ML18270A092: Difference between revisions
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| number = ML18270A092 | | number = ML18270A092 | ||
| issue date = 09/24/2018 | | issue date = 09/24/2018 | ||
| title = | | title = Exploring Capabilities of Xfem for Use in Flaw Evaluations | ||
| author name = Facco G | | author name = Facco G | ||
| author affiliation = NRC/RES/DE/CIB | | author affiliation = NRC/RES/DE/CIB | ||
| Line 16: | Line 16: | ||
=Text= | =Text= | ||
{{#Wiki_filter:EXPLORING CAPABILITIES OF XFEM FOR USE IN FLAW EVALUATIONS Public Meeting 9/24/2018 Giovanni Facco RES/DE/CIB | {{#Wiki_filter:EXPLORING CAPABILITIES OF XFEM FOR USE IN FLAW EVALUATIONS 1 | ||
Public Meeting 9/24/2018 Giovanni Facco RES/DE/CIB | |||
Objectives Introduce Plan to Investigate Use of xFEM Methods to Investigate PWSCC Growth | Objectives Introduce Plan to Investigate Use of xFEM Methods to Investigate PWSCC Growth | ||
- Motivation, Plan, Preliminary Results | |||
- Feedback Discuss International Efforts/Collaboration 2 | |||
Motivation | Motivation | ||
| Line 28: | Line 29: | ||
Current FEA Application | Current FEA Application | ||
- Model WRS in complex geometries by simulating weld parameters 1. | |||
Perform thermal analysis 2. | |||
Impose thermal history in mechanical analysis to generate WRS profile | |||
- Multiple weld histories can be explored without the need for new model or re-meshing | |||
- These Results can then be used to calculate crack growth rates No Repair Large ID Repair OD Repair Root Repair No Repair Large ID Repair OD Repair Root Repair Thermal Model Mechanical Model 4 | |||
Traditional FEA vs xFEM Traditional FEA | Traditional FEA vs xFEM Traditional FEA Results in very accurate SIF and stress states Requires re-meshing for any change crack size or geometry Analysis usually limited to idealized crack shapes and planar crack growth due to complexity of models xFEM Mesh-independent analysis of discontinuities and singularities Can quickly calculate SIF of multiple cracks and crack lengths without major modifications to model Can model realistic 3D crack growth without re-meshing Traditional FEA Crack Growth 5 | ||
Current Crack Growth Rate Methods | Current Crack Growth Rate Methods | ||
* Crack growth calculations based on ASME Methodology | * Crack growth calculations based on ASME Methodology | ||
- 2D approximations | |||
- Uses idealized crack shape and growth model (semi-elliptical) | |||
- Assumes planar crack growth, perpendicular to pipe wall | |||
- WRS profile for crack growth is path dependent and user defined 6 | |||
Research Project Plan PWSCC Crack Growth Development | Research Project Plan PWSCC Crack Growth Development | ||
- Reproduce PWSCC Growth Behaviors | |||
- Investigate Cracking Property Response | |||
- Investigate Simulation Parameter Response Model Material Behavior | |||
- Develop material property relationships using experimental component geometry (e.g. C(T) | |||
Specimen) to benchmark model response. | Specimen) to benchmark model response. | ||
Industry Relevant Models | Industry Relevant Models | ||
- Compared xFEM results to similar industry relevant models evaluated using traditional methods. | |||
7 | 7 | ||
Methodology | Methodology ABAQUS can simulate fatigue crack growth using a Paris Law type relationship | ||
= | |||
ASME Code analysis determines PWSCC crack growth behavior using a similar power law relationship | |||
= | |||
G and K are interrelated by a linear relationship in LEFM | |||
= | |||
2 | |||
where E'=E for plane stress and | where E'=E for plane stress and = | ||
(12) for plane strain 8 | |||
Initial Results Comparison of Nondimensional Stress Intensity Factors Contour ABAQUS Benchmark RES Model Difference | |||
% Error (Handbook Value of 2.826) 2 2.8537 2.8712 0.61098 1.599 3 | |||
2.9643 2.9815 0.57967 5.504 4 | |||
3.0027 2.9956 0.23679 6.001 5 | |||
2.9696 2.9726 0.10218 5.189 Fatigue Crack Growth (Video) | |||
Stress Intensity Factor Calculations 2D Single Edge Notch | |||
= | |||
9 | |||
Status | Status | ||
| Line 85: | Line 85: | ||
International Benchmarking Efforts | International Benchmarking Efforts | ||
* In cooperation with Committee on the Safety of Nuclear Installations (CSNI) the NRC is taking part in a technical round robin project exploring X-FEM Capabilities. | * In cooperation with Committee on the Safety of Nuclear Installations (CSNI) the NRC is taking part in a technical round robin project exploring X-FEM Capabilities. | ||
- Multinational group (Public and Private, 12 Countries) | |||
- Focus is on an preliminary comparison of the X-FEM capabilities of the different codes used in the nuclear industry | |||
- Goal is to share Methodology and Results in order to evaluate capabilities and develop best practices. | |||
11 | 11 | ||
International Benchmarking Efforts | International Benchmarking Efforts | ||
* Three benchmark problems | * Three benchmark problems | ||
- Surface Crack in Plate | |||
- Embedded Crack in Plate Subjected to Shear Load | |||
- Underclad Crack in Core Shell of an RPV | |||
* Evaluate stationary cracks | * Evaluate stationary cracks | ||
* Thermal and mechanical loading | * Thermal and mechanical loading | ||
| Line 101: | Line 101: | ||
Summary | Summary | ||
* Developing xFEM Techniques | * Developing xFEM Techniques | ||
- Investigate Use of xFEM for PWSCC Growth | |||
- International Collaboration Efforts | |||
* Feedback 13}} | * Feedback 13}} | ||
Latest revision as of 12:50, 5 January 2025
| ML18270A092 | |
| Person / Time | |
|---|---|
| Issue date: | 09/24/2018 |
| From: | Giovanni Facco NRC/RES/DE/CIB |
| To: | |
| Michael Benson | |
| Shared Package | |
| ML18270A088 | List: |
| References | |
| Download: ML18270A092 (13) | |
Text
EXPLORING CAPABILITIES OF XFEM FOR USE IN FLAW EVALUATIONS 1
Public Meeting 9/24/2018 Giovanni Facco RES/DE/CIB
Objectives Introduce Plan to Investigate Use of xFEM Methods to Investigate PWSCC Growth
- Motivation, Plan, Preliminary Results
- Feedback Discuss International Efforts/Collaboration 2
Motivation
- RES has identified that future PWSCC flaw evaluations may involve 3D Finite Element Models of crack growth with complex stresses in asymmetrical components.
