Meniscus and Viscous Forces during the Nanoscale Separation of Sphere-on-Sphere Contact Surfaces

2011 ◽  
Vol 199-200 ◽  
pp. 739-744
Author(s):  
Si Si Liu ◽  
Chao Hui Zhang ◽  
Han Bing Zhang
Keyword(s):  
Dynamic Contact ◽  
Adhesive Force ◽  
Separation Distance ◽  
Separation Process ◽  
Contact Model ◽  
Viscous Forces ◽  
Fundamental Understanding ◽  
Sphere Contact ◽  
Contact Surfaces ◽  
Nanoscale Separation

When two surfaces are brought into contact or at small separations, the liquid between them forms meniscus, which contributes to adhesion and friction. The increased adhesive force and friction are always the substantial cause leading to micro/nanodevices’s failure. In this study, a dynamic contact model of sphere-on-sphere surfaces during nanoscale separation is presented. A numerical analysis of meniscus and viscous forces based on the dynamic contact model has been carried out. During the separation process, the effects of separation distance, initial meniscus height, surface wettability and separating time on meniscus and viscous forces between the contact surfaces are investigated. The results of numerical solution revealed the adhesion mechanism of sphere-on-sphere surfaces during the separation with liquid mediated. The analyses provide a fundamental understanding of the separating process of two sphere surfaces. It is also useful for the design of the de-wetting and antisticking micro/nanoscale surfaces in various devices.

Adhesion Due to Micro Menisci During Separation of Contact Surfaces

2009 ◽  
Author(s):  
Shaobiao Cai ◽  
Yongli Zhao ◽  
Bharat Bhushan
Keyword(s):  
Surface Roughness ◽  
Relative Motion ◽  
Adhesive Force ◽  
Liquid Films ◽  
Viscous Forces ◽  
Nano Scale ◽  
Macro Scale ◽  
Fundamental Understanding ◽  
Scale Down ◽  
Contact Surfaces

High friction/stiction caused by adhesive force is among the main issues in devices (ranging from macro scale down to mirco/nano scale) having contacting interfaces with relative motion. Relevant parameters, i.e., surface roughness, meniscus and viscous forces due to the presence of liquid films, need to be studied to provide a fundamental understanding of the physics of the experienced problems. The simulations of separation of two surfaces from micro menisci are performed. The roles of the involved forces which contribute to the adhesive force are examined.

Dynamic contact model of shell for multibody system applications

2018 ◽  
Vol 44 (4) ◽  
pp. 335-366 ◽  
Author(s):  
Jiabei Shi ◽  
Zhuyong Liu ◽  
Jiazhen Hong
Keyword(s):  
Multibody System ◽  
Dynamic Contact ◽  
Contact Model

Effects of Digit Orientation on Gecko Adhesive Force Capacity: Synthetic and Behavioral Studies

2019 ◽  
Vol 59 (1) ◽  
pp. 182-192 ◽  
Author(s):  
M J Imburgia ◽  
C -Y Kuo ◽  
D R Briggs ◽  
D J Irschick ◽  
A J Crosby
Keyword(s):  
Adhesive Force ◽  
Model System ◽  
Angular Motion ◽  
Analytical Relationship ◽  
Load Bearing ◽  
Behavioral Studies ◽  
Contact Surfaces

Abstract In this study we developed an analytical relationship between adhesive digit orientation and adhesive force capacity to describe the tendencies of climbing organisms that use adhesion for climbing to align their toes in the direction of loading, maximizing adhesive force capacity. We fabricated a multi-component adhesive device with multiple contact surfaces, or digits, to act as a model system mimicking the angular motion of a foot and found the synthetic experiments agree with the developed analytical relationship. In turn, we find that observations of gekkonid lizards climbing on vertical substrates correlate well with our analytical relationship; a reduction in toe spacing is seen on the forelimbs when the animals are facing up. Interestingly, the toes on the hindlimbs tend to have an increase in spacing, possibly a mechanism for stabilization rather than load-bearing.

A Dynamic Contact Model of Rough Surfaces Based on the Microscopic Contact Analysis of Asperities

2013 ◽  
Vol 785-786 ◽  
pp. 1208-1211
Author(s):  
Yan Qing Tan ◽  
Lian Hong Zhang ◽  
Ya Hui Hu
Keyword(s):  
Surface Topography ◽  
Rough Surfaces ◽  
Dynamic Contact ◽  
Contact Model ◽  
Fatigue Wear ◽  
Contact Parameter ◽  
Wear Process ◽  
Static Contact ◽  
Contact Models ◽  
Set Up

Dynamic contact model of rough surfaces can provide the theoretical basis for analyzing the microscopic damage of surfaces in wear process and constructing the analytical wear model to predict wear. A dynamic contact model of sliding rough surfaces is innovatively constructed based on the characterization of the contact asperities on rough surfaces in this paper. Firstly, an asperity model of rough surface is set up according to the surface topography parameters and the static contact parameters is evaluated in the light of statistics contact theory; Then the contact characteristic of surface topography in sliding is analyzed and a series of equivalent contact models are proposed; Finally, the dynamic contact model of rough surfaces is established and from which the dynamic contact parameter of rough surfaces is formulated. The dynamic contact model can be further improved to analyze the friction fatigue wear of sliding pairs and provide reference for tribology design of mechanical surfaces.

