Effects of the indentation process on fatigue life of drilled specimens: optimization of the distance between adjacent holes

The generation of permanent compressive stresses around the holes is recognized as a valuable mean to delay the onset and propagation of the defects and to extend the fatigue life of the mechanical components. In the work, a bilateral indentation process, performed on each side of the component, is widely used in order to create a residual circumferential stress field around the area to be drilled and that persists after the drilling operation. In order to evaluate the process parameters and to identify optimal geometric solutions, several static and fatigue tests are conducted on AW 6082-T6 aluminum alloy specimen where two holes are created. In particular, experimental tests on only drilled specimens (OD) and specimens subjected to Indentation process (IP) varying the indentation depth and the center-tocenter distance of the holes are performed. Several numerical analyses, conducted in ANSYS APDL environment with explicit solver, allow to determine the influence of the distance between two adjacent holes and the effect of the indentation depth on the residual stress distribution.