scholarly journals Experimental Study of Collision Motion, Contact Force and Adhesion Force of Hemispherical Sliders with Stationary Magnetic Disks

2006 ◽  
Vol 49 (4) ◽  
pp. 1159-1170 ◽  
Author(s):  
Kyosuke ONO ◽  
Kenji NAKAGAWA
Keyword(s):  
Experimental Study ◽  
Contact Force ◽  
Adhesion Force ◽  
Magnetic Disks

Experimental Study of Bouncing Behavior of Spherical Sliders on Stationary Magnetic Disks

2005 ◽  
Author(s):  
Kyosuke Ono ◽  
Kenji Nakagawa
Keyword(s):  
Experimental Study ◽  
Contact Force ◽  
Adhesion Force ◽  
Dynamic Contact ◽  
Hertzian Contact ◽  
Magnetic Disks ◽  
Meniscus Force ◽  
Typical Data ◽  
Maximum Contact ◽  
Hertzian Contact Theory

This paper presents experimental study of measuring dynamic contact force and meniscus force from the bouncing motion of hemispherical sliders on stationary magnetic disks. Two hemispherical sliders of 1.0mm and 2.0mm radii and test disks with 1, 2, 3 nm thick lubricants with/without UV treatment are used for the experiment. Typical data of displacement, velocity and acceleration of bouncing motion shows a clear adhesion force by formation of a meniscus bridge at the end of impact. It is found that the maximum contact force versus penetration depth can be estimated by Hertzian contact theory. The maximum dynamic adhesion force is close to the static meniscus force.

Size and Temperature Dependent Deposition Model of Micro-Sized Sand Particles

2017 ◽  
Author(s):  
Kuahai Yu ◽  
Danesh Tafti
Keyword(s):  
Contact Force ◽  
Adhesion Force ◽  
Stokes Number ◽  
Experimental Result ◽  
Contact Radius ◽  
Recovery Stage ◽  
Line Force ◽  
Plastic Stage ◽  
Sand Particles ◽  
The Impact

Sand ingestion and deposition in gas turbine engine components can lead to several operational hazards. This paper discusses a physics based model for modeling the impact and deposition of sand particles. The collision model divides the impact process into three stages, the elastic stage, the elastic-plastic stage, and full plastic stage. The recovery stage is assumed to be fully elastic. The contact force, contact radius and work of contact force are conformed to the Hertzian theory, using “Young’s modulus similarity” rule to predict the recovery displacement. The adhesion loss in the recovery stage is considered using Dunn’s model, which describes the adhesion force as an idealized line force with the contact radius. The validation case of steel spherical particle impact on a glass surface with the maximum Stokes number of 10000, shows that the adhesion model with elastoplastic impact model describes the experimental result well. When the Stokes number is less than 12, the particle deposits on the surface. Sand properties are characterized by size and temperature dependencies. Model predictions for particle sizes ranging from 0.5 to 50 micron, impact velocities up to 80 m/s, and temperatures above 1300 K are given and discussed. It is shown that both size and temperature have an effect on the deposition characteristics.

Dynamic Indentation Characteristics of Spherical Sliders Colliding With Stationary Magnetic Disks With a Thin Lubricant Layer

2007 ◽  
Author(s):  
Kyosuke Ono ◽  
Kenji Nakagawa
Keyword(s):  
Adhesion Force ◽  
Flying Height ◽  
Lubricant Layer ◽  
Lubricant Thickness ◽  
Dynamic Indentation ◽  
Magnetic Disks ◽  
Strong Adhesion ◽  
The Relationship ◽  
Acting Force ◽  
Interfacial Force

We measured the dynamic adhesion force when spherical sliders with a radius of 1 and 2 mm collided with smooth magnetic disks with lubricant layers of zero, 1, 2, and 3 nm thickness to clarify the dynamic interfacial force between a slider and disk in the nanometer region of flying height. From the measured slider velocity, we calculated the relationship between acceleration (acting force) and displacement. We found that a strong adhesion force observed at zero lubricant vanishes when 1-nm thick lubricant with UV is applied. As the mobile lubricant thickness was increased, we observed a clear dynamic adhesion force at the instant of separation. These results indicate that adhesion force is most likely to result from meniscus formation.

Experimental Identification of Elastic, Damping and Adhesion Forces in Collision of Spherical Sliders With Stationary Magnetic Disks

2004 ◽  
Author(s):  
Kyosuke Ono ◽  
Satoshi Oohara
Keyword(s):  
Adhesion Force ◽  
Contact Theory ◽  
Force Model ◽  
Adhesion Forces ◽  
Lubricant Thickness ◽  
Damping Force ◽  
Magnetic Disks ◽  
Magnetic Disk ◽  
Damping Effect ◽  
Experimental Identification

This paper deals with the experimental identification of elastic, damping and adhesion forces in the dynamic collision of a spherical slider with a stationary magnetic disk. We used rough Al2O3TiC and smooth glass spherical sliders with a radius of 1 mm, and magnetic disks with four different lubricant film thicknesses of 0, 1, 2, and 3 nm. We found that the Al2O3TiC slider shows ordinary approach and rebound processes, whereas the glass slider showed a velocity drop at the end of the rebound process when the lubricant thickness was 1, 2 and 3 nm. We identified the elastic force factors in the approaching and rebound processes, based on the Herztian contact theory, and the damping force factors based on a damping force model that is proportional to slider velocity and penetration depth (contact area). From the drop in velocity when the slider and disk separated, we found that the dynamic adhesion force is almost equal to the static pull-off force, except for with a 3nm lubricant thickness. The dynamic adhesion force with 3 nm lubricant thickness is significantly higher probably because of squeeze damping effect.

