The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Yoshiyuki Furuya - One of the best experts on this subject based on the ideXlab platform.
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High-Temperature Ultrasonic Fatigue Testing at 1000°C
Advanced Materials Research, 2014Co-Authors: Yoshiyuki Furuya, Kazuo Kobayashi, Masao Hayakawa, Masao Sakamoto, Yutaka Koizumi, Hiroshi HaradaAbstract:A high-temperature ultrasonic Fatigue Testing system was developed to evaluate the gigacycle Fatigue properties of single-crystal superalloys used in aircraft engine turbine blades. In this development, a commercial ultrasonic Fatigue Testing machine was considerably modified to achieve high-temperature Fatigue Testing. The developed system took account of temperature dependency of Youngs modulus, and also had a function to evaluate the Youngs modulus. In order to protect the Testing system from the heat of a specimen, straight and round rods were inserted between the Testing system and the specimen. Other modifications achieved accurate control of temperature, edge displacement and resonance frequency, which were necessary for accurate control of stress amplitude. The Testing system was first applied to a heat-resistant steel at 650 °C to check its accuracy, and next to SC superalloy samples at 1000 °C. In the conventional Fatigue tests on the heat-resistant steel, the results were coincident in a frequency range from 1 Hz to 800 Hz, suggesting that comparable results would be obtained in ultrasonic Fatigue Testing at 20 kHz. In case of the SC superalloy samples, conventional Fatigue tests were conducted at only 10 Hz, so the frequency effects were not clarified. In both cases, ultrasonic Fatigue Testing showed good agreement with conventional Fatigue Testing. The accuracy of the developed system is therefore high, even at 1000 °C. In these results, the SC superalloys showed no Fatigue limit, indicating gigacycle Fatigue tests to be necessary.
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High-temperature ultrasonic Fatigue Testing of single-crystal superalloys
Materials Letters, 2012Co-Authors: Yoshiyuki Furuya, Kazuo Kobayashi, Masao Hayakawa, Masao Sakamoto, Yutaka Koizumi, Hiroshi HaradaAbstract:Abstract A high-temperature ultrasonic Fatigue Testing system was developed to evaluate the gigacycle Fatigue properties of single-crystal superalloys used in aircraft engine turbine blades. In this development, a commercial ultrasonic Fatigue Testing machine was considerably modified to achieve high-temperature Fatigue Testing. The Testing system was first applied to a heat-resistant steel at 650 °C to check its accuracy, and next to SC superalloy samples at 1000 °C. As a result, the ultrasonic Fatigue Testing showed good agreement with the conventional Fatigue Testing, demonstrating the high accuracy of the developed system. In these results, the SC superalloys showed no Fatigue limit, indicating gigacycle Fatigue tests to be necessary.
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Recent Researches on Gigacycle Fatigue using Ultrasonic Fatigue Testing in NIMS
2011Co-Authors: Yoshiyuki FuruyaAbstract:Gigacycle Fatigue takes place in high-strength steel. In this case, fish-eye fracture eliminates a conventional Fatigue limit. This means that the fish-eye fracture is a key to understand the gigacycle Fatigue of high-strength steel. Evaluation of gigacycle Fatigue properties needs accelerated Fatigue Testing since gigacycle Fatigue tests take long time. For example, a 109-cycles Fatigue test takes more than 3 months at conventional 100 Hz. For this acceleration, ultrasonic Fatigue Testing is a very powerful tool since it achieves 20 kHz and completes the 109-cycles in a day. However, frequency effects must sufficiently be investigated before using the ultrasonic Fatigue Testing.
