Use of A True Material Constitutive Model for Stress Analysis of A Swage Autofrettaged Tube Including Asme Code Comparison

2021 ◽  
Author(s):  
Zhong Hu ◽  
Anthony P Parker
Keyword(s):  
Residual Stress ◽  
Constitutive Model ◽  
Stress Analysis ◽  
Bauschinger Effect ◽  
Kinematic Hardening ◽  
Pressure Vessels ◽  
Material Behavior ◽  
Elastoplastic Material ◽  
Material Constitutive Model ◽  
Deformation Mechanics

Abstract This work reports a new finite element analysis (FEA)-based user programmable function (UPF) featuring true material constitutive behavior with proper algorithms for accurate stress analysis of swage autofrettage of high-strength thick-walled cylinders. The material constitutive model replicates an existing Bauschinger-effect characterization (BEC). This incorporates elastoplastic material behavior during loading. Reversed loading includes a reduced elastic modulus and nonlinear plasticity resulting from the Bauschinger effect (BE), both depend upon the maximum level of loading plastic strain. Swage autofrettage case studies identify the difference in stress distributions based on different material models: a bilinear isotropic material model, a bilinear kinematic hardening model, and the user defined model that features the BEC. Development and integration of such a UPF into a standard FEA package is a crucial unresolved and fundamental modeling issue relating to re-yield, fatigue and fracture of modern swaged cylinders and pressure vessels. It will not only provide a fundamental understanding of the deformation mechanics of the tube during the swage autofrettage process and ensure optimal process parameters are achieved, but also provide guidance for material selection, design and optimization of the manufacturing processes for high intensity cylindrical parts, a potential multibillion-dollar market. Near-bore residual stresses for the BEC case are noteworthy and reported in detail, e.g., axial residual stress is tensile and hoop residual stress exhibits a distinct slope reversal, unlike hydraulic autofrettage, indicating the possible need to re-assess the ASME Pressure Vessel Code (correction for BE) regarding swage autofrettage.

Autofrettaged Cylindrical Vessels and Bauschinger Effect: An Analytical Frame for Evaluating Residual Stress Distributions

2001 ◽  
Vol 124 (1) ◽  
pp. 38-46 ◽  
Author(s):  
Paolo Livieri ◽  
Paolo Lazzarin
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Explicit Form ◽  
Analytical Solutions ◽  
Bauschinger Effect ◽  
Superposition Principle ◽  
Pressure Vessels ◽  
Material Behavior ◽  
Stress Distributions ◽  
Hardening Law

The paper reports analytical solutions valid for residual stresses in cylindrical pressure vessels subjected to autofrettage. The material behavior is thought of as obeying a generic monotonic σ−ε curve and exhibiting the Bauschinger effect during the unloading phase. Under linear and power-hardening conditions, the solution is given in an explicit form. The circumstances under which it is possible to apply the superposition principle also in the presence of localized plasticity are clearly identified. When possible, the final stresses can be obtained by using in an appropriate manner the stress expressions related to the loading phase. Finally, the influence on residual stresses, both of the hardening law and of the shape of the unloading σ−ε curve, is discussed.

Bauschinger Effect Design Procedures for Autofrettaged Tubes Including Material Removal and Sachs’ Method

1999 ◽  
Vol 121 (4) ◽  
pp. 430-437 ◽  
Author(s):  
A. P. Parker ◽  
J. H. Underwood ◽  
D. P. Kendall
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Material Removal ◽  
Bauschinger Effect ◽  
Numerical Procedure ◽  
Pressure Vessels ◽  
Material Behavior ◽  
Stress Fields ◽  
Complete Analysis ◽  
Elastic Plastic

Autofrettage is used to introduce advantageous residual stresses into pressure vessels and to enhance their fatigue lifetimes. The Bauschinger effect serves to reduce the yield strength in compression as a result of prior tensile plastic overload and can produce lower compressive residual hoop stresses near the bore than are predicted by “ideal” autofrettage solutions (elastic/perfectly plastic without Bauschinger effect). A complete analysis procedure is presented which encompasses representation of elastic-plastic uniaxial loading material behavior and of reverse-loading material behavior as a function of plastic strain during loading. Such data are then combined with some yield criterion to accurately predict elastic-plastic residual stress fields within an autofrettaged thick cylinder. Pressure for subsequent reyielding of the tube is calculated. The numerical procedure is further used to determine residual stress fields after removal of material from inside diameter (i.d.) and/or outside diameter (o.d.), including the effects of any further plasticity. A specific material removal sequence is recommended. It is shown that Sachs’ experimental method, which involves removing material from the i.d., may very significantly overestimate autofrettage residual stresses near the bore. Stress ranges and stress intensity factors for cracks within such stress fields are calculated together with the associated fatigue lifetimes as such cracks propagate under cyclic pressurization. The loss of fatigue lifetime resulting from the Bauschinger effect is shown to be extremely significant.

scholarly journals A Comprehensive Numerical Approach for Analyzing the Residual Stresses in AISI 301LN Stainless Steel Induced by Shot Peening

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3338 ◽  
Author(s):  
Fan Zhou ◽  
Wenchun Jiang ◽  
Yang Du ◽  
Chengran Xiao
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Constitutive Model ◽  
Residual Stresses ◽  
Numerical Method ◽  
Shot Peening ◽  
Kinematic Hardening ◽  
Numerical Approach ◽  
Material Behavior ◽  
Single Shot

