Proposal of New Combination Criterion for Pipe With Circumferential Multiple Cracks Based on Ductile Failure Simulation

2018 ◽  
Author(s):  
Myeong-Woo Lee ◽  
Kunio Hasegawa ◽  
Yun-Jae Kim
Keyword(s):  
Ductile Failure ◽  
Numerical Data ◽  
New Combination ◽  
Multiple Cracks ◽  
Damage Analysis ◽  
Fracture Test ◽  
Combination Rule ◽  
Failure Simulation ◽  
Bending Stresses ◽  
Strain Model

In this paper, the combination rule for circumferential multiple-cracked pipe assessment is investigated using finite element damage analysis. The FE damage analysis based on the stress-modified fracture strain model is validated against limited fracture test data of two circumferential surface cracked pipes. Then systematic parametric study is performed using FE damage analysis for symmetrical surface cracked pipes. Failure bending stresses are calculated using the combination rule and the net-section collapse load approach for single crack provided in ASME BPV Code. It is found that predicted failure bending stress using the combination rule might be non-conservative when the distance between two cracks is short. To overcome the problem, a new combination criterion based on crack dimensions is proposed and compared with numerical data.

Numerical Study on Longitudinal Distance Effect on Failure Stress of Non-Aligned Twin Cracked Pipe

2018 ◽  
Author(s):  
Thanh-Long Nguyen ◽  
Myeong-Woo Lee ◽  
Kunio Hasegawa ◽  
Yun-Jae Kim
Keyword(s):  
Fracture Strain ◽  
Numerical Study ◽  
Distance Effect ◽  
Failure Stress ◽  
Axial Distance ◽  
Damage Analysis ◽  
Asme Code ◽  
Bending Stresses ◽  
Strain Model ◽  
Longitudinal Distance

In this study, the effect of longitudinal distance H between non-aligned twin cracks is investigated using finite element damage analysis. The FE damage analysis based on the stress-modified fracture strain model is used to calculate the failure stress of non-aligned twin cracked pipe. Parametric study on the axial distance H between non-aligned twin cracks with various crack depths and lengths were conducted and compared with predictions using the alignment rules and the net-section collapse load approach for single crack provided in ASME Code. It is shown that the trend of the predicted collapse bending stresses for the non-aligned twin cracked pipes using FE damage analysis are different from the ones using the alignment rule.

A finite element ductile failure simulation method using stress-modified fracture strain model

2011 ◽  
Vol 78 (1) ◽  
pp. 124-137 ◽  
Author(s):  
Chang-Sik Oh ◽  
Nak-Hyun Kim ◽  
Yun-Jae Kim ◽  
Jong-Hyun Baek ◽  
Young-Pyo Kim ◽  
...  
Keyword(s):  
Finite Element ◽  
Fracture Strain ◽  
Ductile Failure ◽  
Simulation Method ◽  
Failure Simulation ◽  
Strain Model

Applicability of Net-Section Collapse Load Approach to Multiple-Cracked Pipe Assessment: Numerical Study

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Myeong-Woo Lee ◽  
So-Dam Lee ◽  
Yun-Jae Kim
Keyword(s):  
Finite Element ◽  
Test Data ◽  
Parametric Study ◽  
Fracture Strain ◽  
Numerical Study ◽  
Damage Analysis ◽  
Collapse Load ◽  
Fracture Test ◽  
Strain Model

In this paper, applicability of net-section collapse load approach to circumferential multiple-cracked pipe assessment is investigated using finite element (FE) damage analysis. The FE damage analysis based on the stress-modified fracture strain model is validated against limited fracture test data of two circumferential surface-cracked pipes. Then, the systematic parametric study is performed using the FE damage analysis for symmetrical and asymmetrical surface-cracked pipes. It is found that predictions using the net-section collapse load approach tend to be more accurate with increasing the distance between two symmetrical cracks. For asymmetrical cracks, it is found that the deeper crack plays a more important role and that the existing net-section collapse load expression can be potentially nonconservative. Idealization to symmetrical cracks based on the deeper crack is proposed.

A Non-Monotone Line Search Combination Technique for Unconstrained Optimization

2014 ◽  
Vol 8 (1) ◽  
pp. 218-221 ◽  
Author(s):  
Ping Hu ◽  
Zong-yao Wang
Keyword(s):  
Global Convergence ◽  
Unconstrained Optimization ◽  
Numerical Experiments ◽  
Line Search ◽  
Optimization Problems ◽  
Search Algorithm ◽  
New Combination ◽  
Combination Rule ◽  
Combination Technique ◽  
Unconstrained Optimization Problems

We propose a non-monotone line search combination rule for unconstrained optimization problems, the corresponding non-monotone search algorithm is established and its global convergence can be proved. Finally, we use some numerical experiments to illustrate the new combination of non-monotone search algorithm’s effectiveness.

Ductile Failure Simulation of Tensile Plates With Multiple Through-Wall Cracks

2009 ◽  
Author(s):  
Nak-Hyun Kim ◽  
Yun-Jae Kim ◽  
Chang-Sik Oh
Keyword(s):  
Experimental Data ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Numerical Method ◽  
Ductile Failure ◽  
Crack Coalescence ◽  
Element Analysis ◽  
Failure Simulation ◽  
Damage Theory

This paper proposes a simple numerical method to simulate plastic behaviours of tensile plates with twin through-wall cracks. The method is based on finite element analysis with a simple damage theory. To validate the proposed method, simulated results are compared with experimental data performed by Japanese researchers. Despite its simplicity, the proposed method well predicts plastic behaviours of tensile plates with twin cracks, including crack coalescence. Predicted maximum loads are overall lower than experimentally-measured ones.

A New Combination Rule Based on the Average Belief Function

2018 ◽  
Author(s):  
Gabriel Awogbami ◽  
Norbert Agana ◽  
Shabnam Nazmi ◽  
Abdollah Homaifar
Keyword(s):  
Belief Function ◽  
New Combination ◽  
Combination Rule ◽  
Rule Based
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