Retardation of fatigue crack growth in high strength steel S690 using a modified stop-hole technique

- Double stop drill-hole (SDH) method was proposed with higher fatigue life improvement.
- The new method was studied experimentally and numerically for a SENT specimen.
- The fatigue crack initiation and crack growth lives were determined.
- Very good agreement was found between the experimental and numerical results.
- Fatigue life of double SDH was significantly higher than that of single SDH.

The purpose of this paper is to study the effects of a new stop-hole technique on the subsequent delay in fatigue crack propagation. Single edge notch tension specimens of S690 steel alloy are used to perform the fatigue crack initiation/growth tests under cyclic stress loading. A parametric study is conducted on different geometrical parameters of double stop-hole. The experimental procedure is simulated using finite element analysis and fatigue life models. The experiments including fatigue crack initiation/growth measurements and microscopic examinations beside the numerical results show that the fatigue life extension caused by the double stop-hole method is significantly more than that of the conventional single stop-hole method. The lower stress level around the double stop-hole plays an important role in increasing the fatigue initiation life from the stop-hole edge.