Residual Stresses and Lifetimes of Tubes Subjected to Shrink Fit Prior to Autofrettage

2003 ◽  
Vol 125 (3) ◽  
pp. 282-286 ◽  
Author(s):  
Anthony P. Parker ◽  
David P. Kendall
Keyword(s):  
Material Removal ◽  
Hoop Stress ◽  
Bauschinger Effect ◽  
External Pressure ◽  
Fatigue Lifetime ◽  
Shrink Fitting ◽  
Plain Tube ◽  
Specific Geometry ◽  
Shrink Fit ◽  
Summary Data

There is increasing interest in the use of compound cylinders that combine shrink fit and autofrettage, taking account of Bauschinger effect. Previous work has analyzed material removal from a plain, autofrettaged cylinder and the application of an external pressure or shrink to a previously autofrettaged plain tube. In this paper a different design philosophy is examined, namely the shrink fitting of two tubes prior to autofrettage. Such a process is shown to be beneficial in inhibiting loss of near-bore compressive residual hoop stress due to Bauschinger effect and thereby increasing calculated fatigue lifetime. These effects are described in detail for a specific geometry, and summary data suitable for use by designers are presented for a large range of configurations.

Bauschinger Effect Design Procedures for Compound Tubes Containing an Autofrettaged Layer

2000 ◽  
Vol 123 (2) ◽  
pp. 203-206 ◽  
Author(s):  
Anthony P. Parker
Keyword(s):  
Bauschinger Effect ◽  
Design Procedure ◽  
External Pressure ◽  
Pressure Vessels ◽  
Design Procedures ◽  
Shrink Fitting ◽  
Stress Profiles ◽  
Hoop Stresses ◽  
Shrink Fit ◽  
Outside Diameter

Autofrettage is used to introduce advantageous residual stresses into pressure vessels. The Bauschinger effect can produce less compressive residual hoop stresses near the bore than are predicted by “ideal” autofrettage solutions. A design procedure was recently proposed which models material removal from the bore or outside diameter of a single, plain autofrettaged tube in the presence of Bauschinger effect. This paper extends the procedure to model the addition of pressure or of material (via shrink-fit) to the tube, providing associated residual stress profiles following various amounts of further yielding due to a net external pressure. Simple criteria are developed for determining, and avoiding, further yielding in the autofrettaged tube when it is used as part of a compound assembly involving shrink-fitting; these criteria are based upon net pressure differential between the bore and outside diameter of the autofrettaged tube. An alternative criterion, based upon bore hoop stress, is shown to be erroneous.

A Re-Autofrettage Procedure for Mitigation of Bauschinger Effect in Thick Cylinders

2004 ◽  
Vol 126 (4) ◽  
pp. 451-454 ◽  
Author(s):  
Anthony P. Parker
Keyword(s):  
Yield Strength ◽  
Residual Stresses ◽  
Fracture Resistance ◽  
Hoop Stress ◽  
Bauschinger Effect ◽  
Pressure Vessels ◽  
Fatigue Lifetime ◽  
Cyclic Pressure ◽  
Manufacturing Procedure ◽  
Tube Geometry

A manufacturing procedure for enhancing residual stresses and thereby improving fatigue lifetime and fracture resistance of pressure vessels is proposed. The procedure involves initial autofrettage; one or more “heat soak plus autofrettage” sequences and an optional final heat soak. Stresses are calculated numerically for traditional, single autofrettage and compared with those created by the new procedure. The loss of bore compressive hoop stress due to Bauschinger effect is predicted to be significantly reduced. Associated fatigue lifetime calculations indicate that life may be improved by a factor of between 2 and 30, depending upon tube geometry and the ratio of cyclic pressure to yield strength. Repeated overload plus heat soak cycles may also be of benefit in other engineering design scenarios.

A Re-Autofrettage Procedure for Mitigation of Bauschinger Effect in Thick Cylinders

2005 ◽  
Author(s):  
Anthony P. Parker
Keyword(s):  
Yield Strength ◽  
Residual Stresses ◽  
Fracture Resistance ◽  
Hoop Stress ◽  
Bauschinger Effect ◽  
Pressure Vessels ◽  
Fatigue Lifetime ◽  
Cyclic Pressure ◽  
Manufacturing Procedure ◽  
Tube Geometry

A manufacturing procedure for enhancing residual stresses and thereby improving fatigue lifetime and fracture resistance of pressure vessels is proposed. The procedure involves initial autofrettage; one or more ‘heat soak plus autofrettage’ sequences and an optional final heat soak. Stresses are calculated numerically for traditional, single autofrettage and compared with those created by the new procedure. The loss of bore compressive hoop stress due to Bauschinger effect is predicted to be significantly reduced. Associated fatigue lifetime calculations indicate that life may be improved by a factor of between 2 and 30, depending upon tube geometry and the ratio of cyclic pressure to yield strength. Repeated overload plus heat soak cycles may also be of benefit in other engineering design scenarios.

