The Experts below are selected from a list of 16506 Experts worldwide ranked by ideXlab platform
Vancanh Tong - One of the best experts on this subject based on the ideXlab platform.
-
internal loads and contact pressure distributions on the main shaft bearing in a modern gearless wind turbine
Tribology International, 2020Co-Authors: Jingyang Zheng, Shan Yin, Vancanh TongAbstract:Abstract The double-row tapered roller bearing (TRB) widely used to support the main shaft in a modern gearless wind turbine is one of the main components and its faults can lead to the malfunctions and downtime of wind turbines. Over the past decades, some numerical approaches have been proposed for calculating the contact Force and pressure distribution of double-row TRBs. Nevertheless, most of the existing studies did not take the angular misalignment between inner and outer rings and the Frictional Force between the rollers and raceways into account. This paper presents a comprehensive quasi-static model to investigate the internal load and contact pressure distribution in a double-row TRB by considering the angular misalignment, the combined external loads and Frictional Force. It is found that a small misalignment angle between inner and outer rings can result in a significant change in the magnitude and distribution of the contact Force and pressure. The double-row TRB with crowned roller profile exhibits a substantial improvement in contact pressure distribution by eliminating the occurrence of pressure concentration. Moreover, the peak contact pressure can be significantly reduced on the roller with the crowned profile, even if in the case of misaligned bearing. Comparisons of the simulated contact loads and pressure distributions demonstrate the necessity of considering angular misalignment and Frictional Force in the modelling of large size and heavily loaded double-row TRB.
Seizo Morita - One of the best experts on this subject based on the ideXlab platform.
-
atomic scale friction observed with a two dimensional Frictional Force microscope
Physical Review B, 1995Co-Authors: Satoru Fujisawa, Yasuhiro Sugawara, Eigo Kishi, Seizo MoritaAbstract:Using the two-dimensional Frictional-Force microscope, we studied the two-dimensional nature of the atomic-scale friction between a ${\mathrm{Si}}_{3}$${\mathrm{N}}_{4}$ tip and the cleaved ${\mathrm{MoS}}_{2}$ surface. As a result, we confirmed the existence of two-dimensionally discrete friction with the lattice periodicity of the ${\mathrm{MoS}}_{2}$ surface. In addition to the well-known stick-slip behavior, we found the appearance of friction with square-wave behavior which works across the scanning direction, although it is contradictory to the assumption of classical friction. We found that this friction is due to spatially discrete adhesion and jumps with the lattice periodicity, which is explained by the two-dimensional stick-slip model not only qualitatively but also quantitatively. We also observed the fluctuation of the discrete jumps. Further, using the two-dimensional stick-slip model with an effective adhesive radius, we explain the sawtooth and square-wave behaviors due to each discrete jump in more detail.
-
Fluctuation in Two-Dimensional Stick-Slip Phenomenon Observed with Two-Dimensional Frictional Force Microscope.
Japanese Journal of Applied Physics, 1994Co-Authors: Satoru Fujisawa, Yasuhiro Sugawara, E. Kishi, Seizo MoritaAbstract:We used an atomic Force microscope combined with a lateral Force microscope (AFM/LFM) as a two-dimensional Frictional Force microscope (2D-FFM) to investigate the two-dimensional behavior of the atomic-scale friction between the cleaved surface of MoS 2 and the Si 3 N 4 tip apex of the microcantilever based on the two-dimensional stick-slip model. As a result, for the scan direction along the row of the stick-points, we found the unstable state where the tip apex shows fluctuation between two adjacent rows of stick-points. On the other hand, near the row of the stick-points, we also found the stable state where the tip apex takes a straight walk on a row of the stick-points without fluctuation
Jingyang Zheng - One of the best experts on this subject based on the ideXlab platform.
-
internal loads and contact pressure distributions on the main shaft bearing in a modern gearless wind turbine
Tribology International, 2020Co-Authors: Jingyang Zheng, Shan Yin, Vancanh TongAbstract:Abstract The double-row tapered roller bearing (TRB) widely used to support the main shaft in a modern gearless wind turbine is one of the main components and its faults can lead to the malfunctions and downtime of wind turbines. Over the past decades, some numerical approaches have been proposed for calculating the contact Force and pressure distribution of double-row TRBs. Nevertheless, most of the existing studies did not take the angular misalignment between inner and outer rings and the Frictional Force between the rollers and raceways into account. This paper presents a comprehensive quasi-static model to investigate the internal load and contact pressure distribution in a double-row TRB by considering the angular misalignment, the combined external loads and Frictional Force. It is found that a small misalignment angle between inner and outer rings can result in a significant change in the magnitude and distribution of the contact Force and pressure. The double-row TRB with crowned roller profile exhibits a substantial improvement in contact pressure distribution by eliminating the occurrence of pressure concentration. Moreover, the peak contact pressure can be significantly reduced on the roller with the crowned profile, even if in the case of misaligned bearing. Comparisons of the simulated contact loads and pressure distributions demonstrate the necessity of considering angular misalignment and Frictional Force in the modelling of large size and heavily loaded double-row TRB.
