PSI - Issue 77

Martin Matušů et al. / Procedia Structural Integrity 77 (2026) 127 –134 Martin Matušů / Structural Integrity Procedia 00 (2025) 000 – 000

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2. Fatigue strength analysis 2.1. Description of specimens and experimental setup

This study investigates the fatigue behaviour of additively manufactured AlSi10Mg produced via Laser Powder Bed Fusion (L-PBF) printed on Concept Laser M2 with printing parameters as depicted in Table 1. Most fatigue specimens (see Fig. 1) were designed with a machined head incorporating a M18x1 thread to allow attachment to an Amsler HFP 422 resonant pulsator equipped with a 100 kN load cell (testing frequency ranging from 90 Hz up to 120 Hz based on the specimen geometry). An exception was G series, which was tested using a STEP Lab UD04 machine with a 5 kN load cell with fixed testing frequency of 35 Hz. A total of 22 series of specimens were experimentally tested resulting in 22 S-N curves. The tests cover eight distinct geometries (Fig. 1), two different load ratios — fully reversed ( R = -1) and tension-tension ( R = 0.1) — and four thermal conditions: the as-built condition without heat treatment (NoHT), and three heat-treated variants labelled T200, T240, and T300 (see Table 2 for their overview). Each series consisted of at least 10 specimens, allowing the evaluation of fatigue performance across different geometries, build orientations, and heat treatments. All specimens designated A to F have a critical cross-sectional area of 64 mm². The G geometry has a cross-section of 30 mm², and the H geometry has a cross-section area of 10 mm². However, the geometries G and H were specifically designed so that the crack propagation length remains the same across both specimen types (see Fig. 1). All specimens retained their as-built surface, with no post-processing or machining applied, except for the threaded heads required for fixture.

Table 1

Printing parameters applied on Concept Laser M2 are reported separately for the skin and for the core.

Segment Power [W] Speed [mm/s]

Skin 200 800 0.112

Core 370 1400 0.112 0.050 Core 190

Hatch spacing [mm] Spot size [µm] Layer height [mm]

140

0.025

Subsegment Scan trajectory

Surface

Subsurface

Equidistant to surface Into a depth of approx. 0.3 mm

Zig-zag

Chessboard

Domain

The rest

Into a depth of approx. 2.5 mm

A

E

C

F

B

D

H

G

Fig. 1

Specimen designation A, B up to F have the same area in the critical cross-section of 64mm 2 , the cross-section of the G series is 30mm 2 and H has 10mm 2 of the cross-sectional area in the active section.