Comparison of J Resistance Curves From Toughness Testing Specimens With Those From Various Cracked Pipe Tests

2013 ◽  
Author(s):  
Jong-Hyun Kim ◽  
Jae-Jun Han ◽  
Yun-Jae Kim ◽  
Do-Jun Shim
Keyword(s):  
Damage Model ◽  
Fe Analysis ◽  
Contour Integral ◽  
Damage Analysis ◽  
Resistance Curve ◽  
Size Dependent ◽  
Element Size ◽  
Toughness Testing ◽  
Resistance Curves ◽  
J Estimation

J contour integral still has great importance to predict fracture of both small specimen and full-scaled pipes. However, it is difficult to obtain experimental J resistance curve of full-scaled pipes due to the differences of defect shape and complexity of loads. Due to the recent development of the FE damage analysis to predict fracture of full-scaled pipes, it is also possible to predict J resistance of full-scaled pipes. To use this FE damage model for fracture estimation, it is necessary to verify the validity of this model by compared with toughness testing specimens. In this paper, J resistance curves of full-scaled pipes using FE damage analysis were compared with various toughness testing specimens from Pipe Fracture Encyclopedia performed by Battelle. And the J contour integral were calculated from FE analysis using the element-size-dependent damage model recently proposed by the authors. Compared results showed that J calculation using FE damage analysis could be used for J-estimation of full-scaled pipes by compared with fracture toughness testing specimens.

Burst Pressure Prediction of Cracked Steam Generator Tube Using FE Damage Analysis

2015 ◽  
Author(s):  
Jun-Young Jeon ◽  
Yun-Jae Kim ◽  
Jin-Weon Kim
Keyword(s):  
Crack Propagation ◽  
Steam Generator ◽  
Test Data ◽  
Damage Model ◽  
Fe Analysis ◽  
Multiple Cracks ◽  
Outer Diameter ◽  
Damage Analysis ◽  
Element Size ◽  
Alloy 690

This paper predicts burst pressures of the steam generator tubes with multiple cracks using finite element (FE) damage analysis. Alloy 690(TT) tube (the outer diameter of 19.05 mm and the thickness of 1.07 mm) widely used in the nuclear power plant is considered in this study. Ductile failure at each element is predicted with the damage model known as ‘multi-axial fracture strain model’ as well as crack propagation is simulated by stress reduction technique in the FE analysis. Simplified ductile damage model for Alloy 690(TT) are determined using tube tensile test data and elastic-plastic FE analysis. FE damage analysis results are sensitive to the element size used in the crack propagation region. Using notched tube fracture test data, proper element size for Alloy 690(TT) is found. Single, collinear, parallel, non-aligned axial-cracks are considered in the simulations and the predicted burst pressures are compared with burst test data.

Quantification of the Complex Crack Geometry Effect On Fracture Resistance Using Strain Based FE Damage Analysis

2021 ◽  
Author(s):  
Seung-Jae Kim ◽  
Ho-Wan Ryu ◽  
Jin Weon Kim ◽  
Young-Jin Oh ◽  
Yun-Jae Kim
Keyword(s):  
Crack Length ◽  
Surface Crack ◽  
Crack Depth ◽  
Damage Model ◽  
Simulation Method ◽  
Resistance Curve ◽  
Crack Geometry ◽  
Model And Simulation ◽  
Resistance Curves ◽  
Complex Crack

Abstract This paper examines the effect of complex crack geometry on the J-resistance curves obtained by strain-based ductile tearing simulation of complex cracked tension (CC(T)) specimens. The damage model is determined by analyzing the results of a smooth bar tensile test and a C(T) specimen toughness test on an SA508 Gr.1a low-alloy steel at 316 ?. The validity of the damage model and simulation method is checked by comparing the fracture test data for two CC(T) specimen tests. To investigate the effect of the complex crack geometry on the crack growth profiles and J-resistance curves, two geometric parameters (namely, the through-wall crack length and the surface crack depth) are systematically varied. It is found that the J-resistance curves for the CC(T) specimens with various through-wall crack lengths and surface crack depths are consistently lower than the corresponding 1T C(T) J-resistance curves. The effect of the through-wall crack length upon the J-resistance curve is found to be less significant than that of the surface crack depth. Moreover, the J-resistance curve decreases continuously with increasing surface crack depth.

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.

Finite Element Ductile Crack Growth Simulations of Specimens Under Combined Mechanical and Residual Stresses

2013 ◽  
Author(s):  
Chang-Young Oh ◽  
Jong-Hyun Kim ◽  
Yun-Jae Kim ◽  
P. J. Budden
Keyword(s):  
Residual Stress ◽  
Crack Growth ◽  
Stress Reduction ◽  
Growth Response ◽  
Damage Model ◽  
Stress Distributions ◽  
Ductile Crack ◽  
Size Dependent ◽  
Element Size ◽  
Ductile Crack Growth

This paper provides simulations of ductile crack growth in test specimens using an element-size dependent damage model. The present method used in this paper is based on a stress modified fracture strain damage model with a stress reduction technique. The calibrated damage model is used to predict the load versus ductile crack growth response of test specimens. These tests included some samples that contained self-balancing residual stress distributions. The influence of a residual stress on the load versus crack growth relationship is accurately simulated using the element-size dependent damage model.

