The Experts below are selected from a list of 68991 Experts worldwide ranked by ideXlab platform
Wu Yang - One of the best experts on this subject based on the ideXlab platform.
-
effect of Cyclic Loading on cracking behaviour of x 70 pipeline steel in near neutral ph solutions
Journal of Materials Science & Technology, 2009Co-Authors: L I Guangfu, Ruipeng Yang, Wu YangAbstract:The cracking behaviour of X-70 pipeline steel in near-neutral pH solutions was studied under different modes of Cyclic Loading. The crack propagation process of X-70 pipeline steel under low frequency Cyclic Loading condition was controlled mainly by stress corrosion cracking (SCC) mechanism. Under mixed-mode Cyclic Loading, both higher tensile stress and shear stress made cracks easier to propagate. Applied cathodic potentials and high content of carbon dioxide in solutions also promoted the propagation of cracks. The propagation directions of cracks were different under different Cyclic Loading conditions. Under mode I (pure tensile stress) Cyclic Loading condition, cracks were straight and perpendicular to the tensile stress axis, while under mixed-mode I/Ill (tensile/shear stress) Cyclic Loading, cracks were sinuous and did not propagate in the direction perpendicular to the main tensile stress axis. Under the mixed-mode Cyclic Loading, cracks were much easier to propagate, suggesting that shear stress intensified the role of tensile stress. In addition, shear stress promoted the interaction between cracks, resulting in easier coalescence of cracks.
-
effect of Cyclic Loading on crack propagation of x 70 pipeline steel in near neutral ph solution
Key Engineering Materials, 2005Co-Authors: Guang Fu Li, Wu YangAbstract:Crack propagation of X-70 pipeline steel in near-neutral pH solution was studied under different modes of Cyclic Loading. A revised equation of crack growth rate vs. Δ K was obtained. Average crack growth rate increased with cycles under conditions of different R values. Linear shape notch specimen made cracks much easier to initiate and propagate than V-shaped notch specimen did. For different R values, the curves of crack growth rate with cycles were similar, but the platform propagation period and quick propagation period were different obviously. Crack growth rate at both periods increased and thus failure time decreased markedly with decrease of R value. The propagation directions of cracks were different under different Cyclic Loading conditions. Under mode I (single tensile stress) Cyclic Loading, cracks were straight and perpendicular to the tensile stress axis, while under mixed-mode I/III (tensile/shear stress) Cyclic Loading, cracks were sinuous and did not propagate in the direction perpendicular to the main tensile stress axis.
Jianfeng Liu - One of the best experts on this subject based on the ideXlab platform.
-
damage evolution of rock salt under Cyclic Loading in unixial tests
Acta Geotechnica, 2014Co-Authors: Jianfeng Liu, Heping Xie, Zhengmeng Hou, Chunhe Yang, Liang ChenAbstract:Cyclic Loading tests of rock salt were performed to investigate the characteristics of damage evolution of the surrounding rock in gas caverns. In this experiment, the Cyclic Loading process was carried out on seven stress levels from 20 to 86 % of the uniaxial compressive strength. The sine wave with a frequency of 1 Hz was adopted in the Cyclic Loading test. Experimental results show that at the first stress level, the damage evolution is rather limited or negligible under Cyclic Loading, which is controlled within the elastic limit. With the increase in stress level, the damage evolution becomes more evident. An increasing tendency of damage variable can be observed if the stress level surpasses 40 % of the uniaxial compressive strength. A maximum damage value of around 0.95 is recorded when the stress level is over 85 % of the uniaxial strength. In this paper, a damage evolution equation is also introduced and good agreement is obtained with the experimental data. Based on the experimental data, it is shown that the design practice of gas cavern concerning the degree of strength utilization of the surrounding rock is rather conservative considering the reducing effect of the minimal gas pressure on the damage evolution.
Shengqi Yang - One of the best experts on this subject based on the ideXlab platform.
-
experimental investigation on mechanical damage characteristics of sandstone under triaxial Cyclic Loading
Geophysical Journal International, 2015Co-Authors: Shengqi Yang, P G Ranjith, Yanhua Huang, Peng Fei Yin, Hongwen Jing, Yilin GuiAbstract:The mechanical damage characteristics of sandstone subjected to Cyclic Loading is very significant to evaluate the stability and safety of deep excavation damage zones. However to date, there are very few triaxial experimental studies of sandstone under Cyclic Loading. Moreover, few X-ray micro-computed tomography (micro-CT) observations have been adopted to reveal the damage mechanism of sandstone under triaxial Cyclic Loading. Therefore, in this research, a series of triaxial Cyclic Loading tests and X-ray micro-CT observations were conducted to analyse the mechanical damage characteristics of sandstone with respect to different confining pressures. The results indicated that at lower confining pressures, the triaxial strength of sandstone specimens under Cyclic Loading is higher than that under monotonic Loading; whereas at confining pressures above 20 MPa, the triaxial strength of sandstone under Cyclic Loading is approximately equal to that under monotonic Loading. With the increase of cycle number, the crack damage threshold of sandstone first increases, and then significantly decreases and finally remains constant. Based on the damage evolution of irreversible deformation, it appears that the axial damage value of sandstone is all higher than the radial damage value before the peak strength; whereas the radial damage value is higher than the axial damage value after the peak strength. The evolution of Young's modulus and Poisson's ratio of sandstone can be characterized as having four stages: (i) Stage I: material strengthening; (ii) Stage II: material degradation; (iii) Stage III: material failure and (iv) Stage IV: structure slippage. X-ray micro-CT observations demonstrated that the CT scanning surface images of sandstone specimens are consistent with actual surface crack photographs. The analysis of the cross-sections of sandstone supports that the system of crack planes under triaxial Cyclic Loading is much more complicated than that under triaxial monotonic Loading. More axial and lateral tensile cracks were observed in the specimens under Cyclic Loading than under monotonic Loading.
Liang Chen - One of the best experts on this subject based on the ideXlab platform.
-
damage evolution of rock salt under Cyclic Loading in unixial tests
Acta Geotechnica, 2014Co-Authors: Jianfeng Liu, Heping Xie, Zhengmeng Hou, Chunhe Yang, Liang ChenAbstract:Cyclic Loading tests of rock salt were performed to investigate the characteristics of damage evolution of the surrounding rock in gas caverns. In this experiment, the Cyclic Loading process was carried out on seven stress levels from 20 to 86 % of the uniaxial compressive strength. The sine wave with a frequency of 1 Hz was adopted in the Cyclic Loading test. Experimental results show that at the first stress level, the damage evolution is rather limited or negligible under Cyclic Loading, which is controlled within the elastic limit. With the increase in stress level, the damage evolution becomes more evident. An increasing tendency of damage variable can be observed if the stress level surpasses 40 % of the uniaxial compressive strength. A maximum damage value of around 0.95 is recorded when the stress level is over 85 % of the uniaxial strength. In this paper, a damage evolution equation is also introduced and good agreement is obtained with the experimental data. Based on the experimental data, it is shown that the design practice of gas cavern concerning the degree of strength utilization of the surrounding rock is rather conservative considering the reducing effect of the minimal gas pressure on the damage evolution.
L I Guangfu - One of the best experts on this subject based on the ideXlab platform.
-
effect of Cyclic Loading on cracking behaviour of x 70 pipeline steel in near neutral ph solutions
Journal of Materials Science & Technology, 2009Co-Authors: L I Guangfu, Ruipeng Yang, Wu YangAbstract:The cracking behaviour of X-70 pipeline steel in near-neutral pH solutions was studied under different modes of Cyclic Loading. The crack propagation process of X-70 pipeline steel under low frequency Cyclic Loading condition was controlled mainly by stress corrosion cracking (SCC) mechanism. Under mixed-mode Cyclic Loading, both higher tensile stress and shear stress made cracks easier to propagate. Applied cathodic potentials and high content of carbon dioxide in solutions also promoted the propagation of cracks. The propagation directions of cracks were different under different Cyclic Loading conditions. Under mode I (pure tensile stress) Cyclic Loading condition, cracks were straight and perpendicular to the tensile stress axis, while under mixed-mode I/Ill (tensile/shear stress) Cyclic Loading, cracks were sinuous and did not propagate in the direction perpendicular to the main tensile stress axis. Under the mixed-mode Cyclic Loading, cracks were much easier to propagate, suggesting that shear stress intensified the role of tensile stress. In addition, shear stress promoted the interaction between cracks, resulting in easier coalescence of cracks.
