Prediction of Weld Residual Stress in a PWR Pressurizer Surge Nozzle: A Proposed Fast Computational 3D Analysis Method and Influence of Its Heat Source Model

2012 ◽  
Author(s):  
Akira Maekawa ◽  
Atsushi Kawahara ◽  
Hisashi Serizawa ◽  
Hidekazu Murakawa
Keyword(s):  
Residual Stress ◽  
Heat Source ◽  
High Speed ◽  
Nuclear Regulatory Commission ◽  
Source Model ◽  
Round Robin ◽  
Welding Residual Stress ◽  
3D Analysis ◽  
Heat Source Model ◽  
Pressurized Water

Primary water stress corrosion cracking (PWSCC) generated in dissimilar metal welds is one of the safety issues in ageing pressurized water reactor piping systems. It is well known that analysis accuracy of cracking propagation due to PWSCC depends on welding residual stress conditions. The U.S. Nuclear Regulatory Commission carried out an international round robin program for welding residual stress analysis validation to evaluate the accuracy and uncertainty quantitatively. In this study, participation results in the round robin program were reported. The three-dimensional analysis based on a fast weld simulation using the Iterative Substructure Method was clarified to provide accurate results in a high-speed computation. Furthermore, the influence of different heat source models on analysis results was investigated. It was demonstrated that the residual stress and distortion calculated using the moving heat source model were more accurate.

Prediction of Weld Residual Stress in a Pressurized Water Reactor Pressurizer Surge Nozzle

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Akira Maekawa ◽  
Atsushi Kawahara ◽  
Hisashi Serizawa ◽  
Hidekazu Murakawa
Keyword(s):  
Residual Stress ◽  
Heat Source ◽  
High Speed ◽  
Nuclear Regulatory Commission ◽  
Round Robin ◽  
Welding Residual Stress ◽  
3D Analysis ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor

Primary water stress corrosion cracking (PWSCC) phenomenon in dissimilar metal welds is one of the safety issues in ageing pressurized water reactor (PWR) piping systems. It is well known that analysis accuracy of cracking propagation due to PWSCC depends on welding residual stress conditions. The U.S. Nuclear Regulatory Commission (NRC) and the Electric Power Research Institute (EPRI) carried out an international round robin validation program to evaluate and quantify welding residual stress analysis accuracy and uncertainty. In this paper, participation results of the authors in the round robin program were reported. The three-dimensional (3D) analysis based on a fast weld simulation using an iterative substructure method (ISM), was shown to provide accurate results in a high-speed computation. Furthermore, the influence of different heat source models on analysis results was investigated. It was demonstrated that the residual stress and distortion calculated using the moving heat source model were more accurate.

Summary of Finite Element (FE) Sensitivity Studies Conducted in Support of the NRC/EPRI Welding Residual Stress (WRS) Program

2012 ◽  
Author(s):  
Matthew Kerr ◽  
Howard J. Rathbun
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Degradation Mechanism ◽  
Nuclear Regulatory Commission ◽  
Round Robin ◽  
Welding Residual Stress ◽  
Pressurized Water ◽  
Data Set ◽  
Strain Behavior ◽  
Sensitivity Studies

The U.S. Nuclear Regulatory Commission (NRC) and the Electric Power Research Institute (EPRI) are working cooperatively under an addendum to the ongoing memorandum of understanding to validate welding residual stress (WRS) predictions in pressurized water reactor (PWR) primary cooling loop components containing dissimilar metal (DM) welds. These stresses are of interest as DM welds in PWRs are susceptible to primary water stress corrosion cracking (PWSCC) and tensile weld residual stresses are the primary driver of this degradation mechanism. The NRC/EPRI weld residual stress (WRS) analysis validation program consists of four phases, with each phase increasing in complexity from laboratory size specimens to component mock-ups and ex-plant material. This paper focuses on Phase 2 of the WRS program that included an international Finite Element (FE) WRS round robin and experimental residuals stress measurements using the Deep Hole Drill (DHD) method on pressurizer surge nozzle mock-up. Characterizing variability in the round robin data set is difficult, as there is significant scatter in the data set and the WRS profile is dependent on the form of the material hardening law assumed. The results of this study show that, on average, analysts can develop WRS predictions that are a reasonable estimate for actual configurations as quantified by measurements. Sensitivity studies assist in determining which input parameters provide significant impact on WRSs, with thermal energy input, post-yield stress-strain behavior, and treatment of strain hardening have the greatest impact on DM WRS distributions.

