Service-simulation tests to determine the fatigue life of outside-diameter-notched thick-wall cylinders

1982 ◽  
Vol 22 (3) ◽  
pp. 96-100 ◽  
Author(s):  
J. A. Kapp ◽  
J. H. Underwood
Keyword(s):  
Fatigue Life ◽  
Thick Wall ◽  
Outside Diameter

Fatigue Analysis of Clad and Unclad Thick-Wall Structures

1982 ◽  
Vol 22 (01) ◽  
pp. 151-156
Author(s):  
Theodore Gottlieb ◽  
Tarlochan Mann
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
High Stress ◽  
Cyclic Strain ◽  
Inconel 625 ◽  
Thick Wall ◽  
Low Alloy Steels ◽  
Aisi 316L ◽  
Clad Steel

Abstract It is common practice to clad steel components with a relatively thin layer of a stainless material to prevent corrosion economically. Little, however, has been published regarding the effect of such cladding on fatigue published regarding the effect of such cladding on fatigue life in areas of localized high stress. Large valves that are pressure-cycled often and offshore equipment, such as pressure-cycled often and offshore equipment, such as risers, tensioners, and wellhead flanges that are loaded cyclically by ocean currents and waves, must be analyzed for fatigue life during design. Unlike storage vessels, drilling and completion hardware generally has areas of relatively high stress concentrations because of abrupt section size changes, threads, grooves for seals, bolt holes, and other stress-concentrating geometries. While yielding or rupturing is a function of bulk stresses, fatigue life is a function of peak stresses, which typically are highest on the surface of an area of stress concentration. It has been determined that both the metallurgical characteristics of the cladding and the pressure/load history can be varied to enhance or diminish significantly the fatigue life of a clad steel component. The results and conclusions of this study are based on laboratory studies. Axial fatigue tests (R=0.05) were performed using a side-notched fatigue specimen that produces combined axial and bending stresses in the notched area. Specimens of AISI 4130 (dt HRc 20) were tested unclad and with the notched area clad with Inconel 625 or AISI 316L. Each set of specimens was tested both unpreloaded and preloaded to produce localized yielding at the notched surface only.The findings of this study are applicable to components subject to failure by fatigue and corrosion fatigue and sour service steel components that become locally work-hardened either in service or during overload proof testing as required by most API specifications. Introduction Fatigue failure of a homogeneous, unflawed metal occurs in two stages:nucleation of a stable crack andcrack growth until failure occurs. The nucleation portion is the result of alternating strain of a magnitude portion is the result of alternating strain of a magnitude sufficient to cause the formation and the coalescence of dislocations to form a crack. Crack growth can be predicted by fracture mechanics techniques. predicted by fracture mechanics techniques. Although fatigue curves often are plotted with alternating stress on the abscissa and cycles to failure on the ordinate, it is actually the cyclic strain that determines fatigue life. Fatigue prediction methods therefore must relate calculated stresses to cyclic strain. Stress vs. strain relationships are complex and include at least the following variables: part geometry, grain size, microconstituents, cold working coefficient, direction of forces, magnitude of forces, and strength and modulus of the material. It is seen that fatigue is associated strongly with the metallurgy of the materials being tested. Purpose of Study Purpose of Study The purpose of this study was to develop data and evaluate an analytical technique to predict fatigue life of thick-wall, clad and unclad, pressure vessels in the long- and short-cycle fatigue mode. More specifically, data were generated to simulate high-pressure wellhead equipment fabricated from quenched and tempered low alloy steels. Claddings studied were the austenitic-nickel-base Inconel 625 and iron-base AISI 316L. Both these cladding materials have substantially different metallurgical properties from those of low alloy steel. Since fatigue failures generally result from peak surface stresses, nucleation of fatigue cracks will occur in the cladding. The cladding therefore controls the fatigue life of the vessel since crack nucleation comprises the majority of the total cycles compared to crack growth. SPEJ P. 151

The Study of SCF about Cross Shaped Board - Welded Hollow Spherical Joints

2012 ◽  
Vol 446-449 ◽  
pp. 3108-3114
Author(s):  
Jin Feng Jiao ◽  
Hong Gang Lei
Keyword(s):  
Stress Distribution ◽  
Large Diameter ◽  
Hollow Spheres ◽  
Influence Factors ◽  
Small Diameter ◽  
Thick Wall ◽  
The Cross ◽  
Outside Diameter ◽  
Main Influence