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size effects in gigacycle Fatigue of high strength steel under ultrasonic Fatigue Testing
Procedia Engineering, 2010Co-Authors: Yoshiyuki FuruyaAbstract:Abstract Ultrasonic Fatigue Testing was conducted for high-strength steel using enlarged specimens with a straight section. The results showed good agreement with conventional servo-hydraulic Fatigue test results under conditions where fish-eye fracture occurs, showing the validity of ultrasonic Fatigue Testing using the enlarged specimens. When the results were compared with those using conventional specimens, size effects were clearly observed: enlarged specimens showed lower Fatigue strength due to appearance of larger inclusions in the fish-eye fracture origin.
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specimen size effects on gigacycle Fatigue properties of high strength steel under ultrasonic Fatigue Testing
Scripta Materialia, 2008Co-Authors: Yoshiyuki FuruyaAbstract:Ultrasonic Fatigue Testing was conducted for high-strength steel, employing enlarged specimens with a straight section. The results showed good agreement with conventional servohydraulic Fatigue test results, demonstrating the validity of ultrasonic Fatigue Testing using these enlarged specimens under conditions where fish-eye fractures occur. When the results were compared with those using conventional specimens, specimen size effects were clearly observed: enlarged specimens showed lower Fatigue strength due to appearance of larger inclusions in the fish-eye fracture origin.
Gianluca Gambarini - One of the best experts on this subject based on the ideXlab platform.
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a review of cyclic Fatigue Testing of nickel titanium rotary instruments
Journal of Endodontics, 2009Co-Authors: Gianluca Plotino, Nicola M Grande, Massimo Cordaro, Luca Testarelli, Gianluca GambariniAbstract:Introduction: Fractured rotary nickel-titanium (NiTi) instruments have been classified into those that fail as a result of cyclic flexural Fatigue or torsional failure or a combination of both. Clinically, NiTi rotary instruments are subjected to both torsional load and cyclic Fatigue, and ongoing research aims to clarify the relative contributions of both factors to instrument separation. Methods: To date, there is no specification or international standard to test cyclic Fatigue resistance of endodontic rotary instruments. As a consequence, several devices and methods have been used to investigate in vitro cyclic Fatigue fracture resistance of NiTi rotary endodontic instruments. In nearly all studies reported in the endodontic literature, the rotating instrument was either confined in a glass or metal tube, in a grooved block-and-rod assembly, or in a sloped metal block. Results: There has been no mention of the ‘‘fit’’ of the instrument in the tube or groove. As the instrument is likely to be fitting loosely, the description of the radius of curvature in those studies is likely to be overstated (ie, the file was actually bent less severely than reported, adding a variability in the amount of flexural stress). Conclusions: This review analyzed several devices that have been used in endodontic literature for cyclic Fatigue Testing and found that differences in the methodology affected the Fatigue behavior of rotary instruments and, consequently, the outcome of these studies. An international standard for cyclic Fatigue Testing of NiTi rotary instruments is required to ensure uniformity of methodology and comparable results. (J Endod 2009;35:1469‐1476)
Carlo Prati - One of the best experts on this subject based on the ideXlab platform.
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cyclic Fatigue Testing and metallographic analysis of nickel titanium rotary instruments
Journal of Endodontics, 2011Co-Authors: Chiara Pirani, Pier Paolo Cirulli, Stefano Chersoni, Lorenzo Micele, Oddone Ruggeri, Carlo PratiAbstract:Abstract Introduction The aim of this study was to compare cyclic Fatigue resistance of four nickel-titanium rotary systems and to evaluate their surface, fractographic, and matrix morphology. Methods Four models of endodontic rotary files (EasyShape [Komet/Gebr. Brasseler, Lemgo, Germany], ProTaper [Dentsply Maillefer, Ballaigues, Switzerland], NRT [MANI Inc, Toshigi-Ken, Japan], and AlphaKite [Komet/Gebr. Brasseler]) were subjected to Fatigue Testing in artificial canals with angle of curvature of 45° and 60° and a radius of curvature of 5 mm until fracture occurred. Nickel-titanium (NiTi) alloy properties were investigated by light microscopy, environmental scanning electron microscopy (ESEM), and energy dispersive x-ray spectrophotometry (EDS). ESEM analysis was conducted on new files to examine surface characteristics and on fractured samples to identify the crack origin and the fractographic features. Results Analysis of variance Testing revealed significant differences ( P Conclusions NRT files presented the longest Fatigue life. All samples showed surface irregularities and nonmetallic inclusions. Austenitic grains were smaller near the tip than near the handle. The angle of curvature was confirmed to influence the Fatigue life of NiTi instruments.
