PSI - Issue 34

Federico Uriati et al. / Procedia Structural Integrity 34 (2021) 184–190 Author name / Structural Integrity Procedia 00 (2021) 000–000

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Figure 3, Integrated design workflow for additive manufacturing production of structural components. Numerical process simulation was also included in the adopted workflow of Fig. 3 to forecast distribution and magnitude of residual stresses and part deformation upon fabrication and after release from the build plate. The commercial software Amphyon (Additive Works GmbH, Germany) was used for this objective. The software predicts residual stress and deformation caused by the layer-by-layer fabrication adopting the inherent strains approach,(Keller e Ploshikhin 2014), and the thermal history to which the job is subjected. If some zones are identified as critical in terms of manufacturability or post-process intervention is necessary to go back to the design phase and iteratively modify the model as indicate in Fig. 3. 3. Component fabrication The composite job of Fig. 4 was built from the AlSi10Mg alloy powder in a SLM500 system (SLM Solution GmbH - Germany) using printing parameters defined by the expert technology partner (Beam-It, Fornovo Taro, Italy). The layer thickness was 50 µ m, build plate temperature of 150°C and an energy density of 32.62 J/mm 3 . Supports were made by thin lattice structures. As far as the material, AlSi10Mg is widely used in combination of selective laser melting technology for its good processability and high mechanical properties useful for the automotive sector. Reference static properties were R m =390 MPa; σ y = 210 MPa and A%=5%. The build job produced in relation with this work was composed of i) ten optimized suspension arms printed according to two different orientations to investigate the differences introduces by dissimilar surface direction and supports position (please note Fig.4a shows only five items); ii) sixty four miniaturized specimens divided into four different orientations produced to evaluate effect of build direction on fatigue performance of the material(Nicoletto 2020) (Fig.4b) and to generate fatigue data useful for the part qualification phase; and iii) two calibration beams for evaluation of inherent strains for the process calibration (Keller e Ploshikhin 2014) (Fig.4c).

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Figure 4 Composite build job with a) suspension arms oriented in two directions; b) miniature fatigue specimens with four different orientations (Nicoletto 2017) ; c) process calibration beams After fabrication, the build job underwent a direct aging heat treatment where the platform was kept at a temperature of 200°C for 4h. Then, all optimized parts were removed from the baseplate and supports eliminated manually followed by sandblasting to improve the surface quality. Miniature specimens were removed and left in the as built