In this paper, the main influence factors of stress-concentrated coefficient Kt of cross shaped board-welded hollow spherical joints were analyzed by ANSYS. Through the combination of 17 specifications of welded hollow spheres and 40 specifications of cross shaped boards to form 122 kinds of cross shaped board–welded hollow spherical Joints, the paper mainly analyzed the influence on stress-concentrated coefficient Kt from some factors as follows: the length of the connection of the cross shaped boards (a)、the thickness of the cross shaped boards (t) , the outside diameter of the welded-hollow spheres (D) , the thickness of the spheres (δ), the weld size (hf) and the cross shaped boards which are cut or not. The analysis results showed: the SCF of the joints and some factors（a、t、D、δand hf） in all .A cross shaped board to cut its corner or not affected the stress distribution of the joints and the biggest difference between 12%; In the cross shaped boards connected the same length, when it rises to some degree, the influence of (δ) on ( Kt) is smaller; Along with the thickness of the large diameter welded hollow spheres increases, the slope of the stress-concentrated coefficient Kt increases; It is better to choose the hollow spheres with the small diameter or thick wall, and choose the cross shaped boards which shall be a little thinner, and also increase the connected length between the welded hollow spheres and the cross shaped boards; When the weld size is larger than or equal to 12 millimeters, SCF gently changes.

Fatigue Life of Commercial High Pressure Tubing

2002 ◽  
Author(s):  
Michael D. Mann
Keyword(s):  
High Pressure ◽  
Fatigue Life ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Thick Wall ◽  
Pressure Tubing ◽  
Safety And Reliability ◽  
Section Viii ◽  
Critical Components ◽  
Axial Fatigue

Design guidance for high pressure components, has undergone a dramatic change with the release of ASME Section VIII division 3 pressure vessel code. For the first time, a thorough design criteria is available for design of thick wall pressure vessels. The most critical components of a design are safety and reliability. Ultra high-pressure vessels, in most cases, do not have an “infinite” life. The design must therefore be “leak before break” and a design cycle life must be specified. This paper looks at the effects of fatigue on commercial high-pressure tubing under tri-axial fatigue. The tubing investigated is 316 stainless steel 9/16″ and 3/8″ diameter 4100 bar (60,000 psi) tubing. The testing was performed using a tri-axial fatigue machine originally designed by Dr. B. Crossland, Dr. J. L. M. Morrison and Dr. J. S. C. Perry in 1960 and upgraded by the Author. This investigation compares the fatigue life prediction per KD3 in the ASME pressure vessel code Section VIII division 3 and actual test results from the fatigue machine. This verification gives important reliability data for commercial hardware used in high-pressure piping.

Development of a New Thermo-Mechanical Environmental Fatigue Testing Facility to Investigate the Impact of Thermal Strain Gradients on Fatigue Initiation

2016 ◽  
Author(s):  
N. Platts ◽  
P. Brown ◽  
P. J. Gill ◽  
R. D. Smith ◽  
J. W. Stairmand
Keyword(s):  
Fatigue Life ◽  
Thermal Shock ◽  
Shock Loading ◽  
Thermal Strain ◽  
Thick Wall ◽  
Thin Wall ◽  
Strain Gradients ◽  
Thermal Transients ◽  
Wide Range ◽  
The Impact

Light water reactor coolant environments are known to significantly reduce the fatigue life of austenitic stainless steels. However, most available data are derived from isothermal testing of membrane loaded tensile specimens, whereas the majority of plant loading transients result from thermal transients and involve significant through-wall strain gradients. This paper describes the development of a high temperature water facility to enable both thin and thick wall hollow fatigue endurance specimens to be subjected to thermal and mechanical loading for a wide range of thermal cycles including rapid shock loading. Thermal shock loading from 300°C to between 40 and 150°C has been achieved and Finite Element Analysis, FEA, has been used to calculate the thermally induced strain profiles through a 12mm thick-wall specimen. This indicates peak surface thermal strain ranges of up to 0.8% for a transient between 300 and 40°C. Testing is underway to investigate the impact of the strain gradient and thermal waveform on the fatigue life of this specimen where significantly longer lives may be expected compared to membrane loaded specimens. The ability within the same facility to apply simulated thermal shock profiles to both thick-wall specimens and mechanically loaded thin wall specimens provides a powerful tool to assess the impact of thermal fatigue loading and thermal strain gradients on component life.

scholarly journals Mitigation for Hawser‘s Short Fatigue Life on The Study of The Fatigue Life Prediction of Hawser in Single Point Mooring (SPM) at Tuban Fuel Terminal

2019 ◽  
Vol 63 (3) ◽  
pp. 5-12
Author(s):  
Ahmad Syafiul Mujahid ◽  
Keyword(s):  
Numerical Simulation ◽  
Fatigue Life ◽  
Life Prediction ◽  
Single Point ◽  
Time History ◽  
Fatigue Life Prediction ◽  
Fuel Oil ◽  
Mooring Lines ◽  
Tension Time ◽  
Outside Diameter

