Three-Dimensional Adhesive Contact Analysis for Surfaces with a Simplified Surface Roughness using van der Waals Force

2018 ◽  
Vol 2018 (0) ◽  
pp. J0470401
Author(s):  
Hideo KOGUCHI
Keyword(s):  
Surface Roughness ◽  
Van Der Waals ◽  
Three Dimensional ◽  
Adhesive Contact ◽  
Contact Analysis ◽  
Van Der Waals Force

Boundary Element Analysis of Adhesion Considering van der Waals Force

2013 ◽  
Author(s):  
Hideo Koguchi ◽  
Kyohei Seki
Keyword(s):  
Microelectromechanical Systems ◽  
Van Der Waals ◽  
Nonlinear Function ◽  
Adhesive Contact ◽  
Simultaneous Equation ◽  
Boundary Integral ◽  
Van Der Waals Force ◽  
Boundary Integral Method ◽  
Element Analysis ◽  
Stick Slip

Recently, micro- and nano-machine for microelectromechanical systems (MEMS) and the mechanism of bio-adhesive pads and sensors attract great interest. Forces such as the van der Waals force affect the adhesion in nanoscale structures. Even if two bodies does not really contact, adhesion will happen as they approach each other. The adhesion occurs easily in micromachines, so several devices are required to prevent the adhesion. In the present paper, the van der Waals force is introduced into a boundary integral method (BEM) program for analyzing the adhesion in arbitrarily shaped bodies. The van der Waals force is described by a nonlinear function of the distance between two surfaces in close proximity, and the adhesion and repulsion forces vary greatly within the atom equilibrium distance, so the solution for the simultaneous equation in the BEM is hard to converge to an exact solution. In the present paper, we propose a method for converging to a solution, apply it to the adhesion problem between a cylinder and a flat substrate, and compare the solution with the previously published theoretical result. Furthermore, adhesive contact of a semicircular cylinder and a half domain with a wavy surface is analyzed, and the semicircular cylinder is moved to the horizontal direction of the domain. Then, stick-slip phenomenon can be observed and a variation of friction coefficient is discussed. In our analysis, a repeated boundary condition is introduced like a molecular dynamics analysis. So, the program can be used for evaluating the adhesion in a large system.

van der Waals force layered multiferroic hybrid perovskite (CH3NH3)2CuCl4 single crystals

2020 ◽  
Vol 22 (7) ◽  
pp. 4235-4239
Author(s):  
Zhao Hu ◽  
Hongyang Zhao ◽  
Zhenxiang Cheng ◽  
Jianxu Ding ◽  
Han Gao ◽  
...  
Keyword(s):  
Single Crystals ◽  
Van Der Waals ◽  
Three Dimensional ◽  
Van Der Waals Force ◽  
Organic Group ◽  
Hybrid Perovskite

In inorganic–organic perovskites, the three-dimensional arrangement of the organic group results in more subtle balance of charge, spin and space, thereby providing an attractive route toward new multiferroics.

Investigations of the Adhesive Contact Behavior of Elastic Layered Media With Surface Roughness

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Yuyan Zhang ◽  
Lina Si ◽  
Xiaoqing Zhang ◽  
Juan Li ◽  
Wanjun Wang
Keyword(s):  
Surface Roughness ◽  
Layered Medium ◽  
Three Dimensional ◽  
Homogeneous Medium ◽  
Surface Force ◽  
Adhesive Contact ◽  
Diamond Like Carbon ◽  
Contact Behavior ◽  
Average Value ◽  
Homogeneous Half Space

A deterministic adhesive model for the contact between an elastic layered medium with surface roughness and a smooth elastic microsphere was developed on the basis of the Lennard–Jones surface force law. Through numerical simulations, the adhesive contact behavior of the layered medium with the measured three-dimensional (3D) surface topography was comparatively analyzed with that of the homogeneous medium. Furthermore, the contact characteristics of the layered medium with pre-assigned roughness parameters were investigated with the aid of a computer-generated technique for simulating surface roughness. Results showed that the pull-off force for the contact problem involving rough surfaces was influenced by the contact location, and the average value for the contact between an alumina (SiO2) microsphere and a diamond-like carbon/silicon (DLC/Si)-layered medium was smaller than that for the contact between a SiO2 microsphere and a Si homogeneous half-space. In addition, the effect of the diamond-like carbon (DLC) layer on reducing adhesion was smaller than that of the surface roughness. Finally, the average pull-off force for a DLC/Si-layered medium with computer-generated surface roughness rapidly decreased; however, it eventually became almost unchangeable with the increase in the root-mean-square (RMS) deviation.

Discussion on the Relation between the Adhesive Force of Drosophila Melanogaster and the Surface Roughness of the Substrate

2012 ◽  
Vol 159 ◽  
pp. 93-98
Author(s):  
Rui Guo Cui ◽  
Wei Dong Yu
Keyword(s):  
Surface Roughness ◽  
Drosophila Melanogaster ◽  
Van Der Waals ◽  
Adhesive Force ◽  
Van Der Waals Force ◽  
Basic Form ◽  
Adhesive Pads ◽  
R Value ◽  
Friction Plate ◽  
Gripping Force

Three forms of animals’ adhesion were analyzed: hairy adhesive pads, smooth adhesive pads and claw. Scanning electron microscope (SEM) was used to observe the surface of friction plate with different particle diameters. It’s found that the particle could be seen as conical shape. The self-designed lever-like testing equipment was also used to measure the adhesive force of drosophila melanogaster contacting 6 substrates with different roughness. It was shown that adhesive force decreased first and finally rose with the increase of surface roughness. When the roughness (R value) was about 68.5nm, it showed that the lowest adhesive force was 0.0085mN. Then model of the Van der Waals force was established. In this model, contact form between seta and the substrate was divided into five states, and the theoretical adhesive force at each state was calculated, which successfully simulated with the actual value. However, when surface roughness reached the situation that the gap between adjacent particles was greater than 2μm, the gripping function of the claw made the actual value greater than theoretical one. It was concluded that adhesive force was a compound function of the Van der Waals force generated by hairy adhesive force and the gripping force generated by claw. So it was also speculated that the fibrous fine pads of insects were the basic form adhesion on smooth surface of the substrate.

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