A Bottom-Up Design Framework for Multifunctional Lattice Metamaterials.

Driven by the demands of light weighting, multifunctionality has become increasingly important in the design of lattice metamaterials. While inverse design is crucial for developing such lattice structures, traditional inverse design methods such as topology optimization often fail to fully explore the design space. To overcome these limitations, this study introduces a generative AI framework that combines 3D Gaussian voxel generation with deep learning, enabling greater structural complexity and design freedom. As a proof of concept, we employ this bottom-up design approach to shell lattice structures for optimized energy absorption and broadband sound absorption capabilities. A hybrid architecture combining a 3D convolutional neural network and a conditional deep convolutional generative adversarial network enables accurate energy absorption prediction and performance-driven structural generation. In parallel, a genetic algorithm is employed to tune heterogeneous geometries for effective broadband sound absorption. Experimental validation through 3D-printed stainless-steel lattices demonstrates the superior multifunctionality of the designed structures -achieving 40%-200% greater energy absorption than conventional shell lattices, along with a high (average coefficient ∼0.7) and broad (α > 0.5 across 1000-5800 Hz) absorption bandwidth. Overall, our proposed framework overcomes the major drawbacks of existing inverse design approaches, offering enhanced voxel-level model generation informed by physical insights.