UK Research Programme on Residual Stresses: Progress to Date

2007 ◽  
Author(s):  
S. K. Bate ◽  
A. P. Warren ◽  
C. T. Watson ◽  
P. Hurrell ◽  
J. A. Francis
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Research Programme ◽  
Assessment Procedure ◽  
Engineering Structures ◽  
Element Analysis ◽  
Simplifying Assumptions ◽  
Modelling Techniques

A long-term UK research programme on residual stresses was launched in 2004. It involves Rolls-Royce plc and Serco Assurance, and is supported by UK industry and academia. The programme is aimed at progressing the understanding of weld residual stresses and the implementation of finite element simulation and residual stress measurement for assessing the integrity of engineering structures. Following on from this, the intention is then to develop improved guidance on residual stress modelling techniques. In the first two years finite element activities have addressed heat source representation, simplified modelling (e.g. 2D v 3D, bead lumping), material hardening models, high temperature behaviour and phase transformations. It is recognized that simplifying assumptions have to be made in order to reduce the computational run-time and modelling complexity, especially for multi-pass welds. The effects of these assumptions on the determined stresses have been considered by carrying out finite element analyses of welded mock-ups. The welded mock-ups have been developed to provide measured residual stress data which are necessary to validate the modelling techniques that have been developed. These activities have been used to support the development of guidelines on the use finite element analysis to predict residual stresses in welded components. These guidelines will be incorporated in the next issue of the British Energy R6 defect assessment procedure.

scholarly journals UK Research Programme on Residual Stresses: A Review of Progress

2008 ◽  
Author(s):  
S. K. Bate ◽  
P. Hurrell ◽  
J. A. Francis ◽  
M. Turski
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Experimental Testing ◽  
Research Programme ◽  
Austenitic Steels ◽  
Assessment Procedure ◽  
Engineering Structures ◽  
Modelling Techniques

A long-term UK research programme on residual stresses was launched in 2004. It involves Rolls-Royce plc and Serco Assurance, supported by UK industry and academia. The programme is aimed at progressing the understanding of weld residual stresses and the implementation of finite element simulation and residual stress measurement for assessing the integrity of engineering structures. Following on from this, the intention is then to develop improved guidance on residual stress modelling techniques and then to provide methods and analysis tools for design in order to control and minimise residual stress. The focus of the work to date has been to develop modelling guidelines which can be used by a finite element analyst to predict the residual stresses in austenitic welded components. These guidelines are now drafted and will be incorporated into the next issue of the British Energy R6 defect assessment procedure following peer review. The guidelines have been developed based on the experience that has been attained using various modelling techniques. To support this development, a series of welded mock-ups have been manufactured. The residual stresses in these welds have been measured using various techniques (diffraction and strain relaxation). These measurements are being used to validate the predicted stresses. It is only by corroborating each other that the resulting residual stresses can be confidently used for assessment. Mock-ups are also being used to develop material models for ferritic steel which undergo phase transformations, and to investigate how various weld parameters affect the magnitude and distribution of residual stress. Similarly, mock-ups have been manufactured to investigate the effect of start-stops on residual stresses. The programme is also supported by experimental testing to develop physical and mechanical properties which are required for analysis, i.e. up to melting temperature. Both conventional and miniaturised testing has been used to measure properties in ferritic and austenitic steels. A task has also been undertaken to develop a methodology for providing upper bound residual stress profiles which can be used as an initial estimate of stress for use in structural assessment.

New UK Research Programme on Residual Stresses

2006 ◽  
Author(s):  
Steve K. Bate ◽  
Chris Watson
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Stress Measurement ◽  
Research Work ◽  
Research Programme ◽  
Residual Stress Measurement ◽  
Engineering Structures ◽  
The Uk

A new long-term research programme has been launched in the UK. This involves Rolls-Royce plc and Serco Assurance, supported by UK industry and academia. A significant part of this programme is aimed at progressing the understanding of weld residual stresses and the implementation of finite element simulation and residual stress measurement for assessing the structural integrity of engineering structures and components. The work includes: (1) Finite element modelling to investigate heat source representation, material behaviour and 3D v 2D effects. (2) Design and manufacture of mock-ups for supporting validation. (3) Residual stress measurement. (4) Weld design. (5) Residual stress profiles. (6) Material testing. (7) Development of a procedure for residual stress modelling. The work is being undertaken by a combination of finite element analyses and residual stress measurement using a variety of techniques. This paper presents an overview of the research work being undertaken and provides examples of the outcome of some of the studies obtained to-date.

