Counterface Roughness Effect on the Dry Steady State Wear of Self-Lubricating Polyimide Composites

1984 ◽  
Vol 106 (2) ◽  
pp. 177-184 ◽  
Author(s):  
D. F. Play
Keyword(s):  
Fourier Transform ◽  
Steady State ◽  
Friction And Wear ◽  
Unit Length ◽  
Wave Length ◽  
Statistical Data Analysis ◽  
Wear Rates ◽  
Polyimide Composites ◽  
The Fourier Transform ◽  
Counterface Roughness

Initial counterface topography influences both running-in and steady state wear rates of polymers. But governing roughness parameters are difficult to isolate because of their strong dependences and their statistical natures. Distributions of RT, RA, R.M.S., Skewness, Kurtosis, profile slopes, number of peaks per unit length, radii of curvature of peak asperity and Fourier transform were considered to characterize the isotropic roughness of the abraded steel disks. Two polyimide composites with PTFE and CF x powders were chosen for the pins. Correlations between parameters, friction and linear steady state wear were obtained through statistical data analysis. Radii of curvature, profile slopes or RA, and number of peaks govern friction and wear in different ways depending on fillers. However, for both materials, wear increases with average slopes or RA and decreases with an increase of number of peaks and radii of curvature. Skewness governs also the results but Kurtosis and wave length of the maximum of the Fourier transform are useless to explain the results.

A transient technique for seismograph calibration

1962 ◽  
Vol 52 (4) ◽  
pp. 767-779
Author(s):  
A. F. Espinosa ◽  
G. H. Sutton ◽  
H. J. Miller
Keyword(s):  
Fourier Transform ◽  
Steady State ◽  
Input Pulse ◽  
Electrical Signal ◽  
Experimental Results ◽  
Response Curves ◽  
Amplitude Response ◽  
Transient Technique ◽  
Absolute Amplitude ◽  
The Fourier Transform

abstract A transient technique for seismograph calibration was developed and tested by a variety of methods. In the application of this technique a known transient in the form of an electrical signal is injected, through (a) a Willmore-type calibration bridge or (b) an independent coil, into the seismometer and the corresponding output transient of the system is recorded. The ratio of the Fourier transform of this transient to that of the input pulse yields phase and relative amplitude response of the seismograph as a function of period. Absolute amplitude response may be calculated if two easily determined constants of the seismometer are known. This technique makes practical the daily calibration of continuously-recording seismographs without disturbing the instruments more than a very few minutes. The transient technique was tested and proven satisfactory with results of more conventional steady-state methods, using both digital and analog analyses of the output transients. A variety of output transients corresponding to various theoretical response curves has been calculated for two standard input transients. By comparison of the calculated output transients with experimental results it is possible to obtain the response of the instrument with considerable precision quickly and without computation.

The Effect of Tribofilm Formation and Humidity on the Friction and Wear Properties of Ceramic Materials

1992 ◽  
Vol 114 (1) ◽  
pp. 131-140 ◽  
Author(s):  
K. Komvopoulos ◽  
H. Li
Keyword(s):  
Steady State ◽  
Wear Debris ◽  
Friction And Wear ◽  
Ceramic Materials ◽  
Composition Analysis ◽  
Wear Properties ◽  
Qualitative Comparison ◽  
Wear Rates ◽  
Subsurface Material ◽  
Friction And Wear Properties

The processes of tribofilm formation and disruption and the predominant tribo-mechanisms of unlubricated ceramic materials were investigated experimentally. Sliding experiments in humidity controlled atmospheres revealed that the formation of interfacial tribofilms significantly affects the steady-state friction and wear properties of ceramics. Scanning electron microscopy and various composition analysis techniques demonstrated that although tribochemical reactions might occur, the principal mechanisms of tribofilm formation were the generation, agglomeration, and compaction of fine wear debris produced from both sliding surfaces. The tribofilms exhibited different tribological characteristics, depending on their elemental compositions and the humidity. For all the ceramic pairs tested, the steady-state coefficients of friction decreased with relative humidity. In contrast to the conventional fracture toughness approach, surface profilometry and microscopy studies showed that the highest wear rates were encountered with the toughest ceramic. Plowing grooves parallel to the direction of sliding, fine wear debris of round and cylindrical shapes, microcracking, and localized delamination of the tribofilms were identified. Microscopic observations suggested that damage of the subsurface material adjacent to the interface of the tribofilms was immeasurable. Qualitative comparison of the topographical features of worn surfaces indicated that, depending on the humidity and the type of ceramic, microplasticity, microfracture, and delamination of the tribofilms were the prevailing steady-state tribomechanisms.

