Crack Extension Effects on Welding Residual Stress in Fitness for Service Assessment of Crack-Like Defect in Weld

2016 ◽  
Author(s):  
Jeong K. Hong
Keyword(s):  
Residual Stress ◽  
3D Models ◽  
Crack Size ◽  
Welding Residual Stress ◽  
Welding Parameters ◽  
Element Analysis ◽  
Defect Assessment ◽  
Technical Issues ◽  
Model Geometry ◽  
2D And 3D

The current industry code and standard fitness-for-service assessment (ICS FFSA) procedures ignore the release of the welding residual stress (WRS) in defect assessment of a crack growing in a WRS field. Doing so can result in overly restrictive results in the ICS FFSA of an engineering component. The current ICS FFSA procedures have produced compendiums of WRS distributions and stress intensity factor (SIF) solutions that are characterized by the joint geometry and welding parameters. It is also known that these distributions are based on extensive numerical analyses and provide upper bound estimates; therefore, these types of solutions do not necessarily satisfy the self-equilibrating state. In this investigation, through-wall WRS distributions from the literature data, including measurements and finite element analysis (FEA) results for girth welded pipes, are compared to the representative ICS FFSA WRS procedures. Also, the WRS and SIF solutions using the proposed procedure are compared to those using the ICS FFSA procedures employing 2D and 3D models. From the investigation, it is observed that the ICS FFSA procedures show discrepancies for certain conditions and the levels of conservatism are dependent on the model geometry, boundary constraint condition, crack size, and crack shape. For some cases, the estimations provided from the ICS FFSA procedures are not conservative compared to the reference solutions from literatures and FEA simulations. As a continuous study of the previous investigation [OMAE 2015-41319], the objective of the present paper is to motivate the industry to improve ICS FFSA procedures by clarifying the ambiguous technical issues of crack-like defect assessment in weld regions.

Influence of Welding Parameters on Residual Stress in 9% Ni Steel for Low Temperature Service

2010 ◽  
Vol 154-155 ◽  
pp. 1618-1623 ◽  
Author(s):  
Chun Yan Yan ◽  
Wu Shen Li ◽  
Shi Wu Bai
Keyword(s):  
Residual Stress ◽  
Temperature Field ◽  
Welded Joint ◽  
Welding Residual Stress ◽  
Welding Parameters ◽  
Transformation Theory ◽  
Element Analysis ◽  
Heat Transfer Theory ◽  
Longitudinal Residual Stress ◽  
Simulation Results

Based on welding heat transfer theory, heat elastoplasticity theory and phase transformation theory, welding residual stress in multi-layer welded joint of 9% Ni steel for liquefied natural gas (LNG) storage tanks was simulated using SYSWELD finite element analysis software. Taking into account nonlinear relationships between temperature and mechanical properties, together with influence of transformation latent heat on temperature field, double ellipsoid heat source model was applied in the simulation of the three fields (temperature field, microstructure field and stress-strain field). Distribution pattern of welding residual stress in 9%Ni steel welded joint was obtained through numerical simulation. Results showed that heat affected zone (HAZ) showing high-level residual stress was the main stress concentrated part of the welded joint. Longitudinal residual stress appeared to be tensile in the weld and HAZ, and compressive in regions remote from the weld. A match of low heat input and high interpass temperature should be employed to lower residual stress level in HAZ. Simulation results were well consistent with theoretical analysis.

Issues in Welding Residual Stress Model in Fitness for Service Assessment of Crack-Like Defect in Weld Area

2015 ◽  
Author(s):  
Jeong K. (J. K.) Hong ◽  
Richard P. Brodzinski ◽  
Pedro M. Vargas ◽  
H. Chong Rhee ◽  
K-John Young ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Growth ◽  
Driving Force ◽  
Welding Residual Stress ◽  
Element Analysis ◽  
Crack Driving Force ◽  
Defect Assessment ◽  
Technical Issues ◽  
Weld Area ◽  
Force Calculation

Current Industry Code and Standard (ICS) Fitness for Service Assessment (FFSA) procedures for crack-like defect in weld area tend to impose high level of conservatism. In addition to the necessity for using conservative Welding Residual Stress (WRS) model due to the uncertainty inherent in the WRS estimation, using the original WRS regardless of crack depth in the crack driving force calculation, like the applied operating load, is the primary reason for this solution conservatism. In addition, current ICS weld area defect assessment procedures involve ambiguities in boundary condition effects on WRS models, as well as in the fracture mode of weld area crack being treated in the context of opening mode only, even though there is no weld area geometric symmetry essential for precluding fracture modes other than mode I. To clarify these technical issues in the ICS FFSA practices rigorous numerical simulation analyses of welding process and crack growth following joint fabrication have been performed, using the finite element analysis procedure. A crack driving force calculation procedure for weld area cracks, which was developed to quantify the crack extension effects on WRS for growing crack, was used for the finite element crack growth simulation analyses. The rigorous finite element analysis results for boundary condition effects on WRS, the fracture mode of weld toe crack, and crack growth effects on crack driving force parameters caused by WRS are compared with those of current ICS solutions. These comparisons demonstrate the need for an improvement of the current ICS FFSA procedures for weld area crack-like defects. The primary objective of the present paper is to motivate the industry to improve ICS FFSA procedures by clarifying these ambiguous technical issues in weld area crack-like defect assessment parameters, as well as considering crack extension effects on WRS properly in calculating the crack driving force of growing crack to reduce undue conservatism in FFSA.

