The Experts below are selected from a list of 116829 Experts worldwide ranked by ideXlab platform
A G Kostyuk - One of the best experts on this subject based on the ideXlab platform.
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long Term Strength of steam turbine rotors in the stress concentration zone
Thermal Engineering, 2006Co-Authors: A G KostyukAbstract:The results from calculating the long-Term Strength of single-piece forged rotors using the natural mechanistic procedure [1] are compared with the experimental long-Term Strength characteristics of the models of high-temperature disk rims [2, 3] and with the field data on failures of such rims [4]. A new experimentally substantiated calculation procedure is proposed. The use of the procedure for estimating the long-Term Strength of the rotors of turbines now in service shows that the failure probability of the rotor rims of 800 MW turbines that have been in service for 100 000 h is approximately equal to 30%.
Katsuhiko Kaneko - One of the best experts on this subject based on the ideXlab platform.
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Estimation of Long-Term Strength of Rock Based on Subcritical Crack Growth
Engineering Geology for Society and Territory - Volume 2, 2015Co-Authors: Yoshitaka Nara, Sumihiko Murata, Tsuyoshi Ishida, Katsuhiko KanekoAbstract:In this study, based on information about subcritical crack growth, the long-Term Strength of rock was estimated with consideration of changes in environmental conditions. The long-Term Strength of granite is known to be lower in water than in air. From the estimation of the long-Term Strength for the situation where the surrounding environment changes from air to water, it was revealed that when the environmental condition was changed from air to water, the long-Term Strength converged to that of rock continuously in water, even when a dry condition (where rock was kept in air) had been maintained for a long time (1 or 100 years). The results of long-Term Strength estimation indicate that the acceleration of crack growth in water strongly influences the estimated long-Term Strength of granite. It is therefore concluded that water has a significant influence on the long-Term stability of rock mass structures such as rock slopes.
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Subcritical crack growth and long-Term Strength in rock and cementitious material
International Journal of Fracture, 2010Co-Authors: Yoshitaka Nara, Masafumi Takada, Daisuke Mori, Hitoshi Owada, Tetsuro Yoneda, Katsuhiko KanekoAbstract:High-Strength and ultra low-permeability concrete (HSULPC) is a strong candidate for a radioactive waste package containing transuranic radionuclides (TRU waste) for geological disposal. Knowledge of the time-dependent fracturing of HSULPC and surrounding rock mass is essential to assess the long-Term stability of such underground repositories. We have measured crack velocity in andesite and HSULPC both in air and water to examine subcritical crack growth by the Double-Torsion method. In air, the crack velocity in andesite increased when the temperature and relative humidity increased. On the other hand, the temperature and relative humidity had little effect on the crack velocity in HSULPC in air. In water, the crack velocity increased when the temperature was higher for both andesite and HSULPC. Using these experimental results, the long-Term Strength was estimated. It was shown that the long-Term Strength of HSULPC was higher than that of andesite. In air, the long-Term Strength for andesite was affected by the temperature and relative humidity. The long-Term Strength for andesite decreased when the temperature or relative humidity increased. For HSULPC, the change of the long-Term Strength with varying temperature or relative humidity was smaller than andesite in air. In water, the long-Term Strength for both materials decreased with increasing the temperature. Comparing the long-Term Strength of andesite and HSULPC at the same environmental conditions, it was recognized that the decrease of the long-Term Strength of HSULPC is smaller than that of andesite. The long-Term Strength in water was smaller than that in air for both materials.
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Effect of Water on Subcritical Crack Growth Index and Long-Term Strength for Rock
72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010, 2010Co-Authors: Yoshitaka Nara, Tetsuro Yoneda, Toshifumi Igarashi, Naoki Hiroyoshi, Katsuhiko KanekoAbstract:Long-Term stability is required for the structures in a rock mass. Especially, the estimation of long-Term Strength of rock is essential to consider the long-Term stability. In this study, we investigated the time-dependent crack growth in rock. Specifically, subcritical crack growth in water and in air with different relative humidities was measured in order to investigate the effect of water on the value of subcritical crack growth index and the long-Term Strength for rock. It was shown that subcritical crack growth index in water was smaller than that in air. Additionally, subcritical crack growth index tended to be smaller when the relative humidity was higher. The long-Term Strength in water was smaller than that in air. In air, the long-Term Strength tended to be smaller when the relative humidity was higher. The long-Term Strength is larger when subcritical crack growth index is larger. For the long-Term stability, it is thus important to achieve a condition where subcritical crack growth index becomes larger. It is concluded that retarding the migration of water into and through rock and keeping low humidity is important.
