Fractal analysis of eroded surfaces by digital image processing (original) (raw)
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physica status solidi (b), 2012
Optical and scanning electron microscopy (OM and SEM) are techniques that are normally used for 2D-analysis of surface features. By fractal dimension analysis of the gray-scale OM and SEM images, it is possible to get quantitative topographical measurements. In this work, three different surface topographies (polished, eroded, and oxidized) were analyzed on FeCrAl alloy by OM and SEM. Clear surface topographical changes can be qualitatively observed. In order to quantify such changes, two steps were followed: (i) a gray-scale digitalization from each image was used to reproduce topographical features on the analyzed surface, and (ii) from this information, the fractal dimension (D) was determined using fractal3e software. The fractal dimension determined in this form follows coherently the topographical changes produced on the FeCrAl alloy after polishing, erosion, and oxidizing processes. The variations of fractal dimension values against the temperature of the oxidizing processes reflect well the oxide growth changes. Moreover, a minimum D-value is registered at 750 8C, which corresponds to the d-u alumina phase transition temperature as determined by differential thermal analysis (DTA) on the same alloy.
Fractal Approach for Erodated Wear of Surfaces by Solide Particles
2014
The goal of this study was to examine the micro-geometry of eroded surfaces of a helicopter blade segment, on the second and third compressor stage, and on a carbon fiber woven composite sample, as resulted from the impact with sand particles. By recording of the roughness height using a spherical head stylus, the Abbott-Firestone bearing curve has been plotted. The random nature of the roughness height is described through statistical analysis. It was found that the distribution frequency follows Weibull’s law. By using the structured function, the fractal nature of the micro-geometry of the eroded surface, the Weierstrass – Mandelbrot (WM) function was determined.
Fractal Characterisation of Worn Surfaces
Tribological behaviour – friction, wear and lubrication – of machine elements highly depend on the operating state and also the original topography of working pair. In our study wear experiments and surface roughness measurements before and after wear were performed. Investigations extended to wear in the course of the non-lubricated ceramic-steel, ferrodo-steel and bronze-steel material pairs. Fractal dimension of topographies before and after wear were calculated using power spectral density, height-difference correlation and scale-analysis methods. The aim of this study was to compare the capability of three different surface characterisation techniques through the analysis of worn surfaces and also to examine the changes of fractal character of topographies in wear.
Comparison of fractal and profilometric methods for surface topography characterization
Applied Surface Science, 2008
In this study microstructural and roughness characterization of surface of aluminium foils used in lithographic printing process was performed by contact and non-contact profilometric methods and fractal analysis. Significant differences in roughness parameters values inferred from stylus method in respect to those inferred from the non-contact measurements were observed. The investigation of correlation between various fractal dimensions obtained from gray-scale SEM micrographs and binary images resulting from median filtering of the original SEM micrographs as well as selected relevant roughness parameters shows that there is a strong correlation between certain roughness parameters and particular fractal dimensions. This correlations permit better physical understanding of fractal characteristics and interpretation of the dynamics of surface roughness change through processing. Generally these correlations are more suitable for parameters obtained by stylus method than those inferred from the laser-based measurements. #
On the description of the fractal nature of microstructured surfaces of titanium implants
Materials Science and Engineering: C, 2003
The determination of the fractal dimension is an interesting way for the characterization of rough surfaces. Microstructured titanium surfaces produced by different technologies (polishing, glass and corundum blasting, vacuum plasma spraying) were investigated by a number of physical and electrochemical methods, i.e. surface profiling, scanning electron microscopy, voltammetry and electrochemical impedance spectroscopy. The data sets obtained by these very different methods were used for the estimation of the fractal dimension of all structures. The aim of this work is to examine the suitability of this additional parameter for a better characterization of structured surfaces and to compare the various applied methods regarding their feasibility. Accompanying cell biological examinations were used to verify whether there is a relation between the parameter fractal dimension and cell behaviour. D
Fractal characterization of fractured surfaces