Influence of Laser Shock Processing on the Weld Line and Finite Element Simulation

2011 ◽  
Vol 464 ◽  
pp. 627-631
Author(s):  
Jie Zhang ◽  
Ai Hua Sun ◽  
Le Zhu ◽  
Xiang Gu
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Welding Residual Stress ◽  
Laser Shock ◽  
Analysis Software ◽  
Laser Shock Processing ◽  
Element Analysis ◽  
Welding Line ◽  
Simulation Results ◽  
Shock Processing

Welding residual stress is one of the main factors that affect the strength and life of components. In order to explore the effect on residual stress of welding line by laser shock processing, finite element analysis software ANSYS is used to simulate the welding process, to calculate the distribution of welding residual stress field. On this basis, then AYSYS/LS-DYNA is used to simulate the laser shock processing on welding line. Simulation results show that residual stress distributions of weld region, heat-affected region and matrix by laser shock processing are clearly improved, and the tensile stress of weld region effectively reduce or eliminate. The simulation results and experimental results are generally consistent, it offer reasons for parameter optimization of welding and laser shock processing by finite element analysis software.

Effect of Welding Residual Stress on the Buckling Behavior of Storage Tanks Subjected to Harmonic Settlement

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Jian-Guo Gong ◽  
Lei Yu ◽  
Feng Wang ◽  
Fu-Zhen Xuan
Keyword(s):  
Residual Stress ◽  
Design Method ◽  
Welding Residual Stress ◽  
Welding Parameters ◽  
Strengthening Effect ◽  
Storage Tanks ◽  
Buckling Strength ◽  
Welding Joint ◽  
Buckling Behavior ◽  
Significant Difference

The effect of welding residual stress on the buckling behavior of storage tanks subjected to the harmonic settlement was simulated using the shell-to-solid coupling method. In the numerical model of tanks coupled with the welding residual stress, the welding joint and its adjacent zone were modeled using the solid submodel and the zone far away from the welding joint was built by the shell submodel. Effects of welding parameters (e.g., welding velocities and welding passes) on the buckling behavior of tanks were analyzed systematically. Results indicate that the buckling strength of tanks is enhanced due to the welding residual stress. Comparatively, a slow welding velocity presents a more remarkable strengthening effect than the fast welding velocity due to a larger axial residual stress produced at the welding joint. Nevertheless, no significant difference between the double-side welding and the one-side welding for buckling strength enhancement is observed for the cases studied. This indicates that the current design method causes a conservative design without considering the welding residual stress.

Research on the Effects of Welding Sequence on Welding Residual Stress of High-Speed Train Based on SYSWELD

2011 ◽  
Vol 399-401 ◽  
pp. 1806-1811
Author(s):  
Yong Hong Chen ◽  
Peng Chen ◽  
Ai Qin Tian
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
High Speed ◽  
Element Model ◽  
Welding Residual Stress ◽  
High Speed Train ◽  
Distribution Law ◽  
Element Analysis ◽  
Welding Sequence ◽  
Maximum Residual Stress

The finite element model of the roof of aluminum high-speed train was established, double ellipsoid heat source was employed, and heat elastic-plastic theory was used to simulate welding residual stress of the component under different welding sequence based on the finite element analysis software SYSWELD. The distribution law of welding residual stress was obtained. And the effects of the welding sequence on the value and distribution of residual stress was analyzed. The numerical results showed that the simulation data agree well with experimental test data. The maximum residual stress appears in the weld seam and nearby. The residual stress value decreases far away from the welding center. Welding sequence has a significant impact on the final welding residual stress when welding the roof of aluminum body. The side whose residual stress needs to be controlled should be welded first.

scholarly journals Study on Residual Stress of Welded Hoop Structure

2020 ◽  
Vol 10 (8) ◽  
pp. 2838
Author(s):  
Wenbo Ma ◽  
Heng Zhang ◽  
Wei Zhu ◽  
Fu Xu ◽  
Caiqian Yang
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Welding Speed ◽  
Weld Seam ◽  
Outer Cylinder ◽  
Three Dimensional ◽  
Welding Residual Stress ◽  
Welding Parameters ◽  
Forming Process ◽  
Maximum Residual Stress

Residual stress is inevitable during welding, which will greatly affect the reliability of the structure. The purpose of this paper was to study the residual stress of the hoop structure caused by the cooling shrinkage of the weld when the outer cylinder was wrapped and welded under the condition of the existing inner cylinder. In this paper, the “method of killing activating elements” of ANSYS was used to simulate the three-dimensional finite element of the hoop structure. In the case of applying interlayer friction, the welding-forming process and welding circumferential residual stress of the hoop structure were analyzed. The blind hole method was used to test the residual stress distribution of the hoop structure, and the test results were compared with the finite element simulation results to verify the reliability of the simulation calculation method and the reliability of the calculation results. Then, the influence factors of the maximum welding residual stress of the hoop structure were studied. The results show that the maximum residual stress of the outer plate surface of the hoop structure decreases with the increase of the welding energy, the thickness of the laminate, the width of the weld seam, the welding speed, and the radius of the container. Based on the results of numerical simulation, the ternary first-order equations of the maximum residual stress of the hoop structure with respect to the welding speed, the thickness of the laminate, and the width of the weld seam were established. Then, the optimal welding parameters were obtained by optimizing the equations, which provided an important basis for the safe use and optimal design of the welding hoop structure.

