PHOTOELASTIC DETERMINATION OF CRACK EXTENSION DIRECTION

Abstract

The objective of the present work is to study the effect of specimen geometry on the angle at which a crack would propagate under mixed mode loading condition. The edge and centre cracked specimen made from epoxy resin have been considered for each type of specimen. The crack extension direction have been determined photoelastically from the analysis of isochromatic fringe loops. Experimental results are presented to determine, mode I and mode II stress intensity factors through coordinate measurements of the maximum radius and corresponding fringe tilt angle e of an m Apogee point on an isochromatic fringe loop. The results have been analysed using Smith's approach. Crack extension direction are determined by using Sih's criterion. The experimental results are presented in graphical and tabular forms and the, logical conclusion about the effect of specimen geometry on the crack extension direction are drawn. The experimental results show that the crack extension direction decreases as crack, -length and inclination increases. The effect of crack inclination on the crack extension direction is much more than the effect of crack length. It is also observed that the edge crack is more severe than the centre crack.