Fracture toughness prediction of thermally-aged welded stainless steels using multi-axial fracture strain FE damage model

2019 ◽  
Vol 2019 (0) ◽  
pp. OS1310
Author(s):  
Gyogeun YOUN ◽  
Yasufumi MIURA ◽  
Yunjae KIM
Keyword(s):  
Fracture Toughness ◽  
Stainless Steels ◽  
Fracture Strain ◽  
Damage Model ◽  
Axial Fracture

A Method to Quantify Thermal Aging Effect on Fracture Toughness of Cast Stainless Steels Using Small Punch Test

2014 ◽  
Author(s):  
Jun-Young Jeon ◽  
Dong-Il Ryu ◽  
Yun-Jae Kim ◽  
Mi-Yeon Lee ◽  
Jin-Weon Kim
Keyword(s):  
Fracture Toughness ◽  
Test Data ◽  
Stainless Steels ◽  
Fracture Strain ◽  
Fracture Toughness Test ◽  
Small Punch ◽  
Fracture Simulation ◽  
Toughness Test ◽  
Axial Fracture ◽  
Strain Model

In this study, a method to predict fracture toughness of aged cast austenitic stainless steels (CASSs) using small punch (SP) test and finite element (FE) analysis is proposed. Grade CF8M is considered and thermally aged up to 5,000 hours at 400°C. SP tests and fracture toughness test using compact tension (C(T)) specimen are conducted with virgin (unaged) and aged CF8M. FE analyses performed in this study use ductile fracture simulation technique with ‘the multi-axial fracture strain model’. The multi-axial fracture strain model for each aged CF8M are determined from SP test data and FE analyses. Fracture toughness of aged CF8M are predicted by conducting fracture toughness test simulations using FE damage analyses. Predicted fracture toughness results are compared with C(T) data to validate the method suggested in this study. The predicted initiation toughness values are predicted well and fracture toughness values are slightly conservative compared to test data.

Ductile Tearing Simulation of Circumferential Cracked Pipe Under Cyclic Loading Using Damage Criteria Determined by Monotonic Pipe Test Data

2018 ◽  
Author(s):  
Jin-Ha Hwang ◽  
Gyo-Geun Youn ◽  
Naoki Miura ◽  
Yun-Jae Kim
Keyword(s):  
Fracture Toughness ◽  
Cyclic Loading ◽  
Ductile Fracture ◽  
Test Data ◽  
Strain Energy ◽  
Fracture Strain ◽  
Damage Model ◽  
Fracture Toughness Test ◽  
Ductile Tearing ◽  
Damage Criteria

To evaluate the structural integrity of nuclear power plant piping, it is important to predict ductile tearing of circumferential cracked pipe from the view point of Leak-Before-Break concept under seismic conditions. CRIEPI (Central Research Institute of Electric Power Industry) conducted fracture test on Japanese carbon steel (STS410) circumferential through-wall cracked pipes under monotonic or cyclic bending load in room temperature. Cyclic loading test conducted variable experimental conditions considering effect of stress ratio and amplitude. In the previous study, monotonic fracture pipe test was simulated by modified stress-strain ductile damage model determined by C(T) specimen fracture toughness test. And, ductile fracture of pipe under cyclic loading simulated using damage criteria based on fracture strain energy from C(T) specimen test data. In this study, monotonic pipe test result is applied to determination of damage model based on fracture strain energy, using finite element analysis, without C(T) specimen fracture toughness test. Ductile fracture of pipe under variable cyclic loading conditions simulates using determined fracture energy damage model from monotonic pipe test.

Energy-based numerical modeling of the strain rate effect on fracture toughness of SA508 Gr. 1a

2017 ◽  
Vol 52 (3) ◽  
pp. 177-189 ◽  
Author(s):  
Hyun-Suk Nam ◽  
Yun-Jae Kim ◽  
Jin-Weon Kim ◽  
Jong-Sung Kim
Keyword(s):  
Fracture Toughness ◽  
Strain Rate ◽  
Damage Model ◽  
Type Model ◽  
Fracture Toughness Test ◽  
Ductile Tearing ◽  
Rate Dependent ◽  
Energy Concept ◽  
Axial Fracture ◽  
Dynamic Loading Conditions

This article presents an energy-based method to simulate ductile tearing under dynamic loading conditions. The strain rate–dependent material properties are characterized by the Johnson–Cook-type model. The damage model is defined based on the multi-axial fracture strain energy concept. The proposed damage model is applied to simulate the fracture toughness test of SA508 Gr. 1a under four different test speeds. Simulated results show a good overall agreement with the experimental results.

Ductile Fracture Simulation of CRIEPI STPT 410 Pipe With Circumferential Crack

2014 ◽  
Author(s):  
Hyun-Suk Nam ◽  
Young-Ryun Oh ◽  
Jae-Jun Han ◽  
Chang-Young Oh ◽  
Yun-Jae Kim ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Fracture Strain ◽  
Damage Model ◽  
Full Scale ◽  
Ductile Crack ◽  
Size Dependent ◽  
Element Size ◽  
Ductile Crack Growth ◽  
Strain Model

This paper provides simulation of ductile crack growth in full-scale cracked pipe tests using an element-size dependent damage model. This method is based on the stress-modified fracture strain damage model. The stress-modified fracture strain model is determined to be incremental damage in terms of stress triaxiality and fracture strain for dimple fracture from tensile test result with FE analyses technique. To validate the proposed method, this research analyses STPT 410 cracked pipes test at 300°C taken from CRIEPI (Central Research Institute of Electric Power Industry). In order to calibrate the stress-modified fractures strain model, tensile tests and fracture toughness tests were compared with simulated results using element-size dependent damage model. Tensile specimen and fracture toughness specimen were extracted from STPT 410 steel pipe. The calibrated damage model predicts ductile crack growth in 5 type circumferential cracked pipes bending test. And these results were compared with the experimental results. The results show that the proposed method can simulate ductile crack growth in full-scale cracked pipe tests.