- In order to be able to properly evaluate this kind of model RES plans to continue building upon its computational expertise in this potentially regulatory significant area.
- Developing these capabilities and sharing what we learn we hope to improve and modernize how these issues are evaluated in the future 3
Current FEA Application
- Model WRS in complex geometries by simulating weld parameters 1.
Perform thermal analysis 2.
Impose thermal history in mechanical analysis to generate WRS profile
- Multiple weld histories can be explored without the need for new model or re-meshing
- These Results can then be used to calculate crack growth rates No Repair Large ID Repair OD Repair Root Repair No Repair Large ID Repair OD Repair Root Repair Thermal Model Mechanical Model 4
Traditional FEA vs xFEM Traditional FEA Results in very accurate SIF and stress states Requires re-meshing for any change crack size or geometry Analysis usually limited to idealized crack shapes and planar crack growth due to complexity of models xFEM Mesh-independent analysis of discontinuities and singularities Can quickly calculate SIF of multiple cracks and crack lengths without major modifications to model Can model realistic 3D crack growth without re-meshing Traditional FEA Crack Growth 5
Current Crack Growth Rate Methods
- Crack growth calculations based on ASME Methodology
- 2D approximations
- Uses idealized crack shape and growth model (semi-elliptical)
- Assumes planar crack growth, perpendicular to pipe wall
- WRS profile for crack growth is path dependent and user defined 6
Research Project Plan PWSCC Crack Growth Development
- Reproduce PWSCC Growth Behaviors
- Investigate Cracking Property Response
- Investigate Simulation Parameter Response Model Material Behavior
- Develop material property relationships using experimental component geometry (e.g. C(T)
Specimen) to benchmark model response.
Industry Relevant Models
- Compared xFEM results to similar industry relevant models evaluated using traditional methods.
7
Methodology ABAQUS can simulate fatigue crack growth using a Paris Law type relationship
=
ASME Code analysis determines PWSCC crack growth behavior using a similar power law relationship
=
G and K are interrelated by a linear relationship in LEFM
=
2
where E'=E for plane stress and =
(12) for plane strain 8
Initial Results Comparison of Nondimensional Stress Intensity Factors Contour ABAQUS Benchmark RES Model Difference
% Error (Handbook Value of 2.826) 2 2.8537 2.8712 0.61098 1.599 3
2.9643 2.9815 0.57967 5.504 4
3.0027 2.9956 0.23679 6.001 5
2.9696 2.9726 0.10218 5.189 Fatigue Crack Growth (Video)
Stress Intensity Factor Calculations 2D Single Edge Notch
=
9
Status
- Successfully used ABAQUS simplified fatigue crack growth method, to grow a crack in a static stress field (externally applied or internal) in a 2D model
- Developed preliminary parameter relationships between ABAQUS fatigue model and PWSCC model
- Cracking parameter response (G & K) for 2D models shows good agreement with handbook values 10
International Benchmarking Efforts
- In cooperation with Committee on the Safety of Nuclear Installations (CSNI) the NRC is taking part in a technical round robin project exploring X-FEM Capabilities.
- Multinational group (Public and Private, 12 Countries)
- Focus is on an preliminary comparison of the X-FEM capabilities of the different codes used in the nuclear industry
- Goal is to share Methodology and Results in order to evaluate capabilities and develop best practices.
11
International Benchmarking Efforts
- Three benchmark problems
- Surface Crack in Plate
- Embedded Crack in Plate Subjected to Shear Load
- Underclad Crack in Core Shell of an RPV
- Evaluate stationary cracks
- Thermal and mechanical loading
- Static and transient conditions 12
Summary
- Developing xFEM Techniques
- Investigate Use of xFEM for PWSCC Growth
- International Collaboration Efforts
- Feedback 13