TY - GEN
T1 - Prediction of CTOD based on GE/EPRI for pipes with a semi-elliptical surface crack under global bending
AU - Jang, Youn Young
AU - Huh, Nam Su
AU - Lee, Jae Bin
AU - Kim, Ki Seok
AU - Cho, Woo Yeon
N1 - Publisher Copyright:
Copyright © 2017 by the International Society of Offshore and Polar Engineers (ISOPE).
PY - 2017
Y1 - 2017
N2 - For many structural components in oil and gas transmission pipelines, fracture assessment is one of essential elements for structural integrity since a common failure arises from internal cracks mostly formed during installation or operation in severe environment. In the fracture assessment for pipeline, the fracture mechanics parameters. i.e., Jintegral and crack-tip opening displacement (CTOD), have been used, in which these parameters can characterize crack initiation and instability well. In particular, CTOD is widely used for fracture assessment in strain-based design (SBD) concept as well as the transportation pipelines or submarine riser industries subject to large deformation. Many researches have been made to estimate fracture parameters, and several engineering approaches such as General Electric/Electric Power Research Institute (GE/EPRI) and reference stress (RS) method have been suggested. Among them, a GE/EPRI method is one of general estimation approaches based on finite element (FE) analysis, where material behavior is assumed to be characterized by the Ramberg-Osgood (R-O) relation. In GE/EPRI approach, plastic influence functions used to calculate fully plastic term of fracture parameter are calibrated through the detailed FE analyses according to geometries and material properties, respectively. In this context, FE analyses should be systematically performed to estimate CTOD for various cracked pipes based on GE/EPRI method. In the present paper, 3-dimensional (3-D) elastic-plastic FE analyses were carried out to calibrate and propose the fully plastic solutions of CTOD based on GE/EPRI concept for pipes with a semi-elliptical surface crack. The geometric and material variables of a cracked pipe such as pipe thickness, crack length and strain hardening exponent were systematically varied to cover practical ranges of these values. In terms of loading condition, pure bending moment which is most important loading mode in pipeline was considered.
AB - For many structural components in oil and gas transmission pipelines, fracture assessment is one of essential elements for structural integrity since a common failure arises from internal cracks mostly formed during installation or operation in severe environment. In the fracture assessment for pipeline, the fracture mechanics parameters. i.e., Jintegral and crack-tip opening displacement (CTOD), have been used, in which these parameters can characterize crack initiation and instability well. In particular, CTOD is widely used for fracture assessment in strain-based design (SBD) concept as well as the transportation pipelines or submarine riser industries subject to large deformation. Many researches have been made to estimate fracture parameters, and several engineering approaches such as General Electric/Electric Power Research Institute (GE/EPRI) and reference stress (RS) method have been suggested. Among them, a GE/EPRI method is one of general estimation approaches based on finite element (FE) analysis, where material behavior is assumed to be characterized by the Ramberg-Osgood (R-O) relation. In GE/EPRI approach, plastic influence functions used to calculate fully plastic term of fracture parameter are calibrated through the detailed FE analyses according to geometries and material properties, respectively. In this context, FE analyses should be systematically performed to estimate CTOD for various cracked pipes based on GE/EPRI method. In the present paper, 3-dimensional (3-D) elastic-plastic FE analyses were carried out to calibrate and propose the fully plastic solutions of CTOD based on GE/EPRI concept for pipes with a semi-elliptical surface crack. The geometric and material variables of a cracked pipe such as pipe thickness, crack length and strain hardening exponent were systematically varied to cover practical ranges of these values. In terms of loading condition, pure bending moment which is most important loading mode in pipeline was considered.
KW - Bending moment
KW - Crack-tip opening displacement
KW - Elastic plastic facture mechanics
KW - GE/EPRI
KW - Pipeline
KW - Plastic influence function
KW - Semi-elliptical surface crack
UR - http://www.scopus.com/inward/record.url?scp=85038941045&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:85038941045
T3 - Proceedings of the International Offshore and Polar Engineering Conference
SP - 256
EP - 260
BT - Proceedings of the 27th International Ocean and Polar Engineering Conference, ISOPE 2017
PB - Society of Petroleum Engineers
T2 - 27th International Ocean and Polar Engineering Conference, ISOPE 2017
Y2 - 25 June 2017 through 30 June 2017
ER -