One of the vital components of SPM System is Mooring Hawser. Mooring Hawser is mooring lines that used to anchor the tanker ship that are berthed at Single Point Mooring (SPM) fuel terminal to loading or offloading the fuel oil. The incident of broken hawser unexpectedly due to short fatigue life that occurs on hawser when tanker ship that is anchored at SPM 150.000 DWT at Tuban Seas, East Java, Indonesia is the basis of this study for mitigation and replace of new hawser. This study calculates fatigue life of the hawser by using numerical simulation approach and Palmgren-Miner Methods. the hawser variation that conducted is only at the size of the outside diameter, namely: 0.144 m, 0.152 m, and 0.160 m. The material properties of the hawser in this study are Nylon Polyamide PA66. Numerical simulation consist of two steps: Hydrodynamics diffraction numerical simulation is used to obtain response (RAO) of tanker ship and SPM, and hydrodynamics time response numerical simulation is used to obtain effective hawser tension time history in 3600 second time simulation. By using the S-N Curve of Nylon Polyamide PA66 that is obtained from Jernej Klemenc, Andrej Wagner, and Matija Fadjiga (2011) as the basis to calculate fatigue life prediction of three variations in the outside diameter of the hawserwith Palmgren-Miner methods. The calculation result of new hawser fatigue life = 57.40536 Months or 4.718249 Years of Effective Berthing Time. The new hawser use outside diameter variation = 0.152 m to replace the previous hawser.

Mechanics Design Models for Advanced Pressure Vessels: Autofrettage With Higher Strength Steel; Steel Liner - Composite Jacket Configurations; Alternative Thermal Barrier Coatings

2010 ◽  
Author(s):  
John H. Underwood ◽  
Robert H. Carter ◽  
Edward Troiano ◽  
Anthony P. Parker
Keyword(s):  
Fatigue Life ◽  
Thermal Barrier Coatings ◽  
Thermal Stresses ◽  
Steel Substrate ◽  
Pressure Vessels ◽  
Thick Wall ◽  
Thermal Barrier ◽  
Equivalent Weight ◽  
Barrier Coatings ◽  
Steel Liner

Solid mechanics models are described of mechanical and thermal stresses in 1000–1400 MPa yield strength, autofrettaged, steel pressure vessels. Modeling results describe idealized advanced vessel configurations with improved resistance to mechanical damage from internal pressure and thermal damage from transient internal heating. [i] Calculations of autofrettage hoop residual stresses are based on the classic Hill elastic-plastic results for thick-wall tubes, with modifications to account for the Bauschinger-reduced compressive strength of the tube steel near the bore. [ii] Stresses in metal liner - composite jacket tubes are calculated using the Parker layered-tube model, which gives applied and residual elastic stresses for two-layer tubes with specified properties and interference between layers. [iii] Transient thermal stresses in bore barrier coatings are calculated using the finite difference methods of Witherell, describing one-dimensional, convection-conduction heat flow, focusing on near-bore temperatures using time-dependent combustion gas temperatures and convection coefficient data from interior ballistic codes. Temperatures are obtained for various thicknesses of metallic and ceramic coatings on steel substrate, using temperature-dependent conductivity and diffusivity data for the coatings and substrate. In-situ verification of calculated temperature profiles is done by comparing with metallographic observation of depths of the steel phase transformation and the known characteristic transformation temperature. When the transient shear stress near the interface exceeds the reduced elevated-temperature strength of the interface, coating segments are modeled to be lost by shear failure, which in turn would lead to rapid hot-gas erosion of the steel substrate. Results of the model calculations are used to identify potential improvements in advanced pressure vessels, using idealized configurations as examples. [i] Autofrettage of higher strength steel vessels shows significant increase in both yield pressure and fatigue life, but poorer resistance to both hydrogen cracking and yield-before-break final failure, compared to traditional lower strength designs of equivalent weight. [ii] Vessels with steel liner and either high strength carbon/epoxy or unidirectional Al2O3/Al jacket and high liner-jacket interference show similar fatigue life to that of all-steel designs of equivalent weight. However radial compressive crushing of composite materials in transverse orientation limits composite jacketed vessels to lower applied pressure than all-steel designs. [iii] Metal thermal barrier coatings generally suffer from compressive yielding at elevated temperatures near the bore, leading to tensile residual stress, cracking, and erosion failure. The higher hot strength of a Si3N4 ceramic provides significant improvement in yielding and cracking resistance and thus erosion resistance, compared with metal coatings subjected to the same thermal conditions.

