Mode shape-informed design of lightweight metal lattice structures produced by laser powder bed fusion for enhanced dynamic properties

Abstract

Metallic lattice structures are increasingly employed in advanced engineering applications where a high strength-to-weight ratio and enhanced dynamic response are required. Recent studies on functionally graded lattice structures show that these structures stand out for their tuneable properties. This study presents novel insights into the mechanical and dynamic properties of modal simulation-driven, density-gradient strut-based lattices fabricated from aluminum A205 powder using laser powder bed fusion (LPBF). Cubic bounding volume diamond unit cell lattice specimens with identical mass and four distinct gradient profiles were designed. One specimen without a density gradient and three with mode shape-informed density gradients were included in the study. A new printing parameter set was developed to enable density gradient samples to be printed at high material densities and in a robust manner. Modal and static finite element simulations were conducted to validate the dynamic property optimization of density gradient structures. Impulse excitation technique (IET) tests showed that the field-optimized design (FO) has an increase of 23.7% and 16.1% in natural frequency in two different modes, and an increase of 130% and 45% in damping capacity in the same modes, compared to the uniform density sample (NG). Compression tests showed that FO was slightly less stiff but had better maximum compressive stress values than NG. FO also outperformed the other three designs in terms of energy absorption. Despite being optimized for natural frequency and damping capacity, FO demonstrated acceptable fatigue performance with hysteresis analyses indicating greater energy dissipation per cycle than the uