Fatigue behaviour and equivalent diameter of single Ti-6Al-4V struts fabricated by Electron Bean Melting orientated to porous lattice structures

Abstract

Two types of Ti-6Al-4V single struts (1 and 0.6 mm CAD diameter) with two different build inclinations with respect to the horizontal plane: 90 degrees (vertical orientation) and 45 degrees (oblique orientation), were manufactured using electron beam melting (EBM). Quasi-static and fatigue three-point bending tests were performed for all typologies. In addition, each type of strut was scanned and reconstructed in 3D to assess their roughness, inner and outer diameters as well as to create finite element models. The range values of roughness obtained were more homogeneous in the 90 degrees fabricated struts than in the 45 degrees ones, with peak values of roughness at the 270 degrees area in the 45 degrees fabricated struts. The equivalent diameter values obtained from the quasi-static three-point bending tests were in line with the inner diameters measured from the microCT images. With regard to the finite element analysis, the use of cylindrical models with equivalent diameters in lattice structures could result in a good approximation for these studies. Mechanical properties obtained from static and fatigue tests of oblique struts (both 1 mm and 0.6 mm CAD diameter) were better than those of vertical struts. Therefore, the build orientation plays an important role in the mechanical properties of single struts.