Design of Lattice Structures Based on U^* Load Path Analysis

Lattice structures are widely used in lightweight structural components and energy absorption parts. While topology optimization addresses desirable density distribution in lattice structures, there is yet no definitive solution for finding an optimum lattice layout. Since load path analysis can reveal the most efficient route for load transfer, it is preferable to align the lattice trusses with load paths for optimal structural performance. In this work, U* load path analysis is used to tailor the unit cell geometries of body-centered cubic lattice structures. The lattice layout is first determined by stiffness lines and potential lines derived from U* field in the design domain. The truss diameters are then numerically optimized to generate the lattice structure with functionally graded properties. This methodology is validated by a design problem of a cantilever structure. Results from finite element simulations and experimental tests on specimens fabricated by selective laser sintering demonstrate that the U* graded design has a significantly higher specific stiffness and strength compared with the benchmark design with a uniform cell arrangement. This approach enables engineers to create new design concepts of lattice structures with the integration of physically determined load paths.