Stress intensity factors for cracks in C-shaped beam were determined by photoelastic method. Since the nature of corner crack is three-dimensional problem, stress freezing and fringe multiplication technics were employed to measure stress intensity for each slice of specimens.
Photoelastic results of stress intensity factors for surface crack in the thick plate were compared with those obtained by the finite element method, and it showed fairly good agreements.
Photoelastic data were analyzed by over-determined least square method and crack-tip positions were moderately modified from the measured values. And these modified crack-tip positions were verified through theoretical fringe generation using calculated results.
Secondly the thickness effects were investigated for through crack in C-shaped beam and Hartranft and Sih's theory was verified. Finally stress intensity factors were investigated for various crack shape and depths for the corner crack located at inner surface of C-shaped beam.