The Validation of Weld Residual Stresses for Use in Structural Integrity Assessment

2011 ◽  
Vol 70 ◽  
pp. 297-302 ◽  
Author(s):  
Steve K. Bate ◽  
P. John Bouchard
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Measurement Techniques ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Modelling Techniques ◽  
High Level ◽  
Assessment Procedures

The continued safe and reliable operation of plant invariably has to consider the assessment of defects in welded structural components. This requires some estimate of the residual stresses that have developed during the welding fabrication process. For as-welded structures these stresses can be of yield magnitude. Engineering critical assessment procedures such as R6, BS 7910, FITNET and API 579-1 provide simplified estimates, bounding profiles or advice on detailed analysis or measurement which can be applied to provide conservative estimates of the remaining life of plant. The use of finite element analysis (FEA) is being applied more frequently to predict residual stresses in welded components for assessment purposes. This calculation involves complex non-linear analyses with many assumptions. As a consequence, the accuracy and reliability of solutions is variable. In order to improve the consistency of weld modelling, and hence the accuracy and confidence in their use, a set of Guidelines covering the calculation of residual stresses have been developed. The residual stress calculations need to be validated before the results can be used in assessments and guidance on how to demonstrate the required standard of validation proof is provided with these Guidelines. The level of validation required, depends on the problem being solved and the sensitivity of the assessment to the presence of residual stress. For example a high level of validation may be required for assessments of safety critical plant. To support these calculations, measurements are required and a series of ‘Weld Residual Stress Benchmarks’, describing welded mock-ups which have been measured using various measurement techniques, are being collated which the users can then refer to when validating their finite element modelling techniques and thus provide a greater confidence in the predicted results.

Finite Element and Experimental Analysis of Residual Stresses in Electron Beam Welded Nickel-Based Superalloys

2021 ◽  
Author(s):  
Tom Saju ◽  
M. Velu
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Electron Beam ◽  
Residual Stresses ◽  
Electron Beam Welding ◽  
Stress Measurement ◽  
Welding Parameters ◽  
Element Analysis ◽  
Longitudinal Residual Stress ◽  
Nimonic 80A

In this paper, two different nickel-based superalloys, namely Inconel 718 and Nimonic 80A were joined using electron beam welding techniques with three different welding parameters. A finite element analysis (FEA) using Abaqus software was carried out to calculate the residual stresses due to welding. Both transverse and longitudinal residual stresses were determined. Also, an X-ray residual stress measurement system, μ-X360 Ver. 2.5.6.2 was used for measuring transverse residual stress along and across the weld centerline. The transverse residual stress found by FEA and that measured experimentally was nearly the same thus validating the FEA. Also, the peak values of longitudinal residual stress found using the FEA were close to the yield strengths of the base metals as found elsewhere.

Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Yield Strength ◽  
Residual Stresses ◽  
Solid Mechanics ◽  
Element Model ◽  
Pressure Vessels ◽  
Material Strength ◽  
Element Analysis

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.

Fast Three-Dimensional Finite Element Analysis of Weld Overlay Application on a Formed Feeder Elbow

2011 ◽  
Author(s):  
Francis H. Ku ◽  
Pete C. Riccardella
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Residual Stresses ◽  
Nuclear Reactor ◽  
Three Dimensional ◽  
Fe Method ◽  
Element Analysis ◽  
Weld Overlay ◽  
Welding Processes

This paper presents a fast finite element analysis (FEA) model to efficiently predict the residual stresses in a feeder elbow in a CANDU nuclear reactor coolant system throughout the various stages of the manufacturing and welding processes, including elbow forming, Grayloc hub weld, and weld overlay application. The finite element (FE) method employs optimized FEA procedure along with three-dimensional (3-D) elastic-plastic technology and large deformation capability to predict the residual stresses due to the feeder forming and various welding processes. The results demonstrate that the fast FEA method captures the residual stress trends with acceptable accuracy and, hence, provides an efficient and practical tool for performing complicated parametric 3-D weld residual stress studies.

