Thermal Simulation of an Arbitrary Residual Stress Field in a Fully or Partially Autofrettaged Thick-Walled Spherical Pressure Vessel

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
M. Perl
Keyword(s):  
Residual Stress ◽  
Temperature Field ◽  
Stress Field ◽  
Pressure Vessel ◽  
Fe Analysis ◽  
Stress Fields ◽  
Equivalent Temperature ◽  
Residual Stress Field ◽  
Spherical Pressure ◽  
The Ideal

The equivalent thermal load was previously shown to be the only feasible method by which the residual stresses due to autofrettage and its redistribution, as a result of cracking, can be implemented in a finite element (FE) analysis of a fully or partially autofrettaged thick-walled cylindrical pressure vessel. The present analysis involves developing a similar methodology for treating an autofrettaged thick-walled spherical pressure vessel. A general procedure for evaluating the equivalent temperature loading for simulating an arbitrary, analytical or numerical spherosymmetric autofrettage residual stress field in a spherical pressure vessel is developed. Once presented, the algorithm is applied to two distinct cases. In the first case, an analytical expression for the equivalent thermal loading is obtained for the ideal autofrettage stress field in a spherical shell. In the second case, the algorithm is applied to the discrete numerical values of a realistic autofrettage residual stress field incorporating the Bauschinger effect. As a result, a discrete equivalent temperature field is obtained. Furthermore, a FE analysis is performed for each of the above cases, applying the respective temperature field to the spherical vessel. The induced stress fields are evaluated for each case and then compared to the original stress. The FE results prove that the proposed procedure yields equivalent temperature fields that in turn simulate very accurately the residual stress fields for both the ideal and the realistic autofrettage cases.

Thermal Simulation of an Arbitrary Residual Stress Field in a Fully or Partially Autofrettaged Thick-Walled Spherical Pressure Vessel

2008 ◽  
Author(s):  
M. Perl
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Field ◽  
Pressure Vessel ◽  
Stress Fields ◽  
Equivalent Temperature ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Spherical Pressure ◽  
The Ideal

The equivalent thermal load was previously shown to be the only feasible method by which the residual stresses due to autofrettage and its redistribution, as a result of cracking, can be implemented in a finite element analysis, of a fully or partially autofrettaged thick-walled cylindrical pressure vessel. The present analysis involves developing a similar methodology for treating an autofrettaged thick-walled spherical pressure vessel. A general procedure for evaluating the equivalent temperature loading for simulating an arbitrary, analytical or numerical, spherosymmetric autofrettage residual stress field in a spherical pressure vessel is developed. Once presented, the algorithm is applied to two distinct cases. In the first case, an analytical expression for the equivalent thermal loading is obtained for the ideal autofrettage stress field in a spherical shell. In the second case, the algorithm is applied to the discrete numerical values of a realistic autofrettage residual stress field incorporating the Bauschinger effect. As a result, a discrete equivalent temperature field is obtained. Furthermore, a finite element analysis is performed for each of the above cases, applying the respective temperature field to the spherical vessel. The induced stress fields are evaluated for each case and then compared to the original stress. The finite element results prove that the proposed procedure yields equivalent temperature fields that in turn simulate very accurately the residual stress fields for both the ideal and the realistic autofrettage cases.

A Numerical Model for Evaluating the Residual Stress Field in an Autofrettaged Spherical Pressure Vessel Incorporating the Bauschinger Effect

2007 ◽  
Author(s):  
M. Perl ◽  
J. Perry
Keyword(s):  
Differential Equation ◽  
Residual Stress ◽  
Stress Field ◽  
Pressure Vessel ◽  
Weight Ratio ◽  
Pressure Vessels ◽  
Flow Rule ◽  
Plastic Strains ◽  
Residual Stress Field ◽  
Spherical Pressure

Increased strength-to-weight ratio and extended fatigue life are the main objectives in the optimal design of modern pressure vessels. These two goals can mutually be achieved by creating a proper residual stress field in the vessel’s wall, by a process known as autofrettage. Although there are many studies that have investigated the autofrettage problem for cylindrical vessels, only few such studies exist for spherical ones. There are two principal autofrettage processes for pressure vessels: hydrostatic and swage autofrettage, but spherical vessels can only undergo the hydrostatic one. Because of the spherosymmetry of the problem, autofrettage in a spherical pressure vessel is treated as a two-dimensional problem and solved solely in terms of the radial displacement. The mathematical model is based on the idea of solving the elasto-plastic autofrettage problem using the form of the elastic solution. Substituting Hooke’s equations into the equilibrium equation and using the strain-displacement relations, yields a differential equation, which is a function of the plastic strains. The plastic strains are determined using the Prandtl-Reuss flow rule and the differential equation is solved by the explicit finite difference method. The previously developed 2-D computer program, for the evaluation of hydrostatic autofrettage in a thick-walled cylinder, is adapted to handle the problem of spherical autofrettage. The appropriate residual stresses are then evaluated using the new code. The presently obtained residual stress field is then compared to three existing solutions emphasizing the major role the material law plays in determining the autofrettage residual stress field.

