The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Koji Fukagata - One of the best experts on this subject based on the ideXlab platform.
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Microelectromechanical Systems–Based Feedback Control of Turbulence for Skin Friction Reduction
Annual Review of Fluid Mechanics, 2009Co-Authors: Nobuhide Kasagi, Yuji Suzuki, Koji FukagataAbstract:This article focuses on the feedback control of turbulence for skin Friction Reduction and reviews the state of the art of control algorithms and distributed microsensors and microactuators. From a viewpoint of possible practical applications, we discuss only the control schemes based on the wall-surface sensing of shear stress and pressure fluctuations with their assessment in direct numerical simulation. The rapid development of microelectromechanical systems (MEMS) flow sensors/actuators is sketched, and a prototype feedback control system assembled for a turbulent channel flow is introduced. Finally, several major remaining issues in control algorithms and massive fabrication of microdevices are discussed.
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microelectromechanical systems based feedback control of turbulence for skin Friction Reduction
Annual Review of Fluid Mechanics, 2009Co-Authors: Nobuhide Kasagi, Yuji Suzuki, Koji FukagataAbstract:This article focuses on the feedback control of turbulence for skin Friction Reduction and reviews the state of the art of control algorithms and distributed microsensors and microactuators. From a viewpoint of possible practical applications, we discuss only the control schemes based on the wall-surface sensing of shear stress and pressure fluctuations with their assessment in direct numerical simulation. The rapid development of microelectromechanical systems (MEMS) flow sensors/actuators is sketched, and a prototype feedback control system assembled for a turbulent channel flow is introduced. Finally, several major remaining issues in control algorithms and massive fabrication of microdevices are discussed.
Nobuhide Kasagi - One of the best experts on this subject based on the ideXlab platform.
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Microelectromechanical Systems–Based Feedback Control of Turbulence for Skin Friction Reduction
Annual Review of Fluid Mechanics, 2009Co-Authors: Nobuhide Kasagi, Yuji Suzuki, Koji FukagataAbstract:This article focuses on the feedback control of turbulence for skin Friction Reduction and reviews the state of the art of control algorithms and distributed microsensors and microactuators. From a viewpoint of possible practical applications, we discuss only the control schemes based on the wall-surface sensing of shear stress and pressure fluctuations with their assessment in direct numerical simulation. The rapid development of microelectromechanical systems (MEMS) flow sensors/actuators is sketched, and a prototype feedback control system assembled for a turbulent channel flow is introduced. Finally, several major remaining issues in control algorithms and massive fabrication of microdevices are discussed.
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microelectromechanical systems based feedback control of turbulence for skin Friction Reduction
Annual Review of Fluid Mechanics, 2009Co-Authors: Nobuhide Kasagi, Yuji Suzuki, Koji FukagataAbstract:This article focuses on the feedback control of turbulence for skin Friction Reduction and reviews the state of the art of control algorithms and distributed microsensors and microactuators. From a viewpoint of possible practical applications, we discuss only the control schemes based on the wall-surface sensing of shear stress and pressure fluctuations with their assessment in direct numerical simulation. The rapid development of microelectromechanical systems (MEMS) flow sensors/actuators is sketched, and a prototype feedback control system assembled for a turbulent channel flow is introduced. Finally, several major remaining issues in control algorithms and massive fabrication of microdevices are discussed.
Yuji Suzuki - One of the best experts on this subject based on the ideXlab platform.
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Microelectromechanical Systems–Based Feedback Control of Turbulence for Skin Friction Reduction
Annual Review of Fluid Mechanics, 2009Co-Authors: Nobuhide Kasagi, Yuji Suzuki, Koji FukagataAbstract:This article focuses on the feedback control of turbulence for skin Friction Reduction and reviews the state of the art of control algorithms and distributed microsensors and microactuators. From a viewpoint of possible practical applications, we discuss only the control schemes based on the wall-surface sensing of shear stress and pressure fluctuations with their assessment in direct numerical simulation. The rapid development of microelectromechanical systems (MEMS) flow sensors/actuators is sketched, and a prototype feedback control system assembled for a turbulent channel flow is introduced. Finally, several major remaining issues in control algorithms and massive fabrication of microdevices are discussed.
