PSI - Issue 76

D. Kaschube et al. / Procedia Structural Integrity 76 (2026) 19–26

21

with σ u being the ultimate tensile strength and σ y being the yield strength of the material. The question now is how well individual models can be applied to additively produced Ti6Al4V samples using CMF and how accurately they represent mean stress influence.

2. Materials and experiments

Specimen Preparation

The sample shape for the tests was based on ISO 12106:2003, ISO 12106 (2003) and ASTM E606, ASTM E08 (2020). It is a combination of round and flat samples, which were printed flat in the pressure bed. The geometry and dimensions of the sample shape can be found in Figure 1a. The diameter of the sample in the constricted hourglass area is 5 mm in the test cross-section. All samples were printed together in a batch using an EOS P110 Velocis 3D printer with a titanium alloy Ti6Al4V grade 5 powder from Headmade Materials which particle sizes ranging from 0 to 25 µ m. The specimens were then sintered in a MUT Advanced Heating ISO 470 / 470 / 850 oven with sintering parameters according to patent EP3231536A1, Vieho¨fer et al.. All samples were slide ground after the manufacturing process. A density measurement on one sample per layer yielded relative densities between 97.4 and 98.3%. Due to varying density, samples were evenly mixed and distributed across test series to avoid a ff ecting comparability. The surface roughness of the samples was measured in accordance with ISO 16610-21, ISO 16610-21 (2013) standards, utilizing a MarTalk measuring device with a UD 120 drive unit and an LD A 14-10-2 / 60 1426 probe, covering a measuring distance of 17.49 mm. The measures resulted in an average surface roughness R a of 14 . 43 µ m , which is on the upper end of what was measured in a previous study, Kaschube et al. (2024). The grain size was determined using a Leica DCM8 microscope and the ASTM-E112 Hilliard single circle method. It averages 11.18 µ m . Young’s modulus was determined from the stabilised hysteresis of each test using the mean value, resulting in a value of 116000MPa.

(a) Specimen geometry after sintering - dimensions are in mm

(b) Photograph of the specimen showing the combination of flat and round speci men

Fig. 1: Specimen geometry

Fatigue Testing

For each of the five series, fully reversed (R = -1), strain-controlled uniaxial fatigue tests under a sinusoidal wave form were conducted in air using an electromagnetically-excited Sincotec MAC100 resonance test bench. Because of the test rig’s configuration, distinct loading frequencies were applied for the low cycle fatigue (LCF) and high cycle fatigue (HCF) domains. The experimental setup operated at frequencies ranging from 8 · 10 − 3 Hz on the lower end to 63 Hz on the upper end, which corresponded to strain rates between 1 . 8 · 10 − 4 s − 1 and 1 . 2s − 1 . Force measurements were obtained using an Interface 1020 load cell (50 kN capacity, error of ± 0 . 04%), while strain was recorded with a