Fracture Mechanics Study on the Effects of Various Notch Radii by Using FE Analysis

2015 ◽  
Author(s):  
Zalikha Murni Abdul Hamid ◽  
Keun-Hyung Bae ◽  
Gyo-Geun Youn ◽  
Dae-Young Lee ◽  
Yun-Jae Kim ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Fracture Strain ◽  
Notch Root ◽  
Damage Model ◽  
Fe Analysis ◽  
Experiment Data ◽  
Apparent Fracture Toughness ◽  
Notch Root Radius ◽  
Plane Strain Deformation

This paper predicts the effects of notch root radius on the ductile fracture behavior of the structure through evaluation based on fracture mechanics concept. To understand the effects of notch radii on structure, FE analysis of J-integral for plane strain deformation fields with various size of notches were predicted. The fracture toughness of the specimens with various notch radii were determined by stress modified fracture strain damage model FE simulation that was established based on notched bar tensile test data. The simulated results were validated by comparison with the experiment data. Findings show that the value of apparent fracture toughness increases with the increase in the notch radii. Therefore, indicates the increase in the resistance to the crack propagation. Similar trend can be shown for both C(T) and M(T) specimen. Thus, shows that the proposed method can be used to obtain effects of various notch radii.

Quantification of the Material Ductility Effect on Notch Fracture Toughness Using Numerical Damage Analysis Method

2020 ◽  
Author(s):  
Eui-kyun Park ◽  
Gyo-Geun Youn ◽  
Yun-Jae Kim ◽  
Masayuki Kamaya
Keyword(s):  
Fracture Toughness ◽  
Fracture Resistance ◽  
Damage Model ◽  
Fe Analysis ◽  
Damage Analysis ◽  
Notch Radius ◽  
Cold Worked ◽  
Axial Fracture ◽  
Material Ductility ◽  
The Relationship

Abstract In this study, the finite element (FE) damage analysis based on the multi-axial fracture strain model was applied to investigate the effect of the material ductility on fracture resistance of notched defect. (The fracture toughness is used only for a cracked specimen and the fracture resistance is used for notched specimens throughout the paper.) To obtain the material property with different ductility, the tensile and fracture toughness tests of the cold-worked SUS316 were used. The damage model was determined from comparing the experimental data with simulated FE analysis results. Then the FE analysis was applied to calculate the fracture resistance according to the notch radius in each material. It shows that the slope of initiation resistance according to the notch radius was related to the material ductility. To quantify this effect of ductility, the relationship between notch fracture resistance and material tensile properties was confirmed.

Application of Energy-Based Damage Model to Simulate Ductile Fracture Under Cyclic Loading and Validation Against Piping System Test Data

2018 ◽  
Author(s):  
Gyo-Geun Youn ◽  
Hyun-Suk Nam ◽  
Hune-Tae Kim ◽  
Jong-Min Lee ◽  
Yun-Jae Kim
Keyword(s):  
Cyclic Loading ◽  
Ductile Fracture ◽  
Strain Energy ◽  
Loading Condition ◽  
Fracture Strain ◽  
Damage Model ◽  
Test Results ◽  
Cyclic Loading Condition ◽  
Low Cyclic Loading ◽  
Axial Fracture

In this paper, a method to predict ductile fracture under low cyclic loading condition is proposed. Then it is compared with test results of surface cracked pipes which is conducted by Battelle Institute. A&F nonlinear kinematic hardening model is adopted to describe material behavior under cyclic loading condition and energy-based damage model is applied to simulate ductile crack growth. The energy-based damaged model is depending on multi-axial fracture strain energy. To apply this model, two parameters should be determined from tensile and C(T) test results under monotonic loading condition. One is multi-axial fracture strain energy Wf and the other is critical damage value ωc. From the determined damaged model, it is enable to simulate surface cracked pipe tests under low cyclic loading condition.

J-R Curve Prediction of Pre-Strained Stainless Steel 316 Material Using FE Damage Analysis Method

2018 ◽  
Author(s):  
Jun-Min Seo ◽  
Ji-Soo Kim ◽  
Yun-Jae Kim
Keyword(s):  
Experimental Data ◽  
Fracture Toughness ◽  
Damage Model ◽  
Damage Analysis ◽  
Fracture Toughness Test ◽  
Toughness Test ◽  
Cold Worked ◽  
Axial Fracture ◽  
Stainless Steel 316 ◽  
Strain Model

In this study, a method to predict J-R curve of SUS316 material using FE damage analysis is proposed. As experimental data, tensile and fracture toughness test results of cold worked SUS316 are used. The damage model used in this study is multi-axial fracture strain model and the model is determined by simulating the tensile and fracture toughness test according to the procedure in R6 code [1]. A pre-strain constant is newly introduced to consider pre-strain damage caused by the pre-strain, and the damage for various degrees of pre-strain are calculated. As a result, the predicted J-R curves using FE damage model show good agreement with the experimental data.

EPRI P87

Alloy Digest ◽  
2011 ◽  
Vol 60 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Tensile Properties ◽  
Stainless Steels ◽  
Austenitic Stainless Steels

Abstract EPRI P87 is a MMA electrode designed for dissimilation joints between austenitic stainless steels (i.e. 304H) and a creep resisting CrMo alloy (i.e. P91). This datasheet provides information on composition and tensile properties as well as fracture toughness. It also includes information on joining. Filing Code: Ni-685. Producer or source: Metrode Products Ltd.

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