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.

Temperature and Residual Stress Fields in an Austenitic Circumferential Pipe Weld

2002 ◽  
Author(s):  
Ruthard Bonn ◽  
Klaus Metzner ◽  
H. Kockelmann ◽  
E. Roos ◽  
L. Stumpfrock
Keyword(s):  
Residual Stress ◽  
Numerical Calculation ◽  
Stress Field ◽  
Quantitative Determination ◽  
Welding Residual Stress ◽  
Stress Fields ◽  
Residual Stress Field ◽  
Circumferential Welds ◽  
The Impact

The main target of a research programme “experimental and numerical analyses on the residual stress field in the area of circumferential welds in austenitic pipe welds”, sponsored by Technische Vereinigung der Großkraftwerksbetreiber e. V. (VGB) and carried out at MPA Stuttgart, was the validation of the numerical calculation for the quantitative determination of residual stress fields in austenitic circumferential pipe welds. In addition, the influence of operational stresses as well as the impact of the pressure test on the residual stress state had to be examined. By using the TIG orbital welding technique, circumferential welds (Material X 10 CrNiNb 18 9 (1.4550, corresponding to TP 347) were produced (geometric dimensions 255.4 mm I.D. × 8.8 mm wall) with welding boundary conditions and weld parameters (number of weld layers and weld built-up, seam volume, heat input) which are representative for pipings in power plants. Deformation and temperature measurements accompanying the welding, as well as the experimentally determined (X-ray diffraction) welding residual stress distribution, served as the basis for the verification of numeric temperature and residual stress field calculations. The material model on which the calculations were founded was developed by experimental weld simulations in the thermo-mechanical test rig GLEEBLE 2000 for the determination of the material behaviour at different temperatures and elasto-plastic deformation. The numeric calculations were carried out with the Finite Element program ABAQUS. The comparison of the calculation results with the experimental findings confirms the proven validation of the developed numerical calculation models for the quantitative determination of residual stresses in austenitic circumferential pipings. The investigation gives a well-founded insight into the complex thermo-mechanical processes during welding, not known to this extent from literature previously.

Key Technology Research of the Temperature Field Simulation Based on the Flat Butt Weld

2012 ◽  
Vol 562-564 ◽  
pp. 729-732 ◽  
Author(s):  
Yu Wen Li ◽  
Fu Xing Wang
Keyword(s):  
Residual Stress ◽  
Temperature Field ◽  
Stress Field ◽  
Field Distribution ◽  
Welding Process ◽  
Residual Stress Field ◽  
Butt Weld ◽  
Temperature Method ◽  
Simulation Based ◽  
Direct Loading

Aluminum as solder, in the flat welding process, the temperature field and the residual stress field distribution was the main problem of the study; According to the actual situation of the welding process, using the direct loading temperature method and the indirect loading temperature method , the main path of temperature field distribution curves and the residual stress field distribution were gained by 2D numerical simulation respectively; Through comparison, the indirect loading method can get more accuracy of residual stress field distribution than that of the direct loading temperature method; The above methods were useful in practical production.

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.

Finite Element Analysis of Temperature Filed and Stress Field of Reducer

2014 ◽  
Vol 881-883 ◽  
pp. 1447-1450
Author(s):  
Jing Zhang ◽  
Fei Wang
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Field ◽  
Stress Field ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Welding Temperature ◽  
Stress And Deformation ◽  
Residual Stress And Deformation

Abstract.The connection mode of reducer with straight tube on both sides are the welding connection. There are two weld at the both side of reducer and there has a great influence on residual stress and deformation in the process of welding . Based on the particularity of reducer welding, the paper is focus on the residual stress and deformation in the process of welding, using large-scale finite element analysis software ANSYS .The DN500X450 reducer model is established.The welding temperature field and residual stress field is analysis and calculation and analysis the influence on temperature and stress distribution of reducer. The results show that the maximum of the temperature and the residual stress is located in the big side and reduce the welding seam, and the obvious deformation also find in the big side and reduce joint . The reducing pipe’s distribution of temperature field and residual stress field are obtained,providing the basis to establish properly and optimize of welding process.

