Practicable multiscale topology optimization method accounting for manufacturability

Multiscale lattice structures have been an emerging solution to extreme light-weight demands in many engineering fields, while its design and optimization still rely on the traditional trial-and-error approach. Existing concurrent multiscale topology optimization methods are usually difficult to implement and not practicable due to neglecting the manufacturability of optimized structures. In this work, a direct finite element square method (DFE²) based topology optimization method proposed earlier by the authors [1] was further improved to account for manufacturability in the pre-process stage, significantly improving the practicability of proposed method. This is done by enforcing the internal connectivity, inter-connectivity and minimum manufacturable size of the DFE² based optimization results, whereby these three restrictions were incorporated into the DFE² model by defining a reasonable frozen region in meso-scale RVEs. It has been proved that the three restrictions are also satisfied in the multiscale structures reconstructed from the DFE² based optimization results via either “Copy-Paste” or “Interpolation-Filter” method. Two 2D examples including a classical lattice structure and a honeycomb structure were optimized using the proposed DFE² based topology optimization method and manufactured via FDM 3D printing. Both experimental tests and numerical simulations show that the proposed DFE² based optimization can significantly improve the structural stiffness of multiscale structures, achieving performance comparable to traditional DNS-based topology optimization. Moreover, by explicitly accounting for manufacturability, the DFE²-based approach offers substantially higher computational efficiency and good practicability, making it a promising approach for design and optimization of multiscale structures in engineering applications.