Bauschinger Effect’ Influence on the Componud Cylinder Containing an Autofrettaged Layer

2007 ◽  
Vol 345-346 ◽  
pp. 149-152 ◽  
Author(s):  
Young Shin Lee ◽  
Jae Hyun Park ◽  
Jae Hoon Kim ◽  
Ki Up Cha ◽  
Suk Kyun Hong
Keyword(s):  
Finite Element Method ◽  
Residual Stress ◽  
Finite Element ◽  
Bauschinger Effect ◽  
External Pressure ◽  
The Finite Element Method ◽  
Compound Cylinder ◽  
Shrink Fitting ◽  
Stress Profiles ◽  
Hoop Stresses

Autofrettage is used to introduce advantageous residual stresses into cylinders. The Bauschinger effect can produce less compressive residual hoop stresses near the bore than are predicted “ideal” autofrettage solutions. A723 steel is used for compound cylinder. This paper extends the analysis to material the addition of pressure or of shrink-fitting to the cylinders, providing associated residual stress profiles following various amounts of further yielding due to a net external pressure. The Bauschinger effects for “realistic” – Bauschinger effect dependent autofrettage are obtained. The 2-D analysis is performed via the finite element method. The Bauschinger effect is found to significantly lower the beneficial stress due to autofrettage.

Hydraulic Versus Swage Autofrettage and Implications of the Bauschinger Effect

2003 ◽  
Vol 125 (3) ◽  
pp. 309-314 ◽  
Author(s):  
A. P. Parker ◽  
G. P. O’Hara ◽  
J. H. Underwood
Keyword(s):  
Residual Stresses ◽  
Experimental Evidence ◽  
Hybrid Method ◽  
Bauschinger Effect ◽  
Pressure Level ◽  
Opening Angle ◽  
Fatigue Lifetime ◽  
Analysis Of Results

A hybrid method is presented which permits calculation of residual stresses in a swage autofrettaged tube including Bauschinger effect. The results are generally supported by three types of available experimental evidence by comparing “equivalent” swage and hydraulic autofrettage tubes having the same level of overstrain. Radial slitting of the swaged tube is predicted to show a greater opening angle than its hydraulic equivalent. Fatigue lifetime of the swaged tube is predicted to be significantly higher than the hydraulic case. Re-pressurization of the equivalent tubes is predicted to produce initial re-yielding at the same pressure in both cases. Analysis of results shows that permanent strains in the swaged tube are expected to appear at a pressure level below that for the hydraulic tube.

AN ANALYTICAL SOLUTION FOR OPTIMUM DESIGN OF SHRINK-FIT MULTI-LAYER COMPOUND CYLINDERS

2012 ◽  
Vol 04 (04) ◽  
pp. 1250043 ◽  
Author(s):  
M. SHARIFI ◽  
J. ARGHAVANI ◽  
M. R. HEMATIYAN
Keyword(s):  
Shear Stress ◽  
Optimum Design ◽  
Maximum Shear Stress ◽  
Layer Compound ◽  
Compound Cylinder ◽  
Number Of Layers ◽  
Shrink Fitting ◽  
Tresca Criterion ◽  
Analytical Relations ◽  
Shrink Fit

In this paper, employing an analytical method, optimum design of multi-layer compound cylinders is investigated. To this end, considering Tresca criterion, maximum shear stress in each layer is minimized. Analytical relations for optimum values of a layer dimension, residual pressures and radial interferences are derived. A technique for shrink-fitting of layers is also proposed and relationships for radial interferences, residual pressures and required temperature differences during the shrink-fitting process are derived. Three different examples are presented to show the effectiveness of the proposed method. It is shown that increasing the number of layers makes shear stress distribution near to uniform. As a result, with specified maximum shear stress and inner radius, the weight of compound cylinder is decreased when the number of layers is increased. Moreover, compound cylinders with more layers have lower maximum shear stress for a specified weight. It is also concluded that if the ratio of outer to inner radii be larger, increasing the number of layers is more effective.

