Surface roughness effects on the fatigue behaviour of gyroid cellular structures obtained by additive manufacturing

Surface roughness effects on the fatigue behaviour of gyroid cellular Ti-6Al-4 V structures obtained by additive manufacturing were investigated. The normalized fatigue strength values for 10<^>6 cycles, obtained from the S-N curves, were in the range of 0.21-0.23. Finite element analyses showed that stress peak points were located on the stress concentrators due to surface defects, and scanning electron microscopy images showed that crack initiation was located at the surface. It is concluded that the expected good fatigue behaviour due to the curvature in the junctions of the struts, is diminished because of the superficial roughness contributing to the notch effect.