Third Body Formation and the Wear of PTFE Fibre-Based Dry Bearings

1980 ◽  
Vol 102 (2) ◽  
pp. 236-245 ◽  
Author(s):  
J. K. Lancaster ◽  
D. Play ◽  
M. Godet ◽  
A. P. Verrall ◽  
R. Waghorne
Keyword(s):  
Photoelectron Spectroscopy ◽  
Friction And Wear ◽  
Resin Composite ◽  
X Rays ◽  
Third Body ◽  
Fibre Glass ◽  
Wear Rates ◽  
The Coefficient Of Friction ◽  
Considerable Degradation ◽  
Counterface Roughness

Dry bearing tests have been made with a PTFE fibre/glass fibre/phenolic resin composite against stainless steel to examine the influence of time of sliding, counterface roughness and load. The worn surfaces were examined by optical and scanning electron microscopy, energy dispersive analysis of X-rays (EDAX) and X-ray photoelectron spectroscopy (ESCA). It is shown that the coefficient of friction and the rate of wear are strongly influenced by the formation of third bodies on both sliding surfaces. The structure and composition of these third bodies depend on the time of sliding and the load, but are independent of counterface roughness. Wear of the PTFE composite appears to occur on several scales, and considerable degradation of PTFE is evident within the third body (transfer film) on the counterface. The significance of these observations to the measured friction and wear rates is discussed.

Eigenvalue Analysis of Identical Ladder Networks

1980 ◽  
Vol 17 (4) ◽  
pp. 359-366 ◽  
Author(s):  
C. S. Indulkar
Keyword(s):  
Fourier Transform ◽  
Steady State ◽  
Short Circuit ◽  
Open Circuit ◽  
Eigenvalue Analysis ◽  
Transform Method ◽  
Fourier Transform Method ◽  
The Fourier Transform

Identical ladder networks with open-circuit, short-circuit, and matched terminations have been analysed using the eigenvalue technique. The technique has been applied to determine the steady-state and transient potential distributions across a string of 400 KV insulators. The latter has been calculated by using this technique and the Fourier transform method.

scholarly journals Stochastic Analysis of an Epidemic SVIR Model With Holling Type II Incidence and Treatment Rates

2021 ◽  
Author(s):  
V Madhusudanan ◽  
M N Srini ◽  
L. Amalraj
Keyword(s):  
Fourier Transform ◽  
Steady State ◽  
Stochastic Stability ◽  
Stochastic Analysis ◽  
Critical Role ◽  
Type Ii ◽  
Inhibitory Effects ◽  
The World ◽  
The Fourier Transform ◽  
Theoretical Results

Abstract In the event of an epidemic, inhibitory effects play a critical role in limiting the pandemic's influence on society. The majority of infectious diseases that affect humans are still on the verge of becoming epidemics over the world. Mathematical models have long been used to investigate the complicated dynamics of infectious illnesses. This research investigates a stochastic SVIR epidemic model with Holling type II incidence and treatment rates. The Fourier transform approach is used to analyse stochastic stability around an internal steady state. Finally, numerical simulations are presented with appropriate parameter selections in order to test the efficiency of the theoretical results.

Methods for Computing 3D Steady-State Vibrations of Composites Using Green’s Functions

2010 ◽  
Author(s):  
Alexander Karmazin ◽  
Evgenia Kirillova ◽  
Wolfgang Seemann ◽  
Pavel Syromyatnikov
Keyword(s):  
Fourier Transform ◽  
Steady State ◽  
Elastic Anisotropy ◽  
Displacement Vector ◽  
Phase Method ◽  
Stationary Phase Method ◽  
Surface Load ◽  
Load Vector ◽  
Green’S Matrix ◽  
The Fourier Transform

Spatial steady-state harmonic vibrations of an infinite layered composite plate with an arbitrary elastic anisotropy of each layer are considered in this paper. The required vector of mechanical displacements of arbitrary points for a layered structure can be represented in the form of a double inverse Fourier transform of the product of the Fourier transform of the Green’s matrix and the Fourier transform of the surface load vector. An algorithm for computing the Fourier inverse transform with the given load vector is presented. Reducing of the initial double integral to the repeated one and using Jordan’s lemma make it possible to present the displacement vector in terms of residues in real and complex poles of the Green’s matrix. The stationary phase method is applied for computing asymptotic representations of the displacement field in the far-field zone. Displacements on the surface of some various composites on the basis of graphite-epoxy material for two types of surface load were computed as numerical examples.

Research of a New Power Quality Detection System Based on ARM

2014 ◽  
Vol 568-570 ◽  
pp. 1825-1833
Author(s):  
Yan Qing Peng ◽  
Feng Wang ◽  
Ji Zhang ◽  
Jia Li ◽  
Da Min Zhang
Keyword(s):  
Fourier Transform ◽  
Wavelet Transform ◽  
Steady State ◽  
Fast Fourier Transform ◽  
Power Quality ◽  
Detection System ◽  
Detection Algorithm ◽  
Detection Algorithms ◽  
Quality Detection ◽  
The Fourier Transform

Based on the comparative analysis of the fast Fourier transform (FFT), the short-time Fourier transform (STFT), the wavelet transform (WT) and other power quality detection algorithms, this paper puts forward to a new power quality detection algorithm which combines the Fourier transform with the wavelet transform. The transient as well as the steady state signals are separated on the basis that the wavelet transform is sensitive to the singular signals. The presented algorithm detects a variety of harmonic parameters of the gird after the separation of steady state signals is finished by fast Fourier transform. A new power quality detection system is then designed based on the core chip of S3C2440A, and the algorithm which is ARM-9 based is transplanted into the embedded Linux operating system to carry out the experiments. Analysis of the experimental data shows the detection algorithm is reliable by Fourier transform and wavelet transform.

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