Research of Reinforce Stress on the Pressure Structure of Submersible Vehicle

2014 ◽  
Vol 496-500 ◽  
pp. 590-593
Author(s):  
Guan Nan Chu ◽  
Qing Yong Zhang ◽  
Guo Chun Lu
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Hoop Stress ◽  
External Pressure ◽  
Finite Element Models ◽  
Cylinder Pressure ◽  
Simulation Experiments ◽  
Element Analysis ◽  
Load Carrying

In order to improve the load-carrying properties of pressure structure, a new method to improve the external bearing limit is put forward and residual stress is used. Based on finite element analysis, finite element models of cylinder pressure structure of submersible vehicle are established to produce hoop residual stress in the process of outward expansion. According to a lot of data of simulation experiments, the result indicates that hoop residual stress is compressive on the outer surface of the pipe and the hoop stress keeps tensile on the inside surface. This kind of stress distribution is helpful to the cylinder structure and can improve its bearing capacity of external pressure. Moreover, the rules of the residual stress are got. The influences of physical dimension, yield strength of material and the expansion rate to the stress distribution are analyzed. The measures to produce the stress distribution are also presented.

Heavy Gauge UOE Pipe With Improved Compressive Strength for Offshore Pipeline

2012 ◽  
Author(s):  
Nobuyuki Ishikawa ◽  
Hitoshi Sueyoshi ◽  
Kimihiro Nishimura ◽  
Osamu Yamamoto ◽  
Akihiko Tanizawa ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Bauschinger Effect ◽  
External Pressure ◽  
Accelerated Cooling ◽  
Second Phase ◽  
Fundamental Study ◽  
Soft Phase ◽  
Collapse Pressure ◽  
Bainitic Microstructure ◽  
Line Process

Offshore gas pipeline development has been expanding toward deeper water region that requires pipes to have strong resistance against collapse by external pressure. Collapse pressure is mainly dominated by pipe roundness and compressive strength. In order to improve compressive strength, it is quite important to understand the Bauschinger effect caused by cyclic deformation during pipe forming. Compressive strength is reduced by the Bauschinger effect since compression in the circumferential direction is applied after the pipe expansion. Therefore, prevention of Bauschinger effect is an important issue for improving compressive strength of pipes. In this paper, the effect of microstructure on the Bauschinger effect was investigated. It was proved that microstructure that consists of a hard second phase shows a large strength reduction in reverse loading, since a mixed microstructure with soft phase and hard phase enhances the Bauschinger effect. In order to obtain homogeneous bainitic microstructure, advanced plate production technology, where heat treatment on-line process (HOP) is applied after accelerated cooling, was developed. The steel produced by HOP process exhibits a fine bainitic microstructure with very low amount of hard second phase such as MA constituent. It was demonstrated that the trial produced pipe with HOP process has a higher compressive strength than conventional pipes. In addition to the fundamental study on compressive strength, further investigations were conducted to optimize other material properties for offshore linepipe, such as DWTT property, resistance to hydrogen induced cracking and HAZ toughness to comply with DNV requirements. Production tests of Grade X65 linepipe with the 38mm WT and 876mm OD was carried out. Material and mechanical properties of these heavy gauge linepipes were introduced.

Assembly of Compound Tubes Under Hydraulic Pressure

2006 ◽  
Vol 128 (2) ◽  
pp. 208-211 ◽  
Author(s):  
Tony D. Andrews
Keyword(s):  
Wear Resistance ◽  
Compressive Strength ◽  
Plastic Strain ◽  
Compressive Stress ◽  
Bauschinger Effect ◽  
No Reduction ◽  
Hydraulic Pressure ◽  
Maximum Compressive Stress ◽  
Compressive Stresses ◽  
Shrink Fit

This paper describes a method for inserting a tapered liner into a sleeve while the latter is expanded by hydraulic pressure. The technique avoids many of the limitations associated with traditional shrink fit techniques and autofrettage. The sleeve and liner are manufactured with internal and external tapers, respectively, to give the appropriate interference for the finished compound tube. The liner is mounted on a rod and positioned loosely inside the sleeve. The ends of the sleeve are sealed with plugs, which allow the rod to protrude through each end and which also have hydraulic oil inlets. Once the assembly has been pressurized, the rod is pushed into the vessel to move the liner further into the sleeve generating an interference once the pressure in the sleeve is removed. Insertion of a relatively thin liner can generate high residual compressive stresses at the bore, similar to autofrettage but with a shallower gradient away from the bore. Because the liner is not subjected to plastic strain during manufacture, there is no reduction in compressive strength due to the Bauschinger effect and the maximum compressive stress obtainable is greater than that from traditional autofrettage routes. Such high stresses lead to excess tension in the sleeve, which must be reduced by autofrettaging the sleeve prior to assembly of the compound tube. Such a configuration is suitable for inserting a part-length liner at the chamber for strength and/or wear resistance and tensile stresses can be eliminated to prevent failure of brittle materials, such as ceramics.

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