Analysis of ASME Codes for Fatigue of Pressure Vessels

2010 ◽  
Author(s):  
Khalil Farhangdoost ◽  
Payman Hamrahan
Keyword(s):  
Finite Element Method ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Maximum Stress ◽  
Pressure Vessels ◽  
Thick Wall ◽  
Abaqus Software ◽  
Element Method

In industries, pressure vessels or in general thick-wall cylinders under internal pressure are important parts and analysis of their applications in various conditions is essential. Therefore, for design of pressure vessels usage of standard codes like ASME is necessary. Most of cracked or damaged pressure vessels are exposed to cyclic loading. This failure process is fatigue. ASME codes have some codes for analyzing this process. These codes show the conditions and formulas for fatigue analysis. In this paper, a thick wall pressure vessel is analyzed with three cyclic loading regimes. The maximum stress intensity, fatigue life and damage factor are calculated by ASME codes. Then by usage of finite element method, ASME results are compared for fatigue life analysis. Previous investigations show that nozzle connection area of pressure vessels have high stress concentration, and usually crack is propagated from this zone. Thus fatigue analysis is accomplished for nozzle connection of pressure vessel by ASME codes and finite element method. Then nine shape of crack with same crack front size are modeled on the maximum stress zone of the nozzle connection. Then stresses of crack fronts and stress intensity factors of cracks are computed by finite element method with ABAQUS software which is powerful for fracture mechanic analysis. The critical crack which is elliptical prismatic crack virtually is grown step by step and for each step, stress intensity factor is computed by ABAQUS software. With relation between stress intensity factor and crack size also using Paris formula, fatigue life is computed. This operation is done for two type of crack growth. In first type length and depth of crack are grown and in second type only crack length is grown. Finally, the fatigue life obtained from Paris formula and ASME codes are compared.

Development of a Fatigue Life Assessment and Prediction Framework for a Bimetallic-Welded Thick-Wall Component of a Steam Turbine

2016 ◽  
Author(s):  
M.-H. Herman Shen ◽  
Sajedur Akanda ◽  
Xia Liu ◽  
Peng Wang
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Steam Turbine ◽  
Room Temperature ◽  
Analytical Framework ◽  
Fatigue Tests ◽  
Life Assessment ◽  
Thick Wall ◽  
Fatigue Life Assessment ◽  
Control Constant

In this investigation, we have applied an integrated experimental-analytical framework for fatigue life assessment and prediction of a thick-wall component of a high-pressure (HP) steam turbine. Emphasis is placed on the development of an effective experimental and analytical procedure for life characterization on the basis of low cycle and high cycle fatigue (LCF/HCF) in order to improve the safety, reliability, and affordability of real world steam turbine operations. Stress-control constant amplitude fully reversed fatigue tests were performed in room temperature and 500°C to serve two purposes: (a) to obtain experimental stress-life (S-N) curves and (b) to assess the values of the parameters of the energy-based framework to predict the fatigue life. The experimental and the predicted S-N curves are compared with each other in case of both the room and the elevated temperature to examine the soundness of the present energy-based model to predict fatigue life. The present lifing model was found to be able to predict both the room and elevated temperature LCF/HCF life of the thick-wall component with excellent accuracy. Furthermore, the elevated temperature fatigue life is found to be lower than the room temperature fatigue life due to the lower fatigue toughness at elevated temperature.

Fatigue Life Analyses and Tests for Thick-Wall Cylinders Including Effects of Overstrain and Axial Grooves

1995 ◽  
Vol 117 (3) ◽  
pp. 222-226 ◽  
Author(s):  
J. H. Underwood ◽  
A. P. Parker
Keyword(s):  
Fatigue Life ◽  
Crack Growth ◽  
Good Description ◽  
Crack Size ◽  
Initial Crack ◽  
Thick Wall ◽  
Inner Diameter ◽  
Life Analysis ◽  
Fatigue Life Analysis ◽  
Laboratory Life

A fracture mechanics-based fatigue life analysis was developed for overstrained, pressurized thick-wall cylinders with one or several semi-elliptical-shaped axial grooves at the inner diameter. The fatigue life for a crack initiating at the root of the groove was calculated for various cylinder, groove, and crack configurations and for different material yielding conditions. Comparisons were made with fatigue crack growth and laboratory life results from A723 thick-wall cylinders, in which cannon firing tests were first performed to produce axial erosion grooves, followed by cyclic hydraulic pressurization to failure in the laboratory. The life analysis, with an initial crack size based on the expected preexisting defects, gave a good description of the crack growth and fatigue life of the tests for cylinders with and without grooves. General fatigue life calculations summarized important material and configurational effects on the fatigue life design of overstrained cylinders, including effects of material yield strength, cylinder diameter ratio, stress concentration factor, and initial crack size.

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