Vol.6, No3, 2006, pp. 97-110
UDC 669.15:539.375

Abstract

This study presents the application of linear elastic fracture mechanics to the prediction of fatigue crack growth of surface cracks in BS 4360-50D steel and in weld metal of its butt-welded joint under 4-point bending. The prediction is based on the available experimental data and the fatigue crack growth law proposed by Branco et al. To calculate stress intensity factor ranges, the solutions reviewed by Scott and Thorpe have been used. Computer programmes have been developed for this prediction. The predicted crack growth curves and relationships between the crack length in the through thickness and along the surface directions correlate well with the experimental data.

The effects of initial crack configurations on the crack shape, crack profile and variation of stress intensity factors at the deepest and surface points have a unique characteristic similar to other published results. The prediction of crack profiles has shown that the final failure of the specimen is caused when the crack along the surface reached the sides of the specimen. The shapes of the profiles depend on the thickness, width and initial crack configuration.

Keywords: surface crack, fatigue crack growth, stress intensity factor, fatigue testing