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    Item type:Publication, Access status: without files ,
    Investigations of air atomized and coarser gas-atomized AlSi12 powders to evaluate cost reduction potentials for additive manufacturing processes
    (2021)
    Ludwig, Ina
    ;
    Kluge, Maximilian
    ;
    Jutkuhn, Dennis
    ;
    Grube, Marten
    ;
    Imgrund, Philipp
    The powder is a decisive factor for the final quality of an L-PBF part. Due to constant improvements, productivity continues to rise and more cost efficient processes can be realized. Thereby, the importance of material-related cost-savings increase and become more relevant regarding the overall manufacturing costs. In order to save costs, the processing of uncommon AlSi12 powder qualities was investigated. A broader particle size distribution (20-100 μm) and an irregular shaped powder (20-63 μm, air atomized) were compared with a standard powder (20-63 μm). All powders were characterised and the flowability was determined. In-process spreadability was monitored and determined on a test-rig. The component quality was analysed using density cubes and tensile specimens built up on an EOS M290. To increase the efficiency of the L-PBF process, coarser layer thicknesses were achieved with the coarser powder. For a final evaluation, the cost saving potentials for all powders variants were evaluated.
    Publicationtype: Conference Paper
      14
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    Item type:Publication, Access status: without files ,
    Experimental and numerical mechanical characterization of additively manufactured Ti6Al4V lattice structures considering progressive damage
    (2021-01-01)
    Drücker, Sven
    ;
    Schulze, Martina
    ;
    Ipsen, Hendrik
    ;
    Bandegani, Laura
    ;
    Hoch, Helge
    The rapid progress in additive manufacturing enables the generation of complex structures that can be customized according to the application. For instance, lattice structures show potential in medical and lightweight applications as their mechanical properties can be scaled by the volume fraction of the cells according to the local requirements given by the load paths. In order to use lattice structures in design of structural parts, the mechanical properties need to be characterized. Due to the complex nature of the selective laser melting process, manufacturing imperfections as well as the microstructure play an important role and their effects can differ depending on volume fraction, building direction and especially load case (tension and compression). The aim of this study is to analyze these effects. In addition, a deeper understanding of the failure process is necessary which is gained by 3D digital image correlation and finite element simulations incorporating progressive damage. We found that surface defects are larger for horizontal struts printed directly on the powder bed and thus show a higher influence for specimens where building and loading direction are not aligned. Moreover, porosity leads to significantly different mechanical properties contingent on the load case. Depending on the volume fraction, different failure modes are observed which are captured and explained by finite element simulations allowing to avoid stress concentrations or undesired buckling in future designs. Finally, simulations of lattice structures are compared to computationally inexpensive simulations of unit cells with periodic boundary conditions. Good agreement is found and further insights into the influence of the load introduction are gained.
    Publicationtype: Journal Article
      260