The Experts below are selected from a list of 3816 Experts worldwide ranked by ideXlab platform
Yoshiyuki Kondo - One of the best experts on this subject based on the ideXlab platform.
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a quantitative approach to evaluate fretting fatigue limit using a pre Cracked Specimen
Tribology International, 2017Co-Authors: Masanobu Kubota, Daisuke Takazaki, Shunsuke Kataoka, Yoshiyuki KondoAbstract:Abstract A pre-Cracked Specimen, which has a 70-μm-deep crack, was used for the fretting fatigue test to understand the reasons for the change in the fretting fatigue limit due to changes in the contact pressure, position of the pre-crack, and foot length of the contact pad. The threshold stress intensity factor range to crack propagation of the pre-crack, ΔKth, was obtained by the crack growth test. The stress intensity factor range of the pre-crack under fretting conditions was then evaluated by a finite element analysis to estimate the fretting fatigue limit of the pre-crack Specimen. The effects of these variables on the fretting fatigue limit were quantitatively explained by the results of the FEM and ΔKth of the short crack.
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effect of absorbed hydrogen on the near threshold fatigue crack growth behavior of short crack examination on low alloy steel carbon steel and heat resistant alloy a286
Transactions of the Japan Society of Mechanical Engineers. A, 2008Co-Authors: Yoshiyuki Kondo, Masanobu Kubota, Keiko Shishime, Jun Ichiro YamaguchiAbstract:Hydrogen is considered to be a possible energy source in the coming future. However, it has been recognized that hydrogen has a detrimental effect on the fatigue strength of metal. The fatigue crack growth characteristic is an important property for the integrity assessment of hydrogen utilization machine. In this report, the effect of absorbed hydrogen on the fatigue crack propagation characteristic in the near threshold regime was studied using low alloy steel, carbon steels and heat resistant alloy A286. Especially in this study, very short pre-Cracked Specimen as small as 0.03 mm deep was used. As a result, materials with Vickers hardness higher than 300 were susceptible to absorbed hydrogen irrespective of alloy system. Fatigue crack propagation was accelerated and the ΔKth was lowered about 25%. No remarkable change was observed in materials with hardness lower than 200.
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effect of absorbed hydrogen on the near threshold fatigue crack growth behavior of short crack
Materials Science Forum, 2007Co-Authors: Keiko Shishime, Masanobu Kubota, Yoshiyuki KondoAbstract:Hydrogen is considered to be a possible energy source in the coming future. However, it has been recognized that hydrogen has a detrimental effect on the fatigue strength of metal. The fatigue crack growth characteristic is an important property for the integrity assessment of hydrogen utilization machine. In this report, the effect of hydrogen on the fatigue crack propagation characteristic was studied using low alloy steel, carbon steels and A286 alloy. Especially in this study, very short pre-Cracked Specimen as small as 0.03 mm deep was used and the near threshold fatigue crack behavior was studied. As a result, materials whose Vickers hardness was higher than 300 were found to be susceptible to absorbed hydrogen.
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evaluation of fretting fatigue limit based on local stress at the contact edge
Journal of The Society of Materials Science Japan, 2002Co-Authors: Yoshiyuki Kondo, Chu Sakae, Masanobu Kubota, Tomohiro Nagasue, Shinichi SatoAbstract:It was reported previously by the author that the effect of various factors influencing the fretting fatigue limit could be evaluated based on the local stress at the contact edge. In this report, the meaning of the local stress in fretting fatigue was studied. The two-step fatigue test showed that the value of the local stress fatigue limit was nearly the same as the fatigue limit of an edge Cracked Specimen containing a non-propagating crack formed by the pre-fretting fatigue. The change of stress intensity factor due to the crack growth under fretting fatigue condition was calculated by FEM. The fretting fatigue limit was the condition at which a micro-crack generated by fretting remains as a non-propagating crack. The condition to form a non-propagating crack in fretting fatigue was evaluated on the basis of the threshold condition of short fatigue crack growth.
Masanobu Kubota - One of the best experts on this subject based on the ideXlab platform.
