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262 results on '"Shi, Hui‐Ji"'

15. Secondary orientation effects on the low cycle fatigue behaviors of rectangular‐sectional Ni‐based single crystal superalloys at medium and high temperatures.

Author

Rui, Shao‐Shi, He, Zhiwu, Guo, Yiyun, Su, Yue, Han, Qi‐Nan, Ma, Xianfeng, and Shi, Hui‐Ji

Subjects
ALLOY fatigue, SINGLE crystals, HEAT resistant alloys, HIGH temperatures, TURBINE blades, HIGH cycle fatigue, FATIGUE life, STRESS relaxation (Mechanics)
Abstract

Turbine blades made of Ni‐based single crystal superalloys (NBSXs) have long‐strip shaped cross sections and rectangular‐sectional structures, where the secondary orientation produces potential effects even the primary orientation is fixed at [001]. Low cycle fatigue behaviors between [010] and [110] transversely oriented rectangular‐sectional NBSX specimens were compared. Obvious differences existed under 600°C but disappeared under 850°C, with the deformation mechanism and fracture mode transitions. Secondary orientation effects on stress asymmetry and fatigue life cannot be described by the conventional LCP model and critical plane method but were well explained by dislocation path length‐dependent back‐stress model and A.N. May's random slip model. Highlights: Secondary orientation effects on rectangular‐sectional NBSXs under 600°C are more obvious than those under 850°C;[110] case shows higher stress asymmetry and longer fatigue life than [010] case under 600°C;The secondary orientation effect on stress asymmetry is attributed to the different dislocations paths;The secondary orientation effect on fatigue life is attributed to the different dislocations intrusions' depths. [ABSTRACT FROM AUTHOR]

Published
2023
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46. Experimental and FEA investigations on the fracture properties of pipe structures under internal pressure in DBTT region

Author

Wang, Zhao-Xi, Xue, Fei, Shi, Hui-Ji, and Lu, Jian

Subjects
Pipe lines -- Mechanical properties, Pipe lines -- Thermal properties, Pipe lines -- Testing, Pressure -- Research, Finite element method -- Research, Engineering and manufacturing industries
Abstract

The fracture behavior of pipes with penetrating cracks was experimentally investigated with the results of the load-deflection curves and crack length. J-R curves were obtained from the testing results for different temperatures. With the decrement in temperature, the critical J integral decreases and the tearing modulus increases. An updated continuum damage model was proposed, in which the fracture energy density as a function of the stress triaxiality, temperature and strain rate in the transition region was taken as the critical damage factor. The uni-axial tension experiments at different temperatures were carried out to obtain the basic material properties and the critical fracture energy density, to verify the validity of the damage model. Based on detailed finite element analyses with the proposed updated continuum damage model, the loading level of pipes with penetrating cracks was estimated and compared with the experimental results, meanwhile the fracture processes of the pipeline structure in the ductile-brittle-transition-temperature region were reproduced. It has been shown that the fracture process in the transition region strongly depends on both the stress and strain state, and can be effectively predicted using the continuum damage models incorporating with the stress state effect. [DOI: 10.1115/1.3110015] Keywords: continuum damage model, transition temperature region, fracture energy density, stress triaxiality

Published
2009

49. Fracture mode identification of low alloy steels and cast irons by electron back-scattered diffraction misorientation analysis

Author

Chuman Yasuharu, Qiu Wenhui, Shang Yi-Bo, Rui Shao-Shi, Niu Li-sha, Matsumoto Shunsaku, and Shi Hui-ji

Subjects
010302 applied physics, Diffraction, Toughness, Materials science, Polymers and Plastics, Misorientation, Mechanical Engineering, Metallurgy, Metals and Alloys, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Mechanics of Materials, Tension (geology), 0103 physical sciences, Ultimate tensile strength, Materials Chemistry, Ceramics and Composites, Fracture (geology), Composite material, 0210 nano-technology, Striation, Electron backscatter diffraction
Abstract

The fracture modes of low alloy steels and cast irons under tensile and fatigue conditions were identified by electron back-scattered diffraction (EBSD) misorientation analysis in this research. The curves of grain reference orientation deviation (GROD) distribution perpendicular to the fracture surface were obtained by EBSD observation, and the characteristics of each fracture mode were identified. The GROD value of the specimen fractured in tension decreases to a constant related to the elongation of corresponding specimen in the far field (farther than 5 mm away from the fracture surface). The peak exhibits in GROD curves of two smooth specimens and a notched specimen near the fracture surface (within 5 mm away from the fracture surface), and the formation mechanisms were discussed in detail based on the influences of specimen geometries (smooth or notched) and material toughness. The GROD value of fatigue fractured specimen is close to that at undeformed condition in the whole field, except the small area near the crack path. The loading conditions (constant stress amplitude loading or constant stress intensity factor range △ K loading) and the EBSD striation formation during fatigue crack propagation were also studied by EBSD observation parallel to the crack path.

Published
2017

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