Abstract
The paper presents experimental results and results of different fatigue strength assessment methods carried out on hollow specimens from AlSi10Mg with a specific design featuring an internal cavity and a cylindrical outer surface. The selected test geometry combines the design freedom of additive manufacturing with the suitability for surface temperature / thermographic measurements. Compared to classic cylindrical hollow specimens, increasing the inner diameter of the active part lessens the stress gradient in the torsion loading case, while keeping the outer dimensions still acceptably small for layer-by-layer or Laser Powder Bed Fusion technology. The surface in the tested section was left as-built, while the heat treatment recommended by the AM machine manufacturer was applied. Four loading cases were tested in the high cycle fatigue area under load-controlled configuration – push-pull, torsion, and combined loading of in-phase and out-of-phase tension-torsion. All loading cases featured fully reversed loading cycles. The results show that these specimens reach substantially higher lifetimes (or fatigue strengths) if the coacting load channels are out of phase compared to the case, in which the same stress amplitudes are applied in phase. The fatigue strength estimation performed using several multiaxial fatigue strength criteria shows that only some of the methods follow the same behavior. Session
