Ductile Tearing Prediction of Ferritic Pipe Material by Gtn Model for Atlas+ European Project

2021 ◽  
Author(s):  
Kiminobu Hojo ◽  
Takatoshi Hirota ◽  
Naoki Ogawa ◽  
Satoshi Kumagai
Keyword(s):  
Pipe Material ◽  
Gtn Model ◽  
Ductile Tearing ◽  
European Project

Ductile Tearing Prediction of Ferritic Pipe Material by GTN Model for ATLAS+ European Project

2020 ◽  
Author(s):  
Kiminobu Hojo ◽  
Takatoshi Hirota ◽  
Naoki Ogawa ◽  
Satoshi Kumagai
Keyword(s):  
Fracture Behavior ◽  
Structural Integrity ◽  
Assessment Tools ◽  
Pipe Material ◽  
Work Package ◽  
Gtn Model ◽  
Term Operation ◽  
Integrity Assessment ◽  
European Project

Abstract The main objective and mission of the European project ATLAS+ (Advanced Structural Integrity Assessment Tools for Safe Long Term Operation) are to address the remaining technology gaps for the safe and long term operation of nuclear reactor pressure coolant boundary systems. This project includes the development and validation of advanced simulation tools based on fracture mechanics methods using physically based mechanistic models. In the Work Package 3 (WP3), benchmark calculations using different available models are conducted to investigate the accuracy and the capability of the different models for ductile crack growth of different constraint condition, such as laboratory specimens and piping structure, which were tested in the Work Package 1 (WP 1). The authors joined the WP3 activity and investigated the effect of the parameters of the GTN (Gurson-Tvergaard-Needleman) model on the fracture behavior of the specimens. In this paper, the parameters of the GTN model were calibrated to simulate the fracture behavior of CT specimens, notched tensile (NT) specimens and single edge notched tensile (SENT) specimens of ferritic pipe material and the applicability of the GTN model. The adjusted parameters by the CT specimen predicted the fracture behavior of the SENT specimens, but did not those of the NT specimens. The adjusted parameters by the CT specimens were applied to the piping structure mock-up and they predicted the maximum load in high accuracy.

scholarly journals European Project ATLAS+: Small and Large Scale Ductile Tearing Experiments on Ferritic Steel WB36 to Study Transferability of Material Ductile Properties

2019 ◽  
Author(s):  
Anna Dahl ◽  
Dominique Moinereau ◽  
Patrick Le Delliou ◽  
Willy Vincent
Keyword(s):  
Ferritic Steel ◽  
Large Scale ◽  
Structural Integrity ◽  
Assessment Tools ◽  
Test Facility ◽  
Small Scale ◽  
Feed Water ◽  
Ductile Tearing ◽  
Integrity Assessment ◽  
European Project

Abstract The 4-years European project ATLAS+ (Advanced Structural Integrity Assessment Tools for Safe long Term Operation) has been launched in June 2017. One of its objectives is to study the transferability of material ductile properties from small scale specimens to large scale components and validate some advanced tools for structural integrity assessment. The study of properties transferability is based on a wide experimental programme which includes a full set of fracture experiments conducted on conventional fracture specimens and large scale components (mainly pipes). Three materials are considered in the programme : a ferritic steel WB36 typical from secondary feed water line in German PWR reactors, an aged stainless steel austenitic weld representative of EPR design and a typical VVER austenitic dissimilar weld (DMW). This paper describes the experimental work conducted on the ferritic steel WB 36 (15NiCuMoNb5) and summarizes the experimental results available after 2 years of work. Numerous mechanical tests have been conducted on a wide panel of fracture mechanics specimens for a full characterization of the ferritic steel: Tensile properties, Hardness, Charpy Energy, pre-cracked Charpy PCC, Master curve on CT and SENT specimens, ductile tearing properties on CT and SENT specimens. In parallel, it is planned to test three 4PB large scale tests on pipings (FP1, FP2 and FP3) at room temperature on the EDF test facility with 3 configurations (shape, size and location) of cracks: through wall crack (TWC), internal and external ½ elliptical cracks. Progress of these large scale experiments is described including first results.