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Effect of Surrounding Environment on Subcritical Crack Growth Index and Long-Term Strength for Rock
Journal of the Society of Materials Science Japan, 2010Co-Authors: Yoshitaka Nara, Tetsuro Yoneda, Toshifumi Igarashi, Naoki Hiroyoshi, Katsuhiko KanekoAbstract:Study of subcritical crack growth is important in estimating the long-Term Strength of rock and in ensuring the long-Term stability of structures in a rock mass. The long-Term Strength is affected by the value of subcritical crack growth index (SCGI). However, the effect of environmental conditions on SCGI has not been clarified. In this study, we have estimated SCGI under various environmental conditions on a sample of Kumamoto andesite, using the Double-Torsion method. We show that the SCGI decreased when the temperature is higher in both air and water; the SCGI in water is smaller than that in air. When the relative humidity of the air increased, SCGI tended to be smaller and at 90 % relative humidity was close to the value in water. Under alkali conditions, the SCGI decreased slightly. Using the values of SCGI, the long-Term Strength was estimated and it is shown that the long-Term Strength decreased when SCGI was smaller. It is concluded that SCGI and the long-Term Strength is affected by the surrounding environment, specifically by the temperature and water. To ensure the long-Term stability of rock, the control of the temperature and water migration is important.
Ch. G. Mustafin - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the long-Term Strength of elements of steam turbine rotors
Thermal Engineering, 1998Co-Authors: Ch. G. MustafinAbstract:The results of an experimental study of the long-Term Strength of flat models of the rims of steam turbine disks at a temperature of 540°C are presented; the models were made of steel 25Kh1M1F (R2M). A comparison of these results with an analytical evaluation of the long-Term Strength of the models was made.
Yoshitaka Nara - One of the best experts on this subject based on the ideXlab platform.
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Estimation of Long-Term Strength of Rock Based on Subcritical Crack Growth
Engineering Geology for Society and Territory - Volume 2, 2015Co-Authors: Yoshitaka Nara, Sumihiko Murata, Tsuyoshi Ishida, Katsuhiko KanekoAbstract:In this study, based on information about subcritical crack growth, the long-Term Strength of rock was estimated with consideration of changes in environmental conditions. The long-Term Strength of granite is known to be lower in water than in air. From the estimation of the long-Term Strength for the situation where the surrounding environment changes from air to water, it was revealed that when the environmental condition was changed from air to water, the long-Term Strength converged to that of rock continuously in water, even when a dry condition (where rock was kept in air) had been maintained for a long time (1 or 100 years). The results of long-Term Strength estimation indicate that the acceleration of crack growth in water strongly influences the estimated long-Term Strength of granite. It is therefore concluded that water has a significant influence on the long-Term stability of rock mass structures such as rock slopes.
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Subcritical crack growth and long-Term Strength in rock and cementitious material
International Journal of Fracture, 2010Co-Authors: Yoshitaka Nara, Masafumi Takada, Daisuke Mori, Hitoshi Owada, Tetsuro Yoneda, Katsuhiko KanekoAbstract:High-Strength and ultra low-permeability concrete (HSULPC) is a strong candidate for a radioactive waste package containing transuranic radionuclides (TRU waste) for geological disposal. Knowledge of the time-dependent fracturing of HSULPC and surrounding rock mass is essential to assess the long-Term stability of such underground repositories. We have measured crack velocity in andesite and HSULPC both in air and water to examine subcritical crack growth by the Double-Torsion method. In air, the crack velocity in andesite increased when the temperature and relative humidity increased. On the other hand, the temperature and relative humidity had little effect on the crack velocity in HSULPC in air. In water, the crack velocity increased when the temperature was higher for both andesite and HSULPC. Using these experimental results, the long-Term Strength was estimated. It was shown that the long-Term Strength of HSULPC was higher than that of andesite. In air, the long-Term Strength for andesite was affected by the temperature and relative humidity. The long-Term Strength for andesite decreased when the temperature or relative humidity increased. For HSULPC, the change of the long-Term Strength with varying temperature or relative humidity was smaller than andesite in air. In water, the long-Term Strength for both materials decreased with increasing the temperature. Comparing the long-Term Strength of andesite and HSULPC at the same environmental conditions, it was recognized that the decrease of the long-Term Strength of HSULPC is smaller than that of andesite. The long-Term Strength in water was smaller than that in air for both materials.
