<p>The need for computational design optimization approaches that evaluate the mechanical behavior of the aerospace components that can be fabricated by additive manufacturing (AM) has increased significantly as the aerospace industry require more critical and challenging design requirements. The design of lattice structures, particularly topologically optimized lattice structures has become substantially effective in numerous engineering fields. Although topology optimization including lattice structures gives lightweight and high strength results, the optimized structures are challenging parts to manufacture. For these structures to switch from theory to practice, the manufacturing constraints should be considered in the design process. For this purpose, in this study, a design optimization framework is presented that utilizes the topology optimization and lattice structure optimization approaches to design an aerospace component for additive manufacturing. In this framework, the solid isotropic microstructure with penalization (SIMP)-based topology optimization is first utilized to find the relative density distribution in the design space of the component that maximizes its stiffness under the volume and strength constraints. The optimized density distribution is used to generate an initial lattice structure topology for a lightweight design. Three different lattice types have been used to have three alternative designs. A lattice structure optimization process is also carried out using an FEA based on beam element formulation in two consecutive steps. In the first step, a size optimization with a minimum diameter constraint near zero is implemented and the strut members that have diameters smaller than a threshold are removed from the topology. In the second step, another size optimization is carried out that keeps the remaining struts in the manufacturability limits of the selective laser melting (SLM) process with AlSi10Mg alloy to satisfy the volume and stress constraints while maximizing the overall stiffness. The final designs with three different lattice types have been analyzed to ensure an additional natural frequency constraint using modal analysis. These three alternative designs are comparably evaluated. Thus, a novel lattice structure design is achieved that satisfies the strength and vibration-specific requirements of the aerospace component for a real-world application. The developed lattice structure design of the aerospace component is achieved with a 30% reduction in weight while still satisfying the desired requirements compared to the existing design in use. The presented lattice design optimization framework is presented in a way that it is not application-specific so that it can also be used for the design of different components for additive manufacturing. The future work includes experimental validation of the strength and vibration performances of the SLM-fabricated design.</p>

Design of a 3D Aerospace Bracket Using Lattice Structures and Topology Optimization for Additive Manufacturing

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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