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Additively manufactured sandwich structures with periodic cores are widely used in \linebreak lightweight construction due to their high stiffness-to-weight ratio and geometric flexibility. However, in the laser powder bed fusion (LPBF) process, the enclosed nature of unit cells such as FCC (face-centered cubic) and BCC (body-centered cubic) poses challenges for powder removal, potentially compromising manufacturability and part quality. To address this, spherical cut-outs were introduced at cell corners to enable powder evacuation. Finite element simulations were carried out to assess the impact of these changes on the effective material properties, including stiffness and Poisson's ratio, under different loading conditions.
In contrast, TPMS (triply periodic minimal surface) unit cells, which are inherently self-supporting and open-porous by design, offer a promising alternative for LPBF applications. Preliminary simulations demonstrate their potential to maintain mechanical integrity while overcoming powder removal challenges. A MATLAB-based framework was developed to generate and analyze TPMS unit cells, with features for seamless meshing, direct export to Abaqus, and a novel gradation approach enabling tailored density distributions across sandwich cores.
The results highlight the trade-offs created by spherical cut-outs in FCC and BCC unit cells, where manufacturability is improved at the expense of stiffness. TPMS-based structures, on the other hand, maintain their mechanical performance while simplifying the manufacturing process. This study provides important insights into the design and evaluation of periodic core structures for LPBF, which has significant implications for lightweight applications in the aerospace and automotive industries.
