Two-parameter approach of creep crack initiation times considering the constraint effect induced by specimen geometry

2018 ◽  
Vol 96 ◽  
pp. 31-44 ◽  
Author(s):  
Dongquan Wu ◽  
Hongyang Jing ◽  
Lianyong Xu ◽  
Lei Zhao ◽  
Yongdian Han
Keyword(s):  
Crack Initiation ◽  
Specimen Geometry ◽  
Constraint Effect ◽  
Creep Crack ◽  
Parameter Approach ◽  
Two Parameter

Prediction models of creep crack initiation for different specimen geometry

2018 ◽  
Vol 27 (19) ◽  
pp. 1639-1652 ◽  
Author(s):  
Dongquan Wu ◽  
Hongyang Jing ◽  
Lianyong Xu ◽  
Lei Zhao ◽  
Yongdian Han
Keyword(s):  
Crack Initiation ◽  
Prediction Models ◽  
Specimen Geometry ◽  
Creep Crack

Constraint of Semi-Elliptical Surface Cracks in T and L-Joints

2006 ◽  
Vol 326-328 ◽  
pp. 939-944
Author(s):  
Hyung Yil Lee ◽  
Yun Jae Kim
Keyword(s):  
Finite Element ◽  
Structural Characteristics ◽  
Pressure Vessels ◽  
Surface Cracks ◽  
Spring Model ◽  
Constraint Effect ◽  
T Stress ◽  
Line Spring Model ◽  
Parameter Approach ◽  
Two Parameter

Critical defects in pressure vessels and pipes are generally found in the form of a semielliptical surface crack, and the analysis of which is consequently an important issue in engineering fracture mechanics. Furthermore, in addition to the traditional single parameter K or J-integral, the second parameter like T-stress should be measured to quantify the constraint effect. In this work, the validity of the line-spring model is investigated by comparing line-spring J-T solutions to the reference 3D finite element J-T solutions. A full 3D-mesh generating program for semi-elliptical surface cracks is employed to provide such reference 3D solutions. Then some structural characteristics of the surface-cracked T and L-joints are studied by mixed mode line-spring finite element. Negative T-stresses observed in T and L-joints indicate the necessity of J-T two parameter approach for analyses of surface-cracked T and L-joints.

Correlation Analysis Between Time-Dependent Creep Crack-Tip Stress and Constraint Effect on Creep Crack Initiation Time

2020 ◽  
Author(s):  
Seung-Ho Lee ◽  
Hyun-Woo Jung ◽  
Yun-Jae Kim ◽  
Kamran Nikbin ◽  
Robert A. Ainsworth
Keyword(s):  
Crack Initiation ◽  
Correlation Analysis ◽  
Creep Crack Growth ◽  
Crack Tip ◽  
Compact Tension ◽  
Time Dependent ◽  
Initiation Time ◽  
Constraint Effect ◽  
Creep Crack ◽  
Crack Tip Stress

Abstract In this study, to qualify the constraint effect on creep crack initiation, the correlation analysis between proposed constraint parameter Q’ using time-dependent creep crack-tip stress and creep crack initiation time variable Ai was performed. Ai implies the influence of constraint effect on creep crack initiation. The procedure to calculate the Ai and the Q’-parameter was presented. To evaluate various status of constraint effect, creep crack growth tests for twenty-one compact tension specimens of Type 316H stainless steel at 550°C were investigated. The results of correlation analysis explain the reason for the different initiation time at the same C* level in respect of constraint effect.

Investigation on creep crack initiation prediction considering constraint effect using constraint parameter Q

2018 ◽  
Vol 96 ◽  
pp. 631-641 ◽  
Author(s):  
Dongquan Wu ◽  
Hongyang Jing ◽  
Lianyong Xu ◽  
Lei Zhao ◽  
Yongdian Han
Keyword(s):  
Crack Initiation ◽  
Constraint Effect ◽  
Creep Crack
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