EXPERIMENTAL K-CALIBRATION FOR CORNER CRACKS UNDER BENDING LOADING

The geometric correction function F in the expression for stress inten sity factors has been determined experimentally by a compliance method for bar-shaped specimens of Al-7475-T761 (with a rectangular cross-se ction) cyclically loaded in bending at R = -1 and room temperature. Th e experimental method makes it possible to resolve the behaviour of th e crack during the tensile and compressive portions of the loading cyc le. This leads to the introduction of the initial notch size as an add itional correction parameter. The development of the equilibrium shape of the crack during crack growth up to long surface distances has bee n investigated. These results have been used for the determination of F. A comparison with literature data is presented.