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microelectromechanical systems based feedback control of turbulence for skin Friction Reduction
Annual Review of Fluid Mechanics, 2009Co-Authors: Nobuhide Kasagi, Yuji Suzuki, Koji FukagataAbstract:This article focuses on the feedback control of turbulence for skin Friction Reduction and reviews the state of the art of control algorithms and distributed microsensors and microactuators. From a viewpoint of possible practical applications, we discuss only the control schemes based on the wall-surface sensing of shear stress and pressure fluctuations with their assessment in direct numerical simulation. The rapid development of microelectromechanical systems (MEMS) flow sensors/actuators is sketched, and a prototype feedback control system assembled for a turbulent channel flow is introduced. Finally, several major remaining issues in control algorithms and massive fabrication of microdevices are discussed.
Marcelo J. Dapino - One of the best experts on this subject based on the ideXlab platform.
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Mapping of power consumption and Friction Reduction in piezoelectrically-assisted ultrasonic lubrication
Industrial and Commercial Applications of Smart Structures Technologies 2015, 2015Co-Authors: Sheng Dong, Marcelo J. DapinoAbstract:Ultrasonic lubrication has been proven effective in reducing dynamic Friction. This paper investigates the relationship between Friction Reduction, power consumption, linear velocity, and normal stress. A modified pin-on-disc tribometer was adopted as the experimental set-up, and a Labview system was utilized for signal generation and data acquisition. Friction Reduction was quantified for 0.21 to 5.31 W of electric power, 50 to 200 mm/s of linear velocity, and 23 to 70 MPa of normal stress. Friction Reduction near 100% can be achieved under certain conditions. Lower linear velocity and higher electric power result in greater Friction Reduction, while normal stress has little effect on Friction Reduction. Contour plots of Friction Reduction, power consumption, linear velocity, and normal stress were created. An efficiency coefficient was proposed to calculate power requirements for a certain Friction Reduction or reduced Friction for a given electric power.
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elastic plastic cube model for ultrasonic Friction Reduction via poisson s effect
Ultrasonics, 2014Co-Authors: Sheng Dong, Marcelo J. DapinoAbstract:Abstract Ultrasonic Friction Reduction has been studied experimentally and theoretically. This paper presents a new elastic–plastic cube model which can be applied to various ultrasonic lubrication cases. A cube is used to represent all the contacting asperities of two surfaces. Friction force is considered as the product of the tangential contact stiffness and the deformation of the cube. Ultrasonic vibrations are projected onto three orthogonal directions, separately changing contact parameters and deformations. Hence, the overall change of Friction forces. Experiments are conducted to examine ultrasonic Friction Reduction using different materials under normal loads that vary from 40 N to 240 N. Ultrasonic vibrations are generated both in longitudinal and vertical (out-of-plane) directions by way of the Poisson effect. The tests show up to 60% Friction Reduction; model simulations describe the trends observed experimentally.
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Characterisation of Friction Reduction with tangential ultrasonic vibrations using a SDOF model
International Journal of Vehicle Design, 2013Co-Authors: Shravan Bharadwaj, Marcelo J. DapinoAbstract:Active control of Friction between sliding surfaces is of fundamental and practical interest in automotive applications. It has been shown that the Friction force between sliding surfaces decreases when ultrasonic vibration is superimposed on the sliding motion. This principle can be applied to systems in which solid state lubrication or Friction modulation is advantageous. The ultrasonic vibration may be applied longitudinally or normal to the direction of motion. A number of Friction models have been considered in order to analyse this phenomenon. The degree of Friction Reduction has been shown to depend on the ratio of the sliding velocity to the vibration velocity. Since Friction is a system response, it is necessary to include system dynamics in the analysis of ultrasonic lubrication. A nonlinear single-degree-offreedom-model is formulated and numerically approximated to quantify the effect on Friction Reduction of control force, intrinsic coefficient of Friction, mass load, tangential contact stiffness at the sliding interface, and system stiffness. Model results are in close agreement with experimental measurements.
James Edward Colgate - One of the best experts on this subject based on the ideXlab platform.
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The contribution of air to ultrasonic Friction Reduction
2017Co-Authors: Rebecca Fenton Friesen, Michael Wiertlewski, Michael Peshkin, James Edward ColgateAbstract:— The origin of Friction Reduction on an ultrason-ically vibrating plate has been the subject of debate. Recent work suggests that Friction may be reduced due to intermittent contact caused by bouncing upon the vibrating surface [8], leaving the question of whether other phenomena such as levitation on a squeeze film of air also play a role. To probe the contribution of squeeze film levitation, we investigated the dependence of the Friction Reduction effect upon air pressure. An artificial finger was placed inside a vacuum chamber, touching an ultrasonic Friction Reduction device composed of a glass plate vibrated by piezo-actuators. Friction between the finger and the glass was measured by rotating the finger with a motor, and measuring the motor's torque load. Decreased Friction is signaled by decreased motor current. Compared to atmospheric pressure, a 98% vacuum inside the chamber was observed to markedly diminish the Friction Reduction effect, suggesting that squeeze film levitation does indeed play a substantial role in ultrasonic Friction Reduction.
