A Multi-Sized Unit Cell Design Method to Design Lattice Support Structures for Complex Geometries in LPBF

Abstract Composed of individual unit cells strategically arranged to achieve a desired function, lattices are a promising solution for laser powder bed fusion (LPBF) support structure design. Despite their many advantages (e.g., multifunctionality and reduced material cost), prior work in lattice support structure (LSS) design primarily focused on parts with horizontal support domains (e.g., cantilever beams) that are not translatable to complex domains, thereby limiting their application. This work introduces a multi-sized unit cell design optimization (MSO) method to create LSS for parts with complex surfaces. The proposed method utilizes voxelization to identify and sort the locations of box-like unit cells of different sizes. It also allows for efficient design optimization through a modified simulated annealing-based optimization algorithm. The effectiveness and efficiency of the MSO method are demonstrated through the case study of an adapter pipe for a high-temperature heat exchanger. For this demonstration, LSS using multi-sized unit cells are designed to increase heat transfer rate while considering structural integrity and material cost constraints. When the optimally-directed results derived from the MSO method are compared to benchmark designs of equal-sized unit cells, it achieves an average heat transfer rate that is 16% higher while satisfying volume, stress, and deformation constraints.