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Effect of Water on Subcritical Crack Growth Index and Long-Term Strength for Rock
72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010, 2010Co-Authors: Yoshitaka Nara, Tetsuro Yoneda, Toshifumi Igarashi, Naoki Hiroyoshi, Katsuhiko KanekoAbstract:Long-Term stability is required for the structures in a rock mass. Especially, the estimation of long-Term Strength of rock is essential to consider the long-Term stability. In this study, we investigated the time-dependent crack growth in rock. Specifically, subcritical crack growth in water and in air with different relative humidities was measured in order to investigate the effect of water on the value of subcritical crack growth index and the long-Term Strength for rock. It was shown that subcritical crack growth index in water was smaller than that in air. Additionally, subcritical crack growth index tended to be smaller when the relative humidity was higher. The long-Term Strength in water was smaller than that in air. In air, the long-Term Strength tended to be smaller when the relative humidity was higher. The long-Term Strength is larger when subcritical crack growth index is larger. For the long-Term stability, it is thus important to achieve a condition where subcritical crack growth index becomes larger. It is concluded that retarding the migration of water into and through rock and keeping low humidity is important.
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Effect of Surrounding Environment on Subcritical Crack Growth Index and Long-Term Strength for Rock
Journal of the Society of Materials Science Japan, 2010Co-Authors: Yoshitaka Nara, Tetsuro Yoneda, Toshifumi Igarashi, Naoki Hiroyoshi, Katsuhiko KanekoAbstract:Study of subcritical crack growth is important in estimating the long-Term Strength of rock and in ensuring the long-Term stability of structures in a rock mass. The long-Term Strength is affected by the value of subcritical crack growth index (SCGI). However, the effect of environmental conditions on SCGI has not been clarified. In this study, we have estimated SCGI under various environmental conditions on a sample of Kumamoto andesite, using the Double-Torsion method. We show that the SCGI decreased when the temperature is higher in both air and water; the SCGI in water is smaller than that in air. When the relative humidity of the air increased, SCGI tended to be smaller and at 90 % relative humidity was close to the value in water. Under alkali conditions, the SCGI decreased slightly. Using the values of SCGI, the long-Term Strength was estimated and it is shown that the long-Term Strength decreased when SCGI was smaller. It is concluded that SCGI and the long-Term Strength is affected by the surrounding environment, specifically by the temperature and water. To ensure the long-Term stability of rock, the control of the temperature and water migration is important.
Zhou Zhiwei - One of the best experts on this subject based on the ideXlab platform.
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Discussion on DeTermination Method of Long-Term Strength of Rock Salt
Energies, 2020Co-Authors: Ding Guosheng, Jianfeng Liu, Lu Wang, Wu Zhide, Zhou ZhiweiAbstract:Due to the extremely low permeability and the excellent creep behavior, rock salt is the optimal surrounding rock of underground energy storage. The long-Term safe operation of the rock salt energy storage is closely related to the creep behavior and long-Term Strength of rock salt, but few researches focus on the long-Term Strength of rock salt. In order to more accurately predict the long-Term Strength of rock salt, the isochronous stress–strain curve method and the volume expansion method for deTermining the long-Term Strength were analyzed and discussed based on axial compression tests and axial creep tests. The results show that the isochronous stress–strain curve method is intuitive but will greatly increase the test cost and test time to obtain a satisfactory result. The volume expansion method is simple, but the long-Term Strength obtained according to the inflection point of volumetric strain is much greater than the actual long-Term Strength of rock salt. Therefore, a new method applicable to rock salt was proposed based on the evolution of damage in rock salt in this paper, which takes the corresponding stress value at the damage initiation point as the long-Term Strength. The long-Term Strength deTermined by this method is consistent with that by the isochronous stress–strain curve method. The method is more economical and convenient and aims to provide a reference for the long-Term stability study of underground salt caverns.