Deep Hole Drill Residual Stress Measurement Technique Experimental Validation

2006 ◽  
Vol 524-525 ◽  
pp. 549-554 ◽  
Author(s):  
W.R. Mabe ◽  
W.J. Koller ◽  
A.M. Holloway ◽  
P.R. Stukenborg
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Test Specimen ◽  
Experimental Validation ◽  
Stress Measurement ◽  
Reference Solution ◽  
Deep Hole ◽  
Element Analysis ◽  
Validation Test

This paper presents the results of an experimental validation of the deep hole drill residual stress measurement method. A validation test specimen was fabricated and plastically loaded to impose a permanent residual stress field within the specimen. The validation test specimen was designed to provide a variety of stress profiles as a function of location within the specimen. A finite element analysis of the validation test specimen was performed in order to provide a reference solution for comparison to the deep hole drill experimental results. Results from experimental testing of the validation test specimen agree well with the finite element analysis reference solution, thereby providing further validation of the deep hole drill method to measure residual stresses.

Estimation of Residual Stresses in Steel Welded Joints Using Three Dimensional Finite Element Analysis

2018 ◽  
Author(s):  
Shivdayal Patel ◽  
B. P. Patel ◽  
Suhail Ahmad
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Residual Stresses ◽  
Boundary Conditions ◽  
Welding Speed ◽  
Welded Joints ◽  
Plate Thickness ◽  
Welding Process ◽  
Element Analysis

Welding is one of the most used joining methods in the ship industry. However, residual stresses are induced in the welded joints due to the rapid heating and cooling leading to inhomogenously distributed dimensional changes and non-uniform plastic and thermal strains. A number of factors, such as welding speed, boundary conditions, weld geometry, weld thickness, welding current/voltage, number of weld passes, pre-/post-heating etc, influence the residual stress distribution. The main aim of this work is to estimate the residual stresses in welded joints through finite element analysis and to investigate the effects of boundary conditions, welding speed and plate thickness on through the thickness/surface distributions of residual stresses. The welding process is simulated using 3D Finite element model in ABAQUS FE software in two steps: 1. Transient thermal analysis and 2. Quasi-static thermo-elasto-plastic analysis. The normal residual stresses along and across the weld in the weld tow region are found to be significant with nonlinear distribution. The residual stresses increase with the increase in the thickness of the plates being welded. The nature of the normal residual stress along the weld is found to be tensile-compressive-tensile and the nature of normal residual stress across the weld is found to be tensile along the thickness direction.

Experimental characterization and finite element modeling of the residual stresses in laser-assisted mechanical micromachining of Inconel 625

2015 ◽  
Vol 231 (10) ◽  
pp. 1735-1751 ◽  
Author(s):  
Avik Samanta ◽  
Mahesh Teli ◽  
Ramesh Singh
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Cutting Forces ◽  
Laser Heating ◽  
Stress Measurement ◽  
Cutting Speed ◽  
Inconel 625 ◽  
Beam Diameter ◽  
Mechanical Micromachining

Laser-assisted mechanical micromachining offers the ability to machine difficult-to-cut materials, like superalloys and ceramics, more efficiently and economically by laser-induced localized thermal softening prior to cutting. Laser-assisted mechanical micromachining is a micromachining process with localized laser heating which could affect the cutting forces and the machined surface integrity. The residual stresses obtained in the laser-assisted mechanical micromachining process depend on both mechanical loading and the laser heating. This article focuses on the experimental process characterization and prediction of the cutting forces and the residual stresses in a laser-assisted mechanical micromachining–based orthogonal machining of Inconel 625. The results show that the laser assistance reduces the mean cutting forces by ∼25% and enhances the normal compressive residual stress at the surface by ∼50%. Since microscale residual stress measurement is very time-intensive, a coupled-field thermo-mechanical finite element model of laser-assisted mechanical micromachining has been developed to predict the temperature, cutting forces and the residual stresses. The cutting forces and residual stresses’ predictions are in good agreement with the measured values during machining. In addition, parametric simulations have been carried out for laser power, cutting speed, cutting edge radius, rake angle, laser location and laser beam diameter to study their effect on cutting forces and surface residual stresses.

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