Numerical Simulation of Brittle Crack Propagation and Arrest in Steels Considering Shear-Lip Formation

Author(s):  
Shuji Aihara ◽  
Kazuki Shibanuma ◽  
Tetsuya Namegawa
1981 ◽  
Vol 1981 (149) ◽  
pp. 211-218
Author(s):  
Takeshi Kanazawa ◽  
Susumu Machida ◽  
Hiroshi Yajima ◽  
Hajime Kawano

Author(s):  
Satoshi Igi ◽  
Toshihiko Amano ◽  
Takahiro Sakimoto ◽  
Yasuhiro Shinohara ◽  
Tetsuya Tagawa

The drop-weight tear test (DWTT) has been widely used to evaluate the resistance of linepipe steels against brittle fracture propagation. However, in the recent years there is an ambiguity in its evaluation if inverse fracture appears on the specimen fracture surfaces. Although cause of the inverse fracture is not fully understood, compressive pre-straining near the impact hammer and existing tiny split have been discussed as a possible cause. In this paper, machined notch in brittle weld DWTT for X65 was performed and compared with various notch types of DWTTs such as conventional DWTT specimen with a pressed notch (PN), a chevron notch (CN) and a static pre-cracked (SPC). The fracture appearances were compared with different strength X65 - X80 grades linepipes and with different initial notch types. The frequency of the inverse fracture appeared in these DWTTs were different in each material and each specimen types, but there were no cases where the inverse fracture did not occurs. The purpose of DWTT is to evaluate the brittle crack arrestability of the material in a pressurized linepipe. A large scale brittle crack arrest test, so called West Jeferson test is generally used to reproduce crack propagation and arrest behavior in an actual pipeline material. A middle scale test so called Crack Arrest Temperature (CAT) test was also proposed to check the shear area fraction measured in DWTT with API rating with that the local shear lip thickness fraction in those tests. CAT test can well reproduce crack propagation and arrest behavior under the condition of brittle crack initiation from the initial notch.


1996 ◽  
Vol 1996 (179) ◽  
pp. 389-398 ◽  
Author(s):  
Shuji Aihara ◽  
Susumu Machida ◽  
Hitoshi Yoshinari ◽  
Yutaka Tsuchida

Author(s):  
B. Prabel ◽  
S. Marie ◽  
A. Combescure

R&D activities and some development are performed at CEA on the brittle crack propagation and arrest. Phenomena occurring after the initiation of a brittle crack are not yet well understood. Absence of model able to predict the rapid growth of a brittle crack motivates this study. Due to the rapid growth of the crack, inertial effects and dynamic fracture should be considered. Assumption of a linear elastic solid are often preferred, but when plasticity of the material become non negligible (which is the case in the vicinity of the transition zone), these models become more limited. That’s why the paper presented here deals with dynamic crack propagation in elastic-viscoplastic material and aims at proposing a model able to predict the brittle crack propagation and arrest. To this end, experimental work is carried out for different geometries made of french RPV ferritic steel. Compact Tension specimens with different thickness, isothermal rings under compression with different positions of the initial defect to study also a mixed mode configuration. The test conditions and mains results (crack initiation, crack velocity measurements, ...) are collected and presented in a first part of the paper. To model efficiently the crack propagation in the Finite Element calculation, the eXtended Finite Element Method (X-FEM) implemented in the CEA F.E. software CAST3M is described in the second part of the paper. Thanks to this numerical technique, the crack path does not need to follow the element edges and the crack progress is directly incorporated in the degrees of freedom of the elements crossed by the crack. A two-steps methodology is presented in the third and fourth parts of this paper. The first step consider only the CT specimen, experimental crack speed evolution with time is imposed in numerical simulations. Energy terms and stress field at the crack tip are evaluated and discussed to build up a criterion. Then, the criterion identified on CT specimen is used in a second step as a predictive model to simulate crack propagation for each geometry studied (CT, ring in both mode I and mixed mode). In particular, crack propagation models based on the stress field evaluated at the crack tip and on a critical cleavage stress dependent on the strain rate, exhibit very good agreement with experimental data in term of crack speed, crack path and crack length at arrest. The mixed mode case is discussed in detail because to be pertinent, a model of brittle crack propagation should not only give the crack speed, but also its preferred direction of evolution.


2018 ◽  
Vol 13 ◽  
pp. 116-122
Author(s):  
Fuminori Yanagimoto ◽  
Kazuki Shibanuma ◽  
Teppei Okawa ◽  
Katsuyuki Suzuki ◽  
Shuji Aihara

1995 ◽  
Vol 1995 (178) ◽  
pp. 545-554 ◽  
Author(s):  
Shuji Aihara ◽  
Susumu Machida ◽  
Hitoshi Yoshinari ◽  
Hidesato Mabuchi

1992 ◽  
Vol 1992 (172) ◽  
pp. 637-647 ◽  
Author(s):  
Susumu Machida ◽  
Masaaki Matoba ◽  
Hitoshi Yoshinari ◽  
Chikako Tone

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