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a quantitative approach to evaluate fretting fatigue limit using a pre Cracked Specimen
Tribology International, 2017Co-Authors: Masanobu Kubota, Daisuke Takazaki, Shunsuke Kataoka, Yoshiyuki KondoAbstract:Abstract A pre-Cracked Specimen, which has a 70-μm-deep crack, was used for the fretting fatigue test to understand the reasons for the change in the fretting fatigue limit due to changes in the contact pressure, position of the pre-crack, and foot length of the contact pad. The threshold stress intensity factor range to crack propagation of the pre-crack, ΔKth, was obtained by the crack growth test. The stress intensity factor range of the pre-crack under fretting conditions was then evaluated by a finite element analysis to estimate the fretting fatigue limit of the pre-crack Specimen. The effects of these variables on the fretting fatigue limit were quantitatively explained by the results of the FEM and ΔKth of the short crack.
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effect of absorbed hydrogen on the near threshold fatigue crack growth behavior of short crack examination on low alloy steel carbon steel and heat resistant alloy a286
Transactions of the Japan Society of Mechanical Engineers. A, 2008Co-Authors: Yoshiyuki Kondo, Masanobu Kubota, Keiko Shishime, Jun Ichiro YamaguchiAbstract:Hydrogen is considered to be a possible energy source in the coming future. However, it has been recognized that hydrogen has a detrimental effect on the fatigue strength of metal. The fatigue crack growth characteristic is an important property for the integrity assessment of hydrogen utilization machine. In this report, the effect of absorbed hydrogen on the fatigue crack propagation characteristic in the near threshold regime was studied using low alloy steel, carbon steels and heat resistant alloy A286. Especially in this study, very short pre-Cracked Specimen as small as 0.03 mm deep was used. As a result, materials with Vickers hardness higher than 300 were susceptible to absorbed hydrogen irrespective of alloy system. Fatigue crack propagation was accelerated and the ΔKth was lowered about 25%. No remarkable change was observed in materials with hardness lower than 200.
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effect of absorbed hydrogen on the near threshold fatigue crack growth behavior of short crack
Materials Science Forum, 2007Co-Authors: Keiko Shishime, Masanobu Kubota, Yoshiyuki KondoAbstract:Hydrogen is considered to be a possible energy source in the coming future. However, it has been recognized that hydrogen has a detrimental effect on the fatigue strength of metal. The fatigue crack growth characteristic is an important property for the integrity assessment of hydrogen utilization machine. In this report, the effect of hydrogen on the fatigue crack propagation characteristic was studied using low alloy steel, carbon steels and A286 alloy. Especially in this study, very short pre-Cracked Specimen as small as 0.03 mm deep was used and the near threshold fatigue crack behavior was studied. As a result, materials whose Vickers hardness was higher than 300 were found to be susceptible to absorbed hydrogen.
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evaluation of fretting fatigue limit based on local stress at the contact edge
Journal of The Society of Materials Science Japan, 2002Co-Authors: Yoshiyuki Kondo, Chu Sakae, Masanobu Kubota, Tomohiro Nagasue, Shinichi SatoAbstract:It was reported previously by the author that the effect of various factors influencing the fretting fatigue limit could be evaluated based on the local stress at the contact edge. In this report, the meaning of the local stress in fretting fatigue was studied. The two-step fatigue test showed that the value of the local stress fatigue limit was nearly the same as the fatigue limit of an edge Cracked Specimen containing a non-propagating crack formed by the pre-fretting fatigue. The change of stress intensity factor due to the crack growth under fretting fatigue condition was calculated by FEM. The fretting fatigue limit was the condition at which a micro-crack generated by fretting remains as a non-propagating crack. The condition to form a non-propagating crack in fretting fatigue was evaluated on the basis of the threshold condition of short fatigue crack growth.
Hiroshi Noguchi - One of the best experts on this subject based on the ideXlab platform.
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effects of hydrogen altered yielding and work hardening on plastic zone evolution a finite element analysis
International Journal of Hydrogen Energy, 2015Co-Authors: Daisuke Sasaki, Motomichi Koyama, Kenji Higashida, Kaneaki Tsuzaki, Hiroshi NoguchiAbstract:Abstract In the present paper, finite-element analysis of a Cracked Specimen was conducted using a unified model for the elastic–plastic deformation and hydrogen diffusion. We considered the effects of the hydrogen-reduced yielding strength and work-hardening coefficient and used a comparison parameter in the simulation of the hydrogen-localized plastic zone near a crack tip. We realized two important facts: (1) the normal component of the plastic strain in the direction of remote stress near the crack tip is significantly increased by the reduced work-hardening coefficient at the same stress-intensity factor; (2) the reduced work-hardening coefficient enhances the localization of the plastic zone when compared to the case using the normal component of the crack-tip plastic strain in the direction of remote stress, which probably determines the ductile–brittle transition of the fatigue-crack propagation mode under a hydrogen atmosphere. These results indicate that the reduction in work-hardening coefficient and the utilization of the crack-tip plastic strain as a parameter to organize the data play important roles in the prediction of the transition condition of hydrogen-accelerated fatigue-crack propagation.