Deformation Versus Modified J-Integral Resistance Curves for Ductile Materials

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Xian-Kui Zhu ◽  
Poh-Sang Lam
Keyword(s):  
Deformation Theory ◽  
Size Dependence ◽  
Fracture Property ◽  
J Integral ◽  
Resistance Curve ◽  
Structural Components ◽  
Ductile Materials ◽  
Size Dependent ◽  
Resistance Curves ◽  
Better Than

The J-integral resistance curve (or J-R curve) is an important fracture property of materials and has gained broad applications in assessing the fracture behavior of structural components. Because the J-integral concept was proposed based on the deformation theory of plasticity, the J-R curve is a deformation-based result. It has been known that the J-R curves of a material depend on specimen size and geometry; therefore, a modified J-integral or Jm was proposed to minimize the size dependence. Extensive experiments have shown that the Jm-R curves might remain size-dependent and could not behave better than the traditional deformation J-R curves. To date, however, it is noticed that the Jm-R curves were still used as “size-independent” results in some fracture mechanics analyses. It is necessary to revisit this topic for further clarification. This paper presents a brief review on the development of deformation and modified J-integral testing, and obtains a simple incremental Jm-integral equation. It is followed by typical experimental results with discussions on the issues of constraint or size dependence of J-R and Jm-R curves for different steels and specimens. Finally, a recommendation is made on properly selecting a resistance curve in the fracture analysis.

Element Size Dependent Damage Modeling of Ductile Crack Growth in Circumferential Through-Wall Cracked Pipe Tests

2012 ◽  
Author(s):  
Jong-Hyun Kim ◽  
Nak-Hyun Kim ◽  
Yun-Jae Kim ◽  
Do-Jun Shim
Keyword(s):  
Crack Growth ◽  
Stress Reduction ◽  
Damage Model ◽  
Bending Moment ◽  
Crack Growth Behavior ◽  
Damage Modeling ◽  
Ductile Crack ◽  
Size Dependent ◽  
Element Size ◽  
Ductile Crack Growth

This paper proposes an element-size-dependent damage model to simulate ductile crack growth in full-scale cracked pipes. The proposed method is based on the stress-modified fracture strain damage model modified from stress reduction technique proposed previously by the authors. A modification is made that the critical accumulated damage for progressive cracking is assumed to be dependent on the element size. The proposed method is then compared with a circumferential through-wall cracked pipe test that was conducted during Degrade Piping Program[18]. The bending moment at crack initiation, maximum bending moment, crack extension, and J-integral values were calculated from the FE damage analysis. These results were compared with the experimental results. In addition, results obtained from an existing J-estimation scheme were provided for comparison. All results showed reasonable agreement. The results of the present study demonstrate that the element-size-dependent damage modeling can be applied to simulate the ductile crack growth behavior of a through-wall cracked pipe.

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.

Ductile Failure Simulation of Bending Pipes With Multiple Circumferential Surface Cracks Using an Element-Size Dependent Damage Model

2012 ◽  
Author(s):  
Jong-Hyun Kim ◽  
Nak-Hyun Kim ◽  
Yun-Jae Kim ◽  
Kunio Hasegawa ◽  
Katsumasa Miyazaki
Keyword(s):  
Stress Reduction ◽  
Damage Model ◽  
Ductile Failure ◽  
Bending Moment ◽  
Failure Behavior ◽  
Surface Cracks ◽  
Size Dependent ◽  
Element Size ◽  
Crack Penetration ◽  
Failure Simulation

The purpose of this study is to simulate ductile failure of bending pipes with multiple circumferential surface cracks using an element-size dependent damage model. This method is based on the stress-modified fracture strain damage model with stress reduction technique proposed previously by the authors [9,10]. For validation, simulated results using the proposed method are compared with experimental data of Type 304SS pipes performed by Japanese researchers [19]. To calibrate the proposed method, pipe test data with a single surface crack were compared with simulated results using the damage model. Based on the calibrated damage model, the pipe tests with multiple circumferential surface cracks were simulated. The bending moment at both crack penetration and coalescence were calculated from the FE damage analysis. These results were compared with the experimental results. In spite of its simplicity, the results show that proposed method can simulate ductile failure behavior of bending pipes with multiple circumferential surface cracks.

scholarly journals Analysis of Bifurcation and Chaos of the Size-dependent Micro–plate Considering Damage

2019 ◽  
Vol 8 (1) ◽  
pp. 461-469 ◽  
Author(s):  
Xiumei Wang ◽  
Jihai Yuan ◽  
Haorui Zhai
Keyword(s):  
Internal State ◽  
Couple Stress Theory ◽  
Damage Model ◽  
Modified Couple Stress Theory ◽  
Damage Effect ◽  
Bifurcation And Chaos ◽  
Stress Theory ◽  
Size Dependent ◽  
Material Length Scale ◽  
Plate System

Abstract In this research, nonlinear dynamics and characteristics of a micro–plate system under electrostatic forces on both sides are studied. A novel model, which takes micro-scale effect and damage effect into account, is established on the basis of the Talreja’s tensor valued internal state damage model and modified couple stress theory. According to Hamilton principle, the dynamic governing equations of the size-dependent micro–plate are derived by variational method and solved via Galerkin method and the fourth order Runge-Kutta method. The effects of damage variable and material length scale parameter on bifurcation and chaos of the micro–plate system are presented with numerical simulations using the bifurcation diagram, Poincare map. Results provide a theoretical basis for the design of dynamic stability of electrically actuated micro- structures.

Sign in / Sign up

Export Citation Format

Share Document