Study on the influence of atomic distance change on frictional force

2018 ◽  
Vol 2018.9 (0) ◽  
pp. 30am3PN1
Author(s):  
Shu Kimura ◽  
Yasuhisa Ando
Keyword(s):  
Frictional Force ◽  
Atomic Distance ◽  
Distance Change

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

Peristaltic flow of a Jeffery fluid over a porous conduit in the presence of variable liquid properties and convective boundary conditions

2019 ◽  
Vol 6 (2) ◽  
Author(s):  
G. Manjunatha ◽  
C. Rajashekhar ◽  
K. V. Prasad ◽  
Hanumesh Vaidya ◽  
Saraswati
Keyword(s):  
Boundary Conditions ◽  
Frictional Force ◽  
Variable Viscosity ◽  
Pressure Rise ◽  
Velocity Slip ◽  
Peristaltic Flow ◽  
Physical Parameters ◽  
Convective Boundary Conditions ◽  
Convective Boundary ◽  
Closed Form Solutions

The present article addresses the peristaltic flow of a Jeffery fluid over an inclined axisymmetric porous tube with varying viscosity and thermal conductivity. Velocity slip and convective boundary conditions are considered. Resulting governing equations are solved using long wavelength and small Reynolds number approximations. The closed-form solutions are obtained for velocity, streamline, pressure gradient, temperature, pressure rise, and frictional force. The MATLAB numerical simulations are utilized to compute pressure rise and frictional force. The impacts of various physical parameters in the interims for time-averaged flow rate with pressure rise and is examined. The consequences of sinusoidal, multi-sinusoidal, triangular, trapezoidal, and square waveforms on physiological parameters are analyzed and discussed through graphs. The analysis reveals that the presence of variable viscosity helps in controlling the pumping performance of the fluid.

Electromagnetic-matter interactions and devices

2017 ◽  
Author(s):  
Sandip Tiwari
Keyword(s):  
Optical Tweezers ◽  
Quantum Cascade Lasers ◽  
Accelerator Physics ◽  
X Ray ◽  
Quantum Cascade ◽  
Inorganic Systems ◽  
Charge Cloud ◽  
Atomic Distance ◽  
Extinction Length ◽  
Cascade Lasers

This chapter explores electromagnetic-matter interactions from photon to extinction length scales, i.e., nanometer of X-ray and above. Starting with Casimir-Polder effect to understand interactions of metals and dielectrics at near-atomic distance scale, it stretches to larger wavelengths to explore optomechanics and its ability for energy exchange and signal transduction between PHz and GHz. This range is explored with near-quantum sensitivity limits. The chapter also develops the understanding phononic bandgaps, and for photons, it explores the use of energetic coupling for useful devices such as optical tweezers, confocal microscopes and atomic clocks. It also explores miniature accelerators as a frontier area in accelerator physics. Plasmonics—the electromagnetic interaction with electron charge cloud—is explored for propagating and confined conditions together with the approaches’ possible uses. Optoelectronic energy conversion is analyzed in organic and inorganic systems, with their underlying interaction physics through solar cells and its thermodynamic limit, and quantum cascade lasers.

Experimental study on the factors affecting squeak noise occurrence in automotive suspension bushings

2021 ◽  
pp. 095440702110241
Author(s):  
Byunghyun Kang ◽  
Cheol Choi ◽  
Daeun Sung ◽  
Seongho Yoon ◽  
Byoung-Ho Choi
Keyword(s):  
Neural Network ◽  
Logistic Regression ◽  
Influencing Factors ◽  
Frictional Force ◽  
Prediction Models ◽  
Statistical Tests ◽  
Network Models ◽  
Multiple Logistic Regression ◽  
Neural Network Models ◽  
Automotive Suspension

In this study, friction tests are performed, via a custom-built friction tester, on specimens of natural rubber used in automotive suspension bushings. By analyzing the problematic suspension bushings, the eleven candidate factors that influence squeak noise are selected: surface lubrication, hardness, vulcanization condition, surface texture, additive content, sample thickness, thermal aging, temperature, surface moisture, friction speed, and normal force. Through friction tests, the changes are investigated in frictional force and squeak noise occurrence according to various levels of the influencing factors. The degree of correlation between frictional force and squeak noise occurrence with the factors is determined through statistical tests, and the relationship between frictional force and squeak noise occurrence based on the test results is discussed. Squeak noise prediction models are constructed by considering the interactions among the influencing factors through both multiple logistic regression and neural network analysis. The accuracies of the two prediction models are evaluated by comparing predicted and measured results. The accuracies of the multiple logistic regression and neural network models in predicting the occurrence of squeak noise are 88.2% and 87.2%, respectively.

Frictional force apparatus

1976 ◽  
Vol 14 (6) ◽  
pp. 373-374
Author(s):  
Terril W. Mayes
Keyword(s):  
Frictional Force

Band Brake Squeal

1996 ◽  
Vol 118 (2) ◽  
pp. 190-197 ◽  
Author(s):  
M. Nakai ◽  
M. Yokoi
Keyword(s):  
Elastic Foundation ◽  
Frictional Force ◽  
Linear Analysis ◽  
Brake Squeal ◽  
Constant Frequency ◽  
Squeal Noise ◽  
Effective Treatments

The purpose of this paper is to investigate the squealing mechanism of band brakes in order to develop effective treatments for the reduction or elimination of squeal noise. With increasing rotational drum speed, squeal frequency increases up to a constant frequency. This constant squeal frequency coincides precisely with the frequency of instability obtained by a linear analysis of the motion of a band on an elastic foundation when the frictional force between the lining of the band and the drum is taken into account. Through experiments and analyses, it will be demonstrated that squeals are induced by the coupling between two modes of the band.

PERISTALTIC FLOW OF COUPLE-STRESS CONDUCTING FLUIDS THROUGH A POROUS CHANNEL: APPLICATIONS TO BLOOD FLOW IN THE MICRO-CIRCULATORY SYSTEM

2011 ◽  
Vol 19 (03) ◽  
pp. 461-477 ◽  
Author(s):  
DHARMENDRA TRIPATHI
Keyword(s):  
Frictional Force ◽  
Couple Stress ◽  
Amplitude Ratio ◽  
Circulatory System ◽  
Mechanical Efficiency ◽  
Peristaltic Flow ◽  
Porous Channel ◽  
Stress Parameter ◽  
Permeability Parameter ◽  
Conducting Fluids

The present investigation is devoted to study a theoretical investigation of the peristaltic flow of a couple-stress conducting fluids in a porous channel under the influence of slip boundary condition. This study is applicable to the physiological flow of blood in the micro-circulatory system, by taking account of the particle size effect. The expressions for axial velocity, pressure gradient, stream function, frictional force and mechanical efficiency are obtained under the small Reynolds number and the large wavelength approximations. Effects of different physical parameters reflecting permeability parameter, couple-stress parameter, Hartmann number as well as amplitude ratio on pumping characteristics, frictional force, mechanical efficiency and trapping of peristaltic flow pattern are studied. The computational and numerical results are presented in graphical form. On the basis of our discussion, it is concluded that pressure reduces by increasing the magnitude of couple-stress parameter, permeability parameter, slip parameter, whereas it enhances by increasing the magnitude of magnetic field and amplitude ratio.

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