An Efficient Modelling Approach for Predicting Residual Stress in Power-Beam Welds

2019 ◽  
Author(s):  
Graeme Horne ◽  
Danny Thomas ◽  
Andrew Collett ◽  
Andrew Clay ◽  
Martin Cott ◽  
...  
Keyword(s):  
Residual Stress ◽  
Structural Integrity ◽  
Welding Residual Stress ◽  
Contour Method ◽  
Element Analysis ◽  
Stress Measurements ◽  
316L Austenitic Stainless Steel ◽  
Important Input ◽  
Integrity Assessments ◽  
Modelling Approach

Abstract The prediction of welding residual stress in components is often an important input to structural integrity assessments. An efficient modelling approach was developed for predicting residual stress in power-beam welds, including validation against residual stress measurements. Specifically, sequentially coupled thermo-mechanical finite element analysis was conducted using a simplified heat source that was tuned to the observed fusion zone from a weld macrograph and thermocouple data for a series of electron beam welds in 316L austenitic stainless steel with a variety of geometries. The predicted residual stresses were compared with contour method and neutron diffraction residual stress measurements.

Crack Extension Effects on Welding Residual Stress in Fitness for Service Assessment

2013 ◽  
Author(s):  
H. Chong Rhee
Keyword(s):  
Residual Stress ◽  
Driving Force ◽  
Crack Extension ◽  
Welding Residual Stress ◽  
Stress Release ◽  
Crack Driving Force ◽  
Defect Assessment ◽  
Standard Procedures ◽  
Growing Crack ◽  
Force Calculation

In the fitness for service assessment of a welded component with crack like defect, the current industry practices treat the welding residual stress in the same way as the applied operating stress in calculating the crack driving force. Although a growing crack should release the welding residual stress, the same initial residual stress is used in calculating the stress intensity factor solution regardless of the crack depth. Such procedures should result in too conservative solutions, since the crack extension effect on welding residual stress release is ignored in the crack driving force calculation. The present paper discusses the current state of the industry code and standard procedures for welded component defect assessment with a practical example problem solution, along with detailed discussions on the effects of crack growth on the welding residual stress. The objective of the paper is to motivate the industry to improve the code and standard procedures for the weld defect assessment. Also it presents a comparison of crack-like defect assessment results between the current industry procedure and one of newly proposed crack driving force calculation procedures for a crack growing in welding residual stress field, considering the welding residual stress release effects of growing crack. Recommendations for improving the industry code and standard procedures for the weld area defect assessment are provided based the investigation.

scholarly journals Evaluation of U10Mo Fuel Plate Irradiation Behavior via Numerical and Experimental Benchmarking

2012 ◽  
Author(s):  
Samuel J. Miller ◽  
Hakan Ozaltun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
3D Models ◽  
Creep Model ◽  
Element Analysis ◽  
Dimensional Changes ◽  
3 Dimensional ◽  
Out Of Plane ◽  
2D And 3D ◽  
Irradiation Behavior

This article analyzes dimensional changes due to irradiation of monolithic plate-type nuclear fuel and compares results with finite element analysis of the plates during fabrication and irradiation. Monolithic fuel plates tested in the Advanced Test Reactor (ATR) at Idaho National Lab (INL) are being used to benchmark the performance of proposed fuel for several high power research reactors. Post-irradiation metallographic images of plates sectioned at the mid-plane were analyzed to determine dimensional changes of the fuel and the cladding response. A constitutive model of the fabrication process and irradiation behavior of the tested plates was developed using the general purpose commercial finite element analysis package, ABAQUS. Using calculated burn-up profiles of irradiated plates to model the power distribution and including irradiation behaviors such as swelling and irradiation enhanced creep, model simulations allow analysis of plate parameters that are either impossible or infeasible in an experimental setting. The development and progression of fabrication induced stress concentrations at the plate edges was of primary interest, as these locations have a unique stress profile during irradiation. Additionally, comparison between 2D and 3D models was performed to optimize analysis methodology. In particular, the ability of 2D and 3D models to account for out of plane stresses which result in 3-dimensional creep behavior that is a product of these components. Results show that assumptions made in 2D models for the out-of-plane stresses and strains cannot capture the 3-dimensional physics accurately and thus 2D approximations are not representative. Stress-strain fields are dependent on plate geometry and irradiation conditions, thus, if stress based criteria is used to predict plate behavior (as opposed to material impurities, fine micro-structural defects, or sharp power gradients), unique 3D finite element formulation for each plate is required.

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