NRC Welding Residual Stress Validation Program International Round Robin Program and Findings

2011 ◽  
Author(s):  
Howard J. Rathbun ◽  
Lee F. Fredette ◽  
Paul M. Scott ◽  
Aladar A. Csontos ◽  
David L. Rudland
Keyword(s):  
Residual Stress ◽  
Degradation Mechanism ◽  
Nuclear Regulatory Commission ◽  
Round Robin ◽  
Welding Residual Stress ◽  
Pressurized Water ◽  
Primary Driver ◽  
International Round ◽  
Standard Deviations ◽  
Regulatory Commission

The U.S. Nuclear Regulatory Commission (NRC) and the Electric Power Research Institute (EPRI) are working cooperatively under a memorandum of understanding to validate welding residual stress (WRS) predictions in pressurized water reactor (PWR) primary cooling loop components containing dissimilar metal (DM) welds. These stresses are of interest as DM welds in PWRs are susceptible to primary water stress corrosion cracking (PWSCC) and tensile weld residual stresses are the primary driver of this degradation mechanism. The NRC/EPRI weld residual stress (WRS) analysis validation program consists of four phases, with each phase increasing in complexity from laboratory size specimens to component mock-ups and cancelled-plant material. This paper discusses Phase 2 of the WRS characterization program involving an international round robin analysis project in which participants analyzed a prototypic reactor coolant pressure boundary component. Mock-up fabrication, WRS measurements and comparison with predicted stresses through the DM weld region are described. The results of this study show that, on average, analysts can develop WRS predictions that are a reasonable estimate for actual configurations as quantified by measurements. However, the scatter in predicted results from analyst to analyst can be quite large. For example, in this study, the scatter in WRSs through the centerline of the main DM weld (prior to stainless steel weld application) predicted by analysts is approximately +/− 200 to 300 MPa at 3 standard deviations for axial stresses and +/− 300 to 400 MPa at 3 standard deviations for hoop stresses. Sensitivity studies that vary important parameters, such as material hardening behavior, can be used to bound such large variations.

Influences of heat source model on welding residual stress and distortion in a multi-pass J-groove joint

2009 ◽  
Vol 46 (4) ◽  
pp. 987-995 ◽  
Author(s):  
Shoichi Kiyoshima ◽  
Dean Deng ◽  
Kazuo Ogawa ◽  
Nobuyoshi Yanagida ◽  
Koichi Saito
Keyword(s):  
Residual Stress ◽  
Heat Source ◽  
Source Model ◽  
Welding Residual Stress ◽  
Heat Source Model

scholarly journals Novel Calibration Strategy for Validation of Finite Element Thermal Analysis of Selective Laser Melting Process Using Bayesian Optimization

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4948
Author(s):  
Masahiro Kusano ◽  
Houichi Kitano ◽  
Makoto Watanabe
Keyword(s):  
Thermal Analysis ◽  
Finite Element ◽  
Heat Source ◽  
Selective Laser Melting ◽  
High Speed ◽  
Thermal Analyses ◽  
Source Model ◽  
Bayesian Optimization ◽  
Laser Melting ◽  
Heat Source Model

Selective laser melting (SLM) produces a near-net-shaped product by scanning a concentrated high-power laser beam over a thin layer of metal powder to melt and solidify it. During the SLM process, the material temperature cyclically and sharply rises and falls. Thermal analyses using the finite element method help to understand such a complex thermal history to affect the microstructure, material properties, and performance. This paper proposes a novel calibration strategy for the heat source model to validate the thermal analysis. First, in-situ temperature measurement by high-speed thermography was conducted for the absorptivity calibration. Then, the accurate simulation error was defined by processing the cross-sectional bead shape images by the experimental observations and simulations. In order to minimize the error, the optimal shape parameters of the heat source model were efficiently found by using Bayesian optimization. Bayesian optimization allowed us to find the optimal parameters with an error of less than 4% within 50 iterations of the thermal simulations. It demonstrated that our novel calibration strategy with Bayesian optimization can be effective to improve the accuracy of predicting the temperature field during the SLM process and to save the computational costs for the heat source model optimization.

