensity factor evaluated from the crack sliding displacement measured along the crack. On the other hand, bent fatigue cracks propagated under the mode I condition for an annealed slant precrack specimen. The forces which suppress the crack opening/sliding were calculated along the slant precrack and the bent crack by FEM (Finite Element Method) analysis. As a result, the crack opening suppress forces were generated by the compressive residual stress around the fatigue slant precrack, while the forces which promote the crack sliding were caused by the residual stress field in front of the fatigue slant precrack.

An evaluation of residual stress distribution in welded compact tension specimens using neutron diffraction

2005 ◽  
Vol 40 (2) ◽  
pp. 211-216 ◽  
Author(s):  
G. O Rading
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Neutron Diffraction ◽  
Stress Field ◽  
Fatigue Cracks ◽  
Compact Tension ◽  
Maximum Tensile Stress ◽  
Thickness Variation ◽  
Residual Stress Field ◽  
Neutron Diffraction Technique

The neutron diffraction technique was used to determine the residual stress field in welded compact tension specimens of the aluminium-lithium alloy AA 2095. The deep penetrating characteristic of neutrons was exploited to evaluate the through-thickness variation in residual stress. Moreover, insight into the redistribution of these stresses was gained by extending a fatigue crack through the residual stress field and re-examining the stress distribution. The specimen without a crack was found to have a high compressive stress (of the order of - 135MPa) ahead of the notch. This rose to a maximum tensile stress of about 50MPa, 22 mm from the notch, followed by a drop to negative values further ahead of the notch. It was observed that the magnitude of the stresses changed on moving into the thickness of the specimen. However, the form of the graph showing stress versus distance ahead of the notch remained unchanged. When fatigue cracks of different lengths were introduced, the magnitude of the stress close to the tip first increased with crack length, before decreasing and then rising again. Nevertheless, the form of the graph remained unchanged and the stress at the crack tip remained compressive. The paper concludes that any study of the response of a component to mechanical loading involving a residual stress field must take these factors (i.e. through-thickness stress variation and stress redistribution) into consideration.

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.

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