scholarly journals Numerical Reconstruction of Residual Stress Fields from Limited Measurements

2014 ◽  
Vol 996 ◽  
pp. 243-248
Author(s):  
Harry E. Coules ◽  
David J. Smith ◽  
Karim H.A. Serasli
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Measurement Data ◽  
Stress Fields ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Numerical Reconstruction ◽  
Incomplete Measurement ◽  
Stress States ◽  
Measurement Strategies

By finding stress states which are consistent both with any existing experimental measurements and with elasticity theory, residual stress fields can often be reconstructed from incomplete measurement data. We discuss such methods of residual stress reconstruction, their implementation using finite element analysis, and the measurement strategies which enable them. In general, reconstruction of residual stress fields must be formulated as an inverse problem, which can usually be solved using stress basis functions. However, prior knowledge of the form of the residual stress field and/or underlying eigenstrain distribution often allows the problem to be reduced such that inverse methods become unnecessary, greatly simplifying the analysis. Two examples of when residual stress field reconstruction can be simplified in this way are given.

A Validated Numerical Model for Residual Stress Predictions in an Eight-Pass-Welded Stainless Steel Plate

2014 ◽  
Vol 777 ◽  
pp. 46-51 ◽  
Author(s):  
Vipulkumar I. Patel ◽  
Ondrej Muránsky ◽  
Cory J. Hamelin ◽  
Mitch D. Olson ◽  
Michael R. Hill ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Stress Field ◽  
Steel Plate ◽  
Fe Analysis ◽  
Contour Method ◽  
Stainless Steel Plate ◽  
Residual Stress Field ◽  
Longitudinal Residual Stress ◽  
Welding Processes

Welding processes create a complex transient state of temperature that results in post-weld residual stresses. The current work presents a finite element (FE) analysis of the residual stress distribution in an eight-pass slot weld, conducted using a 316L austenitic stainless steel plate with 308L stainless steel filler metal. A thermal FE model is used to calibrate the transient thermal profile applied during the welding process. Time-resolved body heat flux data from this model is then used in a mechanical FE analysis to predict the resultant post-weld residual stress field. The mechanical analysis made use of the Lemaitre-Chaboche mixed isotropic-kinematic work-hardening model to accurately capture the constitutive response of the 316L weldment during the simulated multi-pass weld process, which results in an applied cyclic thermo-mechanical loading. The analysis is validated by contour method measurements performed on a representative weld specimen. Reasonable agreement between the predicted longitudinal residual stress field and contour measurement is observed, giving confidence in the results of measurements and FE weld model presented.

The Beneficial Contribution of Realistic Autofrettage to the Load-Carrying Capacity of Thick-Walled Spherical Pressure Vessels

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
M. Perl ◽  
J. Perry
Keyword(s):  
Differential Equation ◽  
Residual Stress ◽  
Stress Field ◽  
Weight Ratio ◽  
Pressure Vessels ◽  
Flow Rule ◽  
Plastic Strains ◽  
Residual Stress Field ◽  
Explicit Finite Difference ◽  
Spherical Pressure

Increased strength-to-weight ratio and extended fatigue life are the main objectives in the optimal design of modern pressure vessels. These two goals can mutually be achieved by creating a proper residual stress field in the vessel’s wall by a process known as autofrettage. Although there are many studies that have investigated the autofrettage problem for cylindrical vessels, only a few of such studies exist for spherical ones. Because of the spherosymmetry of the problem, autofrettage in a spherical pressure vessel is treated as a one-dimensional problem and solved solely in terms of the radial displacement. The mathematical model is based on the idea of solving the elastoplastic autofrettage problem using the form of the elastic solution. Substituting Hooke’s equations into the equilibrium equation and using the strain-displacement relations yield a differential equation, which is a function of the plastic strains. The plastic strains are determined using the Prandtl–Reuss flow rule and the differential equation is solved by the explicit finite difference method. The existing 2D computer program, for the evaluation of hydrostatic autofrettage in a thick-walled cylinder, is adapted to handle the problem of spherical autofrettage. The presently obtained residual stress field is then validated against three existing solutions emphasizing the major role the material law plays in determining the autofrettage residual stress field. The new code is applied to a series of spherical pressure vessels yielding two major conclusions. First, the process of autofrettage increases considerably the maximum safe pressure that can be applied to the vessel. This beneficial effect can also be used to reduce the vessel’s weight rather than to increase the allowable internal pressure. Second, the specific maximum safe pressure increases as the vessel becomes thinner. The present results clearly indicate that autofrettaging of spherical pressure vessels can be very advantageous in various applications.

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