Acta Stereologica Acta Stereologica -  Volume 13 (1994)  Number 1 - Proceedings of the sixth European congress for stereology - Part two - May 1994 

Use of the Fourier transform for composite materials quality controls by image processing

Stéphane Bres
LISPI, Equipe de Reconnaissance de Formes et Diagnostic, I.N.S.A. Bat 403, 20, Avenue A. Einstein 69621 Villeurbanne Cedex, France
Gérard Merle
Laboratoire des Matériaux Macromoléculaires, I.N.S.A. Bat 403, 20, Avenue A. Einstein 69621 Villeurbanne Cedex, France
Hubert Emptoz
LISPI, Equipe de Reconnaissance de Formes et Diagnostic, I.N.S.A. Bat 403, 20, Avenue A. Einstein 69621 Villeurbanne Cedex, France

Abstract

A piece in composite material consists of a glass fibre reinforcement imbedded in a matrix. Most of the characteristics of the piece depend on two main factors: the impregnation quality of these glass fibres by a resin and the distribution of their directions in the final piece.

The first part of this paper presents two methods that give a quantitative evaluation of the impregnation evolution of glass fibres by a resin during the fabrication of the piece. A treatment based on the mean grey level value of each image gives a first method of impregnation evaluation. A second possible treatment uses a test pattern underneath the composite material during the fabrication of the piece. The evaluation of the impregnation rate is based on the calculus of auto correlation or cross correlation functions.

The second part of this paper is dedicated to the calculus of a rose of directions on an image in grey levels. This rose is based on the analysis of the image in the spectral domain i.e. on the Fourier transform of the image. This is a very useful tool, and not only for quality controls on composite materials.

Keywords : composite materials, Fourier transform, image processing, quality control, rose of directions

To cite this article

Stéphane Bres, Gérard Merle & Hubert Emptoz, «Use of the Fourier transform for composite materials quality controls by image processing», Acta Stereologica [En ligne], Volume 13 (1994), Number 1 - Proceedings of the sixth European congress for stereology - Part two - May 1994, 237-242 URL : https://popups.ulg.ac.be/0351-580x/index.php?id=4657.