Experimental Study of Dynamic Interaction Between a Steam Generator Tube and an Anti-Vibration Bar

2010 ◽  
Author(s):  
V. Lalonde ◽  
A. Ross ◽  
M. J. Pettigrew ◽  
I. Nowlan
Keyword(s):  
Experimental Study ◽  
Dynamic Behavior ◽  
Steam Generator ◽  
Contact Force ◽  
Dynamic Interaction ◽  
Work Rate ◽  
Fretting Wear ◽  
Steam Generators ◽  
Simply Supported ◽  
Excitation Force

A first experimental work was previously carried out to study the dynamic behavior of a tube simply supported at both ends in interaction with an anti-vibration bar at mid-span. This paper presents modifications to the previous setup with the aim of improving the accuracy of the results. A comparison of the dynamic behavior of the tube is made between both setups. The objective of this experimental study is to characterize the vibration behavior of U-tubes found in steam generators of nuclear power plants. Indeed, two-phase cross-flow in the U-tubes section of steam generators can cause many problems related to vibration. In fact, flow-induced vibration of the U-tubes can cause impacts or rubbing of the tubes against their flat bar supports. Variation of the clearance between the AVB and the U-tubes may lead to ineffective supports. The resulting in-plane and out-of-plane motions of the tubes are causing fretting-wear and impact abrasion. In this study, the clearance between the tube and the AVB, as well as the amplitude, form and frequency of the excitation force are controlled parameters. The first two modes of the tube are studied. The modifications made to the setup lead to significant improvements in the results. The natural frequencies of both setups are compared to theoretical values. The difference between experimental and theoretical frequencies confirms that the new setup better represents the theoretical model of a simply supported tube. The damping of both setups is also compared to values found in literature. The results show that the new setup is more representative of realistic steam generator situations. Compared to the first setup, the displacements of the new setup clearly indicate that the movement of the tube is mostly parallel to the flat bar and in the same direction as the excitation force. The whirling motion of the tube is prevented in the new setup. The accuracy of the contact force as a function of clearance was also improved. The use of more sensitive force sensors helped to reduce the noise level of the contact force. Finally, the dynamic interaction between the tube and the AVB, defined by the fretting wear work-rate, presents a more consistent behavior. The maximum work-rate occurs when the tube is excited around the second mode for clearance between −0.10 and 0.00 mm. Such clearance between the tube and the AVB should then be avoided to minimize fretting damage.

Visual, tactile, and contact force feedback: Which one is more important for catheter ablation? Results from an in vitro experimental study

Heart Rhythm ◽  
2014 ◽  
Vol 11 (3) ◽  
pp. 506-513 ◽  
Author(s):  
Luigi Di Biase ◽  
Alessandro Paoletti Perini ◽  
Prasant Mohanty ◽  
Alex S. Goldenberg ◽  
Gino Grifoni ◽  
...  
Keyword(s):  
Experimental Study ◽  
Catheter Ablation ◽  
Contact Force ◽  
Force Feedback

Experimental Identification of Elastic, Damping and Adhesion Forces in Collision of Spherical Sliders With Stationary Magnetic Disks

2005 ◽  
Vol 127 (2) ◽  
pp. 365-375 ◽  
Author(s):  
Kyosuke Ono ◽  
Satoshi Ohara
Keyword(s):  
Adhesion Force ◽  
Contact Theory ◽  
Force Model ◽  
Adhesion Forces ◽  
Lubricant Thickness ◽  
Damping Force ◽  
Magnetic Disks ◽  
Magnetic Disk ◽  
Damping Effect ◽  
Experimental Identification

This paper deals with the experimental identification of elastic, damping and adhesion forces in the dynamic collision of a spherical slider with a stationary magnetic disk. We used rough Al2O3TiC and smooth glass spherical sliders with a radius of 1 mm, and magnetic disks with four different lubricant film thicknesses of 0, 1, 2, and 3 nm. We found that the Al2O3TiC slider shows ordinary approach and rebound processes, whereas the glass slider showed a velocity drop at the end of the rebound process when the lubricant thickness was 1, 2, and 3 nm. We identified the elastic force factors in the approach and rebound processes, based on Herztian contact theory, and the damping force factors based on a damping force model that is proportional to slider velocity and penetration depth (contact area). From the drop in velocity when the slider and disk separated, we found that the dynamic adhesion force is almost equal to the static pull-off force except for with a 3 nm lubricant thickness. The dynamic adhesion force with a 3 nm lubricant thickness is significantly higher, probably because of squeeze damping effect.

Experimental study on pedestrian contact force under different degrees of crowding

2020 ◽  
Vol 127 ◽  
pp. 104713 ◽  
Author(s):  
Xudong Li ◽  
Weiguo Song ◽  
Xuan Xu ◽  
Jun Zhang ◽  
Long Xia ◽  
...  
Keyword(s):  
Experimental Study ◽  
Contact Force
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