Computerized photoelastic fringe multiplication

Abstract

In photoelasticity, by employing the standard circular light- and dark-field procedures, isochromatic fringe values of integrand half order can be obtained. However, it is desirable to improve the accuracy of the fractional fringe orders. Several compensation techniques are employed, but these are point-by-point techniques which can be very tedious and time consuming. Post developed a fringe-multiplication technique which is full-field, but being a lens polariscope, it requires additional accessory equipment. This paper presents another method of fringe multiplication which essentially employs the concept of superimposing the light- and dark-field isochromatic fringe patterns using an image-processing technique. This is done by subtracting the pixel intensities of the dark-field image from the light-field image. There is no need for films and dark-room facilities. The VICOM image-processing system is used here. Basically, this system is a minicomputer with image-processing software.