الفهرس Only 14 pages are availabe for public view
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Abstract
Surface texture is considered as one of the main factors affecting the performance characteristics of engineering products. The mechanical characteristics such as fatigue life, wear, and load carrying capacity besides physical properties such as conductivity and reflectivity are examples of the product properties affected by surface texture. Surface texture can be evaluated by several techniques including mechanical, pneumatic, and 0 ptical methods. 0 ptical methods have several advantages such as; being noncontact and fast. Optical methods can also be applied for in-process and on¬line inspection. Moreover, it is possible to integrate an optical inspection system into a computer aided manufacturing system.
The present study proposes an optical method for surface roughness assessment using Morphological Image Processing (MIP). A flat engineering surface 0 bserved under appropriate illumination will exhibit a specific morphology depicted in the form of a pattern of bright and dark (shadow) areas. This recorded optical morphology will be unique for each surface and depend on the type and dimension of surface roughness irregularities. When a surface with uniform straight lay (e.g. shaped) is correctly illuminated it will give rise to a stripe-line shadow pattern (morphology). The average width of the shadow bands will depend on factors such as; roughness amplitude, roughness wavelength, type and direction of illumination, ... etc.
This study is an attempt to establish a relationship between the average shadow width observed when an engineering surface having a straight lay texture is illuminated with a collimated beam of light and surface texture parameters such as amplitude and wavelength.
An analytical analysis is carried out on a surface roughness model presented by a Fourier Series (FS) to study the effect of illumination angle in accordance with the roughness model on the resultant shadow width.
The analysis is then applied on a set of assumed roughness irregularities forms namely; triangular, sinusoidal, circular, and inverted circular. The analytical analysis shows how the shadow width is affected by the form and dimensions of irregularities and the light incidence angle. The study shows that the shadow width as a measure for surface morphology can be correlated to the surface roughness amplitude and wavelength parameters. To verify the analytical analysis, the study is then applied on a set of specimens produced with unidirectional surface texture as well as standard specimens. The manufactured specimens were produced by shaping using variable feed rate and tool angle to obtain roughness forms of different amplitudes and wavelengths .
Images of the test surfaces were recorded and analyzed using Morphological Image Processing (MIP) approach. A special set-up was prepared to illuminate and image the tested surfaces. The set-up had the facility to change and measure the illumination
angle.
The experimental work showed that the average shadow width can be used as an
indication to the variation in the surface roughness parameters, for the case considered
in the study.
The study further considers the use of the resultant shadow width at specific
illumination angles as a method to reconstruct surface texture irregularities profile form. The results show a good agreement betWeen the actual roughness profile and
the reconstructed one.