R S Dwyerjoyce - One of the best experts on this subject based on the ideXlab platform.
-
the effects of oil groove position on torque and Frictional Force in hydrodynamic journal bearing
Applied Mechanics and Materials, 2013Co-Authors: Mohamad Ali Ahmad, Salmiah Kasolang, R S Dwyerjoyce, Mimi Azlina Abu BakarAbstract:Axial groove is a common supply method of distributing lubricant within a journal bearing. Lubricant is generally fed at a specific supply pressure to ensure that the journal and the bearing surface are separated. Shearing action between lubricant and bearing parts creates frictions which contribute to power loss in journal bearing. In the present study, an experimental work was conducted to determine the effect of oil groove location on torque and Frictional Force in hydrodynamic journal bearing. A journal diameter of 100mm with a 12 length-to-diameter ratio was used. The oil supply pressure was set at 0.20 to 0.25 MPa. The groove was positioned at 3 different locations namely 00, +150and +300. Measurements of torque and Frictional Force were obtained for speed values of 300, 500 and 800 RPM at different radial loads. It was observed that the change in oil groove location has affected the fluid Frictional Force and friction coefficient to some extent.
-
experimental study of oil supply pressure effects on bearing friction in hydrodynamic lubrication
Applied Mechanics and Materials, 2013Co-Authors: Mohamad Ali Ahmad, Salmiah Kasolang, R S DwyerjoyceAbstract:Journal bearing is widely applied in most of rotating machineries for transmission of large loads at mean speed of rotation. Friction caused by the shearing condition between journal, bearing and lubricant contribute to power loses in journal bearing system. In the present study, an experimental work was conducted to determine the effect of oil supply pressure on Frictional Force, friction coefficient and torque of a journal bearing. A journal diameter of 100 mm with a ½ length-to-diameter ratio was used. The oil supply pressure was set at three different values (0.3, 0.5, 0.7 MPa). Frictional Force and friction coefficient results for 400, 600 and 800 RPM at different radial loads were obtained. It was observed that the change in oil supply pressure has affected the fluid Frictional Force and friction coefficient to some extent.
-
the effects of oil supply pressure at different groove position on Frictional Force and torque in journal bearing lubrication
Procedia Engineering, 2013Co-Authors: Mohamad Ali Ahmad, Salmiah Kasolang, R S DwyerjoyceAbstract:Abstract An axial groove is a common supply method for distributing lubricant within a journal bearing. Lubricant is generally fed at a specific supply pressure to ensure that the journal and the bearing surface are separated. Shearing action between lubricant and bearing parts creates friction which contributes to power loss in the bearing. In this study, experimental work was conducted to determine the effect of oil supply pressure at different oil groove positions on torque and Frictional Force in hydrodynamic journal bearing. The journal bearing test rig with a journal diameter of 100 mm and a length-to-diameter ratio of ½ was used. The oil supply pressure was set at 0.2, 0.5 and 0.7 MPa. The groove was positioned at 7 different locations of -45 0 , -30 0 , -15 0 , 0 0 , +15 0 , +30 0 and +45 0 . Measurements of Frictional Force, torque and friction coefficient were obtained for speed values of 500 and 800 rpm at 10 and 15 kN radial loads. It was found that oil supply pressure and groove positions had affected the Frictional Force and torque in journal bearing.
Masaru Tsukada - One of the best experts on this subject based on the ideXlab platform.
-
atomic scale friction image of graphite in atomic Force microscopy
Physical Review B, 1996Co-Authors: Naruo Sasaki, Katsuyoshi Kobayashi, Masaru TsukadaAbstract:We theoretically investigated the image of atomic-scale friction of graphite in atomic-Force microscopy ~AFM!, based on numerical simulation for a static model. We performed systematic calculations of lateral Force images of AFM aiming to clarify the effects of cantilever stiffness, scan direction, anisotropy of the cantilever, and surface deformation. The simulation is performed for a simple atomistic model with a singleatom tip connected with the cantilever spring scanned on a monolayer graphite surface. The process in which the conservative lateral Force becomes a nonconservative Frictional Force is clarified. ‘‘Stick regions’’ of the tip atom are also discussed in relation to the cantilever stiffness. Calculated Frictional-Force image patterns are in good agreement with experimental ones. We also find the supercell Frictional-Force images and discuss their mechanisms. @S0163-1829~96!01727-4#