Effects of Side Groove on Fracture Toughness

2015 ◽  
Author(s):  
Ho-Wan Ryu ◽  
Hune-Tae Kim ◽  
Jae-Jun Han ◽  
Yun-Jae Kim ◽  
Jong-Sung Kim ◽  
...  
Keyword(s):  
Test Data ◽  
Fracture Strain ◽  
Failure Criteria ◽  
Compact Tension ◽  
Damage Analysis ◽  
Pipe Material ◽  
Ductile Tearing ◽  
Different Shapes ◽  
Strain Model ◽  
Good Agreement

This paper describes ductile tearing simulation for compact tension (C(T)) specimens using FE damage analysis based on the stress-modified fracture strain model. The side groove effect on J-resistance curve was estimated by experimental and analytical ways. In this paper, SA508 Grade 1A low alloy steel pipe material was considered. Tensile and C(T) specimens are simulated to determine the failure criteria with finite element method. Then, different shapes of C(T) specimens are analysed and the results from simulations are compared with test data for verification of proposed method. Overall, the predicted simulation results show good agreement with test data.

Development of GTN Model Parameters for Simulating Ductile Fracture Behavior of X 70 Carbon Steel SENT Specimens

2019 ◽  
Author(s):  
Sung Ho Yoon ◽  
Tae-Young Ryu ◽  
Moon Ki Kim ◽  
Jae-Boong Choi ◽  
Ik-Joong Kim
Keyword(s):  
Carbon Steel ◽  
Ductile Fracture ◽  
Fracture Behavior ◽  
Boundary Effect ◽  
Test Method ◽  
Pipe Material ◽  
Single Edge ◽  
Fracture Characteristics ◽  
Gtn Model ◽  
Senb Specimen

Abstract Single-Edge-Notched-Bending (SENB) specimen is mainly used for fracture characteristics test of pipe material. However, there is also a disadvantage in that it does not sufficiently simulate the fracture characteristics of thin pipes due to the difference in boundary effect between the SENB specimen and the actual pipe. The Single-Edge-Notched-Tensile (SENT) specimen can be used as complementary test method due to its less boundary effect compared to the SENB specimen. In this study, the SENT specimen which are fabricated with API X 70 carbon steel was simulated ductile fracture behavior by using finite-element-analysis (FEA). To simulate ductile fracture behavior, Gurson-Tvergaard-Needleman (GTN) model was applied. GTN model is a kind of damage model that describes the behavior of ductile fracture through three steps of void changes : nucleation, growth, and coalescence. And GTN model is composed of three constitutive equations and nine parameters. In order to develop the GTN ductile fracture model for API X 70 carbon steel, five kinds of tensile specimen tests were simulated by FEA. In addition, we analyzed the influence of parameters of GTN model through analysis and developed optimal material parameters for API X 70 carbon steel. Finally, the ductile fracture behavior of the SENT specimen was simulated and the FEA results of SENT specimen was compared with actual SENT specimen test.

Effect of pipe expansion on the redistribution of residual stresses after molding

2020 ◽  
Vol 10 (2) ◽  
pp. 122-126
Author(s):  
Nikolay A. Makhutov ◽  
◽  
Dmitry A. Neganov ◽  
Eugeny P. Studenov ◽  
◽  
...  
Keyword(s):  
Residual Stresses ◽  
Strain Distribution ◽  
Strain State ◽  
Stress And Strain ◽  
Cylindrical Shape ◽  
Pipe Material ◽  
Pipe Expansion ◽  
Calculation Results ◽  
Residual Deformations ◽  
Stress And Strain Distribution

In the factory, pipes for trunk oil and oil product pipelines are obtained by molding and welding. To ensure a cylindrical shape and reduce technological residual stresses, expansion technology is used. Pipe expansion causes a significant change in the values of residual deformations and stresses. The article presents both the calculation results and graphs regarding stress and strain distribution during bending of the stock and their redistribution after expansion. Based on the calculation results, the final total values of residual stresses and residual deformations caused by bending and expansion were stated to be important components of the stress-strain state observed in pipelines being operated under cyclic loading, as well as those used in assessing how degradation affects the ductility of the pipe material. These factors were concluded as being reasonably taken into account when performing verification calculations regarding long-running pipelines if, based on their diagnostics and analysis, their state does not meet modern strength requirements.

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