Design for Additive Manufacturing: Enhancing the Strength-to-Weight of Mechanical Metamaterials for Energy Applications

Additive manufacturing (AM) coupled with mechanical metamaterials (MMs) enables architected structures whose performance is governed by both geometry and material, offering practical routes to high strength-to-weight and controlled energy absorption. This work investigates AM design strategies, hybridization, and functional grading of lattice structures with the aim of lightweight structures for energy and infrastructure applications. All the designed structures have constant relative density, allowing for the separation of geometric effects from the addition of mass. Different designs of the hybrid and graded models were simulated using quasi-static compression tests (loaddisplacement, stiffness, and energy absorption) that employed nonlinear finite element analysis (FEA) to capture geometric nonlinearity, contact, and post-buckling effects. Across multiple models, graded lattices achieved a 56% increase in stiffness, a 69% increase in compressive strength, and a 46% increase in energy absorption compared to a benchmark cubic lattice, while preserving stable collapse modes that are favorable for energy absorption. The failure response, as measured by the FEA, included both the deformation pattern and stress distributions, providing design insights that can be linked to stiffness and strength in hybrid and graded strut connectivity. Beyond the realm of materials research, the results have direct impact on energy efficiency and sustainability. Stronger and lighter components can help improve the efficiency of electric vehicles, increase the durability of wind turbine blades, and lower the energy demand of aerospace and defense systems. Overall, the results suggest that AM-compatible hybridization and functional grading offer a practical approach to developing higherperforming lightweight mechanical metamaterials for energyefficient and sustainable future structures.