Michel Blanc - One of the best experts on this subject based on the ideXlab platform.
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A new ultrasonic Fatigue Testing device for biaxial bending in the gigacycle regime
International Journal of Fatigue, 2017Co-Authors: Charles Brugger, Pierre Osmond, Thierry Palin-luc, Michel BlancAbstract:A new Fatigue Testing device has been developed to test specimens under biaxial loading at 20 kHz. The specimen is a flat smooth disc. It is placed on a torus frame and cyclically loaded in compression at the center of its upper face. Consequently disc bending generates a biaxial proportional stress state at the center of the specimen lower face. Any positive loading ratio can be applied. This device has been tested and is well functioning on specimens made of a cast aluminum alloy used to produce cylinder heads. Preliminary results in VHCF regime are compared with literature results obtained under similar stress state but in HCF regime and at 20 Hz only.
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Ultrasonic Fatigue Testing device under biaxial bending
Fracture and Structural Integrity, 2016Co-Authors: Charles Brugger, Thierry Palin-luc, Pierre Osmond, Michel BlancAbstract:A new Fatigue Testing device has been developed to test specimens under biaxial loading at 20 kHz. A flat smooth specimen with a disc geometry is placed on a torus frame and cyclically loaded at the center of its upper face. Disc bending generates a biaxial proportional stress state at the center of the lower face. Any positive loading ratio can be applied. A cast aluminum alloy (used to produce cylinder heads) has been tested under biaxial bending using this device in order to determine its Fatigue strength at 109 cycles under high hydrostatic pressure. Self-heating is moderate but macroscopic Fatigue cracks after Testing are very long. First results in VHCF regime are consistent with literature results obtained under similar stress state but in HCF regime and at 20 Hz.
Gianluca Plotino - One of the best experts on this subject based on the ideXlab platform.
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a review of cyclic Fatigue Testing of nickel titanium rotary instruments
Journal of Endodontics, 2009Co-Authors: Gianluca Plotino, Nicola M Grande, Massimo Cordaro, Luca Testarelli, Gianluca GambariniAbstract:Introduction: Fractured rotary nickel-titanium (NiTi) instruments have been classified into those that fail as a result of cyclic flexural Fatigue or torsional failure or a combination of both. Clinically, NiTi rotary instruments are subjected to both torsional load and cyclic Fatigue, and ongoing research aims to clarify the relative contributions of both factors to instrument separation. Methods: To date, there is no specification or international standard to test cyclic Fatigue resistance of endodontic rotary instruments. As a consequence, several devices and methods have been used to investigate in vitro cyclic Fatigue fracture resistance of NiTi rotary endodontic instruments. In nearly all studies reported in the endodontic literature, the rotating instrument was either confined in a glass or metal tube, in a grooved block-and-rod assembly, or in a sloped metal block. Results: There has been no mention of the ‘‘fit’’ of the instrument in the tube or groove. As the instrument is likely to be fitting loosely, the description of the radius of curvature in those studies is likely to be overstated (ie, the file was actually bent less severely than reported, adding a variability in the amount of flexural stress). Conclusions: This review analyzed several devices that have been used in endodontic literature for cyclic Fatigue Testing and found that differences in the methodology affected the Fatigue behavior of rotary instruments and, consequently, the outcome of these studies. An international standard for cyclic Fatigue Testing of NiTi rotary instruments is required to ensure uniformity of methodology and comparable results. (J Endod 2009;35:1469‐1476)
