APPLYING PHOTOELASTICITY WITH OPTICAL MAGNIFICATION METHOD TO INCREASE PRECISION OF DETERMINING FRINGE ORDER UNDER MONOCHROMATIC LIGHT

Photoelasticity method was used to measure strain and stress fields to address the precision problem of determining fringe order of loading and cracking and notch areas. In this study, microscope was used as an additional tool in a photoelastic device for magnification of isochromatic fringe size. An experimental method was used by utilizing optical system and reflective polariscope. A simple compression tool was designed to provide a compression load on the solid disk-shaped specimens. Isochromatic fringe field was observed in the loading zone for different loading and captured image based on the following conditions: 9x, 15x and 20x without magnification and with magnification using SLR type Nikon camera Serie D3000. The image was processed using OpenCV software while C + + was used to produce clearer isochromatic fringe pattern formed on the surface of the specimen in the determination of the maximum fringe order observed. The average of additional fringe could be obtained as the optical magnification result. Data was analyzed using Finite Element Analysis Software. The result showed an increasing trend in fringe order with increasing levels of optical magnification. Its maximum value was obtained on20x optical zoom, which was 2-order fringe.