Shot peening is one of the most famous mechanical surface treatments to improve fatigue performance of metallic components, which is attributed to high amplitude compressive residual stresses. A numerical approach is developed to analyze the residual stresses in 301LN metastable austenitic stainless steel by shot peening. The material behavior is described by a proposed constitutive model in which strain-induced martensitic transformation, isotropic hardening and kinematic hardening effects are taken into account properly. Both single shot and random multiple shots peening were simulated and analyzed. A numerical method is presented with the Python programming language to make the multiple shots follow a random probability distribution. Results demonstrate that the simulated equivalent plastic strains and martensitic volume fractions agree well with the experimental ones, which verify the validity of the constitutive model. Besides, the numerical method is effective at achieving a realistic surface coverage. The maximum compressive residual stress by the Johnson–Cook model is 12% higher than that of the proposed model. Additionally, each hardening effect has an effect on the simulated residual stress. The developed numerical approach can provide a feasible simulation of the shot-peening process and makes an accurate prediction of the residual stress field in 301LN steel.

Consideration of damage in the analysis of autofrettage of thick-walled pressure vessels

2016 ◽  
Vol 230 (20) ◽  
pp. 3585-3593 ◽  
Author(s):  
H Altenbach ◽  
GI Lvov ◽  
K Naumenko ◽  
V Okorokov
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Bauschinger Effect ◽  
Pressure Vessels ◽  
Stress Fields ◽  
Constant Thickness ◽  
Process Conditions ◽  
Material Damage ◽  
Damage Processes ◽  
Walled Cylinder

In this study, the influence of material damage and the Bauschinger effect on the autofrettage of thick-walled pressure vessels is investigated. Constitutive equations for the elasto-plastic deformation and damage processes are presented. Boundary value problems for a thick-walled cylinder and for a thick-walled sphere of constant thickness are formulated. Computations are preformed to find the optimum autofrettage pressure, for which the equivalent stresses in the vessel take the minimum value under process conditions. Furthermore, residual stress fields after the autofrettage are analyzed. The results show that the Bauschinger effect and damage lead to essential reduction of favorable residual stresses.

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.

R6 Weld Modelling Guidelines: Application to Groove Weld Worked Example

2010 ◽  
Author(s):  
R. J. Dennis ◽  
N. A. Leggatt ◽  
M. C. Smith ◽  
P. J. Bouchard
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stress Analysis ◽  
Pressure Vessels ◽  
Integrity Assessment ◽  
Worked Example ◽  
Weld Residual Stress ◽  
Residual Stress Analysis ◽  
Welding Processes

Weld modelling guidelines have recently been developed as part of a new section of the R6 integrity assessment procedure, which is used in the UK nuclear power industry. The intention is to improve the consistency of weld modelling procedures, the accuracy of predicted residual stress profiles and confidence in their use for defect tolerance assessments. The first issue of these guidelines is applicable to austenitic stainless steel joints produced using arc welding processes. The components of interest are mainly thick section nuclear pressure vessels and pipe welds where distortion is not the key issue. Recommendations made in the guidelines are largely based on residual stress analysis methods, validated by measurements on a range of weld mock-ups, developed over several years in support of British Energy projects. The guidelines themselves are divided into two main parts. The procedure itself defines the weld residual stress analysis steps and identifies the key modelling decisions to be made. A much larger section then follows, providing advisory notes on how to make key modelling decisions, with reference to supporting documents and three appendices. The purpose of this paper is to describe the application of the guidelines to a typical weld residual stress assessment. This is in the form of a worked example which details the step-by-step application of the guidelines and describes the key modelling decisions that were made at each step of the procedure. The worked example is for a three bead groove weld specimen. This specimen is an austenitic stainless steel plate with a groove running along the entire length of the plate. The groove is filled with three stringer weld beads.

3D Finite Element Modeling of the Swage Autofrettage Process Including the Bauschinger Effect

2007 ◽  
Author(s):  
E. Troiano ◽  
J. H. Underwood ◽  
R. R. de Swardt ◽  
A. M. Venter ◽  
A. P. Parker ◽  
...  
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Pressure Vessel ◽  
Bauschinger Effect ◽  
Three Dimensional ◽  
Element Model ◽  
Pressure Vessels ◽  
Reverse Loading ◽  
Inherent Nature ◽  
Materials Used

The autofrettage process is a method that produces tensile plastic deformation during the overloading of a pressure vessel which reverses and becomes compressive during unloading. This process produces favorable compressive residual hoop stresses at the bore of the pressure vessel, and results in an increase in the life of the component. In thick walled pressure vessels this process can be accomplished with either a hydraulic or mechanical overloading process. These processes produce different residual stress fields by their inherent nature. The Bauschinger effect, which is observed in most of the materials used in thick walled pressure vessels, is a phenomenon which results in lower reverse loading stresses than those predicted with the classic techniques of Hill and others. The phenomenon is a strong function of the amount of plastic strain during the initial loading of the pressure vessel and results in losses of reverse loading strength of up to 40% in A723 and HB7 steels. A quasi-static three dimensional axi-symmetric finite element model of the swage mandrel autofrettage process of a thick walled pressure vessel is presented in this work. It includes the results of several methodologies for predicting the reduced reverse loading stresses resulting from the Bauschinger effect. The FE results are then shown to compare favorably with neutron diffraction residual stress measurements and yield pressure tests.

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