Additive manufacturing of lightweight structures: Design and mechanical characterization

Additive manufacturing has completely transformed the production of lattice structures, permitting geometries that vary widely to optimize manufacturer conditions with respect to strength-to-weight ratios in future aerospace, automotive, and biomedical industries. The present review describes developments in design, mechanical characterization, and the challenges related to lattice structures produced by AM. Major design here involves topology optimization, unit cell classification based on strut, surface, and shell designs, and bio-inspired multi-scale architectures. Mechanical performance is affected by relative density, material systems, and AM methods (as in laser powder bed fusion), with auxetic lattices demonstrating unique properties like negative Poisson's ratios. While experimental analyses as well as computational ones have revealed that bending dominated deformation occurs in the case of sinusoidal structures and energy absorption efficiency occurs in octet-truss designs. Problems pertaining to residual stress, unmelted powder, and dimensional inaccuracies were addressed through hybrid manufacturing (like investment casting) and process optimization driven by machine learning. Future work is expected to achieve lightweight, large-scale components and perhaps functionally graded materials with defect monitoring systems. This synthesis provides a template for advancing AM lattice structures towards high-performance, application-specific solutions.