Evaluation of stress intensity factor and fatigue growth of surface cracks in tension plates

A closed form solution for the stress intensity factor (K) of semielliptical surface cracks in tension plates, obtained by Newman and Raju using 3D finite elements, is critically evaluated. This solution is compared to a recommended solution by the Society of Experimental Stress Analysis (SESA). It is also compared to photoelastic K-measurements. In addition, the aspect ratio variability of surface cracks under fatigue loading is predicted and compared with experimental data and also with the predictions of other empirical equations proposed by Portch, Kawahara et al. and Iida. Finally, the usefulness of this equation for the prediction of fatigue life of surface cracks is evaluated by a comparison with experimental results.