Acta Metallurgica, 1987
It has recently been claimed [B. B. Mandelbrot, D. E. Passoja and A. J. Pullay, Nature 308, 721 (1984)] that fractured surfaces are fractal in nature, i.e. "self similar" over a wide range of scale and that the fractal dimensions of the surfaces correlate well with the toughness of the material. We have investigated these concepts be measuring the fractal dimensions of fractured surfaces of two titanium alloys and attempting to correlate them with dynamic tear energy. We find that, although fractured surfaces can be classified as approximately fractal, the previous conclusions were too optimistic. An approximate correlation between fractal dimension and dynamic tear energy is obtained. R&sum&--II a Bt& r&cemment avan& [B. B. Mandelbrot, D. E. Passoja et A. J. Pullay, Nature 308, 721 (1984)] que les surfaces de rupture sont de nature fractale, c'est-&dire "autosimilaires" sur une vaste Bchelle et que les dimensions fractales de la surface correspondent bien au durcissement du mat&au. Nous avons ttudit ces concepts en mesurant les dimensions fractales des surfaces de rupture de deux alliages de titane et en essayant de les corrkler avec l'energie dynamique d'arrachement. Nous trouvons que, bien que l'on puisse donner aux surfaces de rupture un caracttre fractal approcht, les conclusions pr&dentes itaient trop optimistes. Nous obtenons une corrtlation approchee entre la dimension fractale et l'energie dynamique d'arrachement. Zusammenfassung-Vor kurzem wurde behauptet [B. B. Mandelbrot, D. E. Passoja und A. J. Pullay, Nature 308, 721 (1984)], daO Bruchfllchen fraktales Verhalten aufweisen, d.h. da13 sie iiber einen weiten MaDstabsbereich 'selbst-iihnlich' sind und dal3 die fraktalen Dimensionen der OberflHche gut mit der ZIhigkeit des Materiales korrelieren. Wir haben diese Konzepte iiberpriift, indem wir die fraktalen Dimensionen der BruchflIchen zweier Titanlegierungen gemessen haben und die Ergebnisse versuchsweise mit der Energie des dynamischen ZerreiDens korreliert haben. Wir finden, daB die friiheren Schliisse zu optimistisch waren, wenngleich Bruchfl&hen als niherungsweise fraktal klassifiziert werden kiinnen. Es ergibt sich eine nzherungsweise Korrelation zwischen fraktaler Dimension und der Energie des dynamischen ZerreiDens.
The application of fractal analysis to the description of brushed steel surfaces
Journal of Machine Engineering, 2020
The notion of fractals and the possibility of exploiting them in surface engineering are discussed. The fractal dimension problem is addressed and basic information relating to brushing and roughness parameters is provided. The results of tests on specimens in the form of structural steel (S275J0) plates subjected to brushing are presented. The machining was conducted using an FWD 32J milling machine with a GE 950 G PLUS straight grinder together with an A11-CB15M brush mounted on it. On the basis of the test results an analysis of selected roughness parameters, with the focus on the different degrees of correlation between the particular indicators and the fractal dimension, was carried out.
Quantitative Analysis of Brittle Fracture Surfaces Using Fractal Geometry
Fractal geometry is a non-Euclidean geometry which has been developed to analyze irregular or fractional shapes. In this paper, fracture in ceramic materials is analyzed as a fractal process. This means that fracture is viewed as a selfsimilar process. We have examined the fracture surfaces of six different alumina materials and five glass-ceramics, with different microstructures, to test for fractal behavior. Slit island analysis and Fourier transform methods were used to determine the fractal dimension, D, of successively sectioned fracture surfaces. We found a correlation between increasing the fractional part of the fractal dimension and increasing toughness. In other words, as the toughness increases, the fracture surface increases in roughness. However, more than just a measure of roughness, the applicability of fractal geometry to fracture implies a mechanism for generation of the fracture surface. The results presented here imply that brittle fracture is a fractal process; this means that we should be able to determine processes on the atomic scale by observing the macroscopic scale by finding the generator shape and the scheme for generation inherent in the fractal process. [
Characterization of the surface topography of arc-treated aluminum alloys by fractal geometry
Manufacturing Letters, 2014
An atmospheric pressure plasma arc discharge creates a complex structure on an aluminum (Al) surface that is a challenging task to characterize by conventional techniques. The solution could be in applying the principles of fractal geometry to characterize the arc-treated aluminum surface while studying profiles obtained by an optical profilometer and SEM (scanning electron microscope) images. The fractal dimension (FD) is determined along with the other conventional surface characteristic parameters (R a , R q , S a , and S q). The influence of the arc process parameters such as the arc current (I) and plasma torch velocity (v) on the fractal dimension is explored.