A COMPARATIVE STUDY OF PHOTOELASTIC METHODS FOR S.I.F. DETERMINATION

Abstract

Five photoelastic. methods viz Irwin, Bradley Kobayashi, Smith, Maximum Isochromatic width and Three Parameter, have been used for determination of Stress Intensity Factors. Five specimen type viz. Side Edge Notched, Disc type, C-specimen, Central surface cracked tension panel and through thickness crack specimen. Five different crack length to width ratio have been examined for each type of specimens. These ratios are then kept almost constant for different specimens, Both the geometrical variations of isochromatic fringe loop geometry and SIP estimates were determined using stress frozen photoelastic technique. Results by different methods show a little variation : Al], the methods give fairly good results when a' sharp.fringe close to the crack tip is available. When the density of isochromatic fringes is high near the crack tip then the Bradley and Kobayashi and three parameter method give better .results making use of distant fringe-loops. Different methods have been compared and discussed.