5. Conclusions

In order to identify the surface integrity parameters that control the fatigue strength of a 2024-T351 aluminium drilled part, fatigue tests were carried out on open-hole specimens and the surface integrity of the holes was characterized with a study scale and techniques suitable for aluminium drilled surfaces. An innovative technique for the residual stress evaluation of aluminium drilled parts, the HOCT, was implemented. The main conclusions of the study are as follows:
The study focused on the fatigue life of open-hole specimens as a first step, in order to avoid the phenomena associated with the introduction of a fastener (impact of the tightening torque, impact of the assembly clearance or interference level, etc.). In future works, it would be interesting to study the fatigue life of assemblies of drilled parts with fasteners, to assess the influence of the hole surface integrity in this case.
Finally, in order to be able to improve the fatigue life of aircraft structures, the influence of the drilling process (tool geometry, cutting parameters, associated thermomechanical loading) will have to be studied in more detail in order to develop a drilling process generating optimum hole surface integrity.