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Finite Element Plastic Limit Loads of Complex Cracks in Pipes With Two-Layered Materials
Da-Som Jeon1, Nam-Su Huh1, Do-Jun Shim2
1Department of Mechanical System Design Engineering, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul, 01811, South Korea.
Journal of Pressure Vessel Technology
|January 13, 2021
Summary
This study uses 3D finite element analysis to determine the load capacity of cracked nuclear pipes with two material layers. Results aid in assessing critical crack lengths for leak-before-break analyses.
Area of Science:
- Structural Engineering
- Materials Science
- Nuclear Engineering
Background:
- Nuclear piping systems with dissimilar metal welds (DMW) often utilize weld overlays, creating two-layered material structures.
- Complex cracks, such as combined through-wall and surface cracks, can compromise the integrity of these pipes.
- Accurate assessment of plastic limit loads is crucial for ensuring the safety and reliability of nuclear piping.
Purpose of the Study:
- To investigate the plastic limit loads of pipes with complex cracks in two-layered materials.
- To determine the maximum load-carrying capacity and critical crack lengths for such pipes.
- To provide data applicable to leak-before-break (LBB) assessments in nuclear piping.
Main Methods:
- Detailed three-dimensional (3D) finite element (FE) limit analyses were performed.
- Systematic consideration of pipe thickness, crack depth and length, and material strength mismatch.
- Loading conditions included axial tension, global bending moment, and internal pressure.
Main Results:
- FE plastic limit loads were calculated for complex-cracked pipes with two-layered materials.
- FE results were validated against existing solutions for single-material pipes and compared with two-layered material data.
- A simplified approach using an equivalent single material based on weighted averages was proposed.
Conclusions:
- The study provides critical data for evaluating the structural integrity of cracked nuclear pipes with weld overlays.
- The proposed simplified approach offers a potential method for predicting plastic limit loads in two-layered materials.
- Findings support enhanced safety assessments and LBB analyses for nuclear piping systems.
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