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WHC - The contribution of air to ultrasonic Friction Reduction
2017 IEEE World Haptics Conference (WHC), 2017Co-Authors: Rebecca Fenton Friesen, Michael Wiertlewski, Michael Peshkin, James Edward ColgateAbstract:The origin of Friction Reduction on an ultrasonically vibrating plate has been the subject of debate. Recent work suggests that Friction may be reduced due to intermittent contact caused by bouncing upon the vibrating surface [1], leaving the question of whether other phenomena such as levitation on a squeeze film of air also play a role. To probe the contribution of squeeze film levitation, we investigated the dependence of the Friction Reduction effect upon air pressure. An artificial finger was placed inside a vacuum chamber, touching an ultrasonic Friction Reduction device composed of a glass plate vibrated by piezo-actuators. Friction between the finger and the glass was measured by rotating the finger with a motor, and measuring the motor's torque load. Decreased Friction is signaled by decreased motor current. Compared to atmospheric pressure, a 98% vacuum inside the chamber was observed to markedly diminish the Friction Reduction effect, suggesting that squeeze film levitation does indeed play a substantial role in ultrasonic Friction Reduction.
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The role of damping in ultrasonic Friction Reduction
IEEE Haptics Symposium HAPTICS, 2016Co-Authors: Rebecca Fenton Friesen, Michael Wiertlewski, James Edward ColgateAbstract:We observed the dynamic interaction between a fingertip and an ultrasonically vibrating plate using Laser Doppler Vibrometry in order to investigate the causes of ultrasonic Friction Reduction. Observations were made both for a human finger and for artificial fingertips constructed to exhibit different amounts of damping. The data suggest that fingertip dynamics play an important role in Friction Reduction. In particular, the fingertips were all found to exhibit forced oscillations in response to the plate motion, but with different relative phases. Fingertips with lower damping oscillated more in-phase with the plate, while fingertips with higher damping oscillated more out-of-phase with the plate, and also exhibited greater Friction Reduction. These results are reflected in a model.
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HAPTICS - The role of damping in ultrasonic Friction Reduction
2016 IEEE Haptics Symposium (HAPTICS), 2016Co-Authors: Rebecca Fenton Friesen, Michael Wiertlewski, James Edward ColgateAbstract:We observed the dynamic interaction between a fingertip and an ultrasonically vibrating plate using Laser Doppler Vibrometry in order to investigate the causes of ultrasonic Friction Reduction. Observations were made both for a human finger and for artificial fingertips constructed to exhibit different amounts of damping. The data suggest that fingertip dynamics play an important role in Friction Reduction. In particular, the fingertips were all found to exhibit forced oscillations in response to the plate motion, but with different relative phases. Fingertips with lower damping oscillated more in-phase with the plate, while fingertips with higher damping oscillated more out-of-phase with the plate, and also exhibited greater Friction Reduction. These results are reflected in a model.
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World Haptics - Bioinspired artificial fingertips that exhibit Friction Reduction when subjected to transverse ultrasonic vibrations
2015 IEEE World Haptics Conference (WHC), 2015Co-Authors: Rebecca Fenton Friesen, Michael Wiertlewski, Michael Peshkin, James Edward ColgateAbstract:This paper presents the design of a bioinspired artificial fingertip that resembles the mechanical behavior of a human fingertip under conditions of both static deformation and high frequency excitation. The artificial fingertip is constructed around a deformable spherical membrane filled with a cellulose sponge, itself connected to a rigid structure that acts as a bone. Force-deformation characteristics and response to a transient mechanical perturbation are both shown to be in good qualitative agreement with those of a real finger. More importantly, the fingertip exhibits Friction Reduction when interacting with TPads (variable Friction tactile displays based on transverse ultrasonic vibrations). Comparison with artificial fingertips that do not exhibit Friction Reduction suggests that mechanical damping characteristics play a key role in the amount of Friction Reduction achieved.