Study on Distributed Properties of Welding Residual Stress in Bridge Nodes

2014 ◽  
Vol 501-504 ◽  
pp. 1166-1169
Author(s):  
Jia Liu ◽  
Run Chang Zhang ◽  
Wei Lian Qu ◽  
Li Jiang
Keyword(s):  
Residual Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Source Model ◽  
Welding Residual Stress ◽  
Welding Parameters ◽  
Heat Source Model ◽  
Lateral Direction ◽  
Welding Procedure ◽  
Welding Direction

The distributed properties of residual stress in bridge nodes have been investigated in the paper. Based on some bridge node, the three dimensional thermodynamics finite element model has been established, meanwhile, the double ellipsoidal distributed heat source model are used to simulate the whole welding procedure of bridge nodes according to the welding parameters. Thus, the distributed regularities of residual stress of bridge node have been obtained. Simulating results show that the residual stresses distribute uniformly in the welding direction, and the max value reaches the yield strength of steel Q345qD. Besides, the residual stress in the lateral direction reaches the max value in the place of welding district, and decreases rapidly when far away from the welds.

Numerical Simulation of the Prestressed Laser Welding of 7075－T7451 Aluminum Alloy Sheet

2010 ◽  
Vol 431-432 ◽  
pp. 13-16 ◽  
Author(s):  
Hong Feng Wang ◽  
Dun Wen Zuo ◽  
Hong Miao ◽  
Hong Jun Wang
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Welding Process ◽  
Source Model ◽  
Alloy Sheet ◽  
Welding Residual Stress ◽  
Aluminum Alloy Sheet ◽  
Heat Source Model ◽  
Element Simulation ◽  
Input Model

The heat source model and the heat input model were built by analyzing welding process. The rationalities of model were verified by finite element simulation. The method of prestressed welding was employed in order to reduce welding residual stress. The welding residual stress would be widely impacted by imposed prestress of 90% yield strength welding. At the same time the propagation of welding heat cracking in the heat-affected zone was properly controlled by prestressed welding.

Comparison of Welding Residual Stress Solutions for Control Rod Drive Mechanism Nozzles

2007 ◽  
Author(s):  
D. Rudland ◽  
Y. Chen ◽  
T. Zhang ◽  
G. Wilkowski ◽  
J. Broussard ◽  
...  
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Residual Stresses ◽  
Nuclear Regulatory Commission ◽  
Welding Residual Stress ◽  
Pressurized Water ◽  
Control Rod ◽  
Drive Mechanism ◽  
Time Period ◽  
Regulatory Commission

In the last 7 years, the incidences of cracking in Alloy 600 control rod drive mechanism (CRDM) tubes and their associated welds have increased significantly. The cracking mechanism has been attributed to pressurized water stress corrosion cracking (PWSCC) and has been shown to be driven by welding residual stresses and operational stresses in the weld region. During this time period, both the industry and the US Nuclear Regulatory Commission have been conducting detailed welding simulation analyses to predict the magnitude of these stresses in both the weld and tube material. To this point, a direct comparison of these analysis methodologies and results has not been made. In this paper, weld residual stress results from U.S. industry (conducted by Dominion Engineering) and the U.S. NRC (conducted by Engineering Mechanics Corporation of Columbus) for a steep angle (53 degrees) CRDM nozzle are compared. This comparison was performed for different yield strength tube materials, however only the low yield strength results are presented in this paper. The comparison illustrates the effect of weld analyses assumptions and suggests that simplifications in the analyses, i.e., lumping weld passes or material property assumptions, may lead to high predicted weld residual stresses.

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