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engineering definitions of small crack and long crack at fatigue limit under tensile mean stress and a prediction method for determining the fatigue limit of a Cracked mg alloy
International Journal of Fatigue, 2013Co-Authors: Shigeru Hamada, Takuya Kinoshita, Kazunori Morishige, Komei Hayashi, Toshiyuki Ishina, Hiroshi NoguchiAbstract:Abstract A simple method was proposed for evaluating the influence of mean stress on the fatigue limit of a Cracked Specimen using engineering approximations. Three types of crack sizes were introduced for evaluation: an “extra small crack,” a “small crack,” and a “long crack”. The threshold stress intensity factor range was shown for each size based on crack non-propagation behavior using physical foundations. The effect of mean stress on the fatigue limit of the Cracked Specimen was formulated, and fatigue tests were performed on a magnesium alloy to check the approximation errors, which were found to be almost within 10%. Furthermore, the small-long crack transition was characterized experimentally.
Kotoji Ando - One of the best experts on this subject based on the ideXlab platform.
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threshold stress during crack healing treatment of structural ceramics having the crack healing ability
Materials Letters, 2007Co-Authors: Wataru Nakao, Koji Takahashi, Kotoji AndoAbstract:Alumina/15 vol.% SiC particles composite and mullite/15 vol.% SiC particles composite, that have excellent crack-healing ability are subjected to crack-healing under elevated static and cyclic stresses at 1373 K or 1473 K. The bending strengths of the Specimens crack-healed under stress were investigated at the crack-healing temperature. From the results, the threshold stresses during crack-healing were determined. Crack-healing was found to occur although the pre-crack is grown by the applied stress. It is found that crack-healing can eliminate the pre-crack under stress below 64% fracture stress of the Cracked Specimen, if the ceramic components have an adequate crack-healing ability.
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a preliminary study on crack healing behaviour of si3 n4 sic composite ceramics
Fatigue & Fracture of Engineering Materials & Structures, 1998Co-Authors: Kotoji Ando, T Ikeda, S Sato, F Yao, Y KobayasiAbstract:Ceramic (Si3 N4 /SiC) composites have been produced by sintering. From the sintered block, three point bend Specimens were cut out. A semi-circular crack was made on the centre of the tension surface of the test Specimen with the aid of a Vicker’s indenter. The diameter of the semi-circular crack was about 60–70 μm. The Specimens were subsequently heat treated at 1300°C for 1 h in vacuum, nitrogen or air. The bending strength was measured at room temperature, 800 and 1000°C. The Specimens heat treated in air recovered considerably their bending strength at 1000°C, several Specimens failed at a location different from the healed crack and their average strength showed the same value of that for smooth Specimens. From these results, it is concluded that the recovery in bending strength of a Cracked Specimen was caused by crack healing.
Tanguy Rouxel - One of the best experts on this subject based on the ideXlab platform.
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fracture toughness fracture energy and slow crack growth of glass as investigated by the single edge preCracked beam sepb and chevron notched beam cnb methods
Acta Materialia, 2018Co-Authors: Fabrice Celarie, Clement Rouxlanglois, Arnaud Bazin, Yann Gueguen, Herve Orain, Mickael Le Fur, Vincent Burgaud, Tanguy RouxelAbstract:Abstract We show that the Single-Edge PreCracked Beam (SEPB) test is not only suitable to the determination of the fracture toughness (KIc) of glass, but also offers a unique opportunity to assess the slow crack growth behavior in a single experiment lasting for few minutes. Besides, we found that it is possible to get either a stable or an unstable final fracture regime (pre-Cracked Specimen) depending on the testing parameters, and that the unstable case is preferable for the estimation of KIc. The "pop-in" precrack was found mostly to close completely once the load was suppressed on the bridge-flexure device. This led to a reopening event on the loading curves. It is noteworthy that all these original observations were made possible thanks to the design of a very stiff testing apparatus (6.7 MN m−1) allowing for a cross-head speed as small as 0.01 μm s−1. Results obtained on four grades of commercially available glasses are compared to those stemming from Vickers indentation cracking and chevron notched experiments.