Friction Damping of Interlocked Vane Segments: Experimental Results

2001 ◽  
Author(s):  
T. Berruti ◽  
S. Filippi ◽  
M. M. Gola ◽  
S. Salvano
Keyword(s):  
Numerical Analysis ◽  
Energy Dissipation ◽  
Contact Surface ◽  
Aircraft Engine ◽  
Experimental Methods ◽  
Experimental Results ◽  
Contact Model ◽  
Friction Damping ◽  
Contact Surfaces ◽  
Adjacent Segments

Experimental methods and results of the stator bladed segment of an aircraft engine are presented. Investigation concern the energy dissipation due to friction between contact surfaces of adjacent segments. The influence of the force normal to the contact surface (due to interference between adjacent segments) on friction damping is shown. Moreover the experiments show the nature of friction at contact surfaces. The parameters of a contact model to be used in a numerical analysis have been identified from the experiments.

An Improved Fast Algorithm of Spacecraft Separation Distance Calculation

2013 ◽  
Vol 774-776 ◽  
pp. 1560-1566
Author(s):  
Zi Long Hao ◽  
Xin Jian Liu
Keyword(s):  
Fast Algorithm ◽  
Simulation Analysis ◽  
Separation Distance ◽  
Separation Process ◽  
Distance Calculation ◽  
Shortest Distance ◽  
Spatial Bodies

A faster algorithm for calculating the shortest distance between two spatial bodies based on existing algorithms was presented. A simulation analysis of missile models separation process was built by using this algorithm. The simulation proved that this algorithm has the same precision and faster speed compared with other existing algorithms.

A simple expression for fluid inertia force acting on micro-plates undergoing squeeze film damping

2010 ◽  
Vol 467 (2126) ◽  
pp. 522-536 ◽  
Author(s):  
Shujuan Huang ◽  
Diana-Andra Borca-Tasciuc ◽  
John A. Tichy
Keyword(s):  
Separation Distance ◽  
Simple Expression ◽  
Squeeze Film ◽  
Inertia Force ◽  
Viscous Damping ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Viscous Forces ◽  
Squeeze Film Damping ◽  
Micro Plates

Squeeze film damping in systems employing micro-plates parallel to a substrate and undergoing small normal vibrations is theoretically investigated. In high-density fluids, inertia forces may play a significant role affecting the dynamic response of such systems. Previous models of squeeze film damping taking inertia into account do not clearly isolate this effect from viscous damping. Therefore, currently, there is no simple way to distinguish between these two hydrodynamic effects. This paper presents a simple solution for the hydrodynamic force acting on a plate vibrating in an incompressible fluid, with distinctive terms describing inertia and viscous damping. Similar to the damping constant describing viscous losses, an inertia constant, given by ρL 3 W / h (where ρ is fluid density, L and W are plate length and width, respectively, and h is separation distance), may be used to accurately calculate fluid inertia for small oscillation Reynolds numbers. In contrast with viscous forces that suppress the amplitude of the oscillation, it is found that fluid inertia acts as an added mass, shifting the natural frequency of the system to a lower range while having little effect on the amplitude. Dimensionless parameters describing the relative importance of viscous and inertia effects also emerge from the analysis.

Friction Damping of Interlocked Vane Segments: Experimental Results

2002 ◽  
Vol 124 (4) ◽  
pp. 1018-1024 ◽  
Author(s):  
T. Berruti ◽  
S. Filippi ◽  
M. M. Gola ◽  
S. Salvano
Keyword(s):  
Numerical Analysis ◽  
Energy Dissipation ◽  
Contact Surface ◽  
Aircraft Engine ◽  
Experimental Methods ◽  
Experimental Results ◽  
Contact Model ◽  
Friction Damping ◽  
Contact Surfaces ◽  
Adjacent Segments

Experimental methods and results of the stator bladed segment of an aircraft engine are presented. Investigation concerns the energy dissipation due to friction between contact surfaces of adjacent segments. The influence of the force normal to the contact surface (due to interference between adjacent segments) on friction damping is shown. Moreover, the experiments show the nature of friction at contact surfaces. The parameters of a contact model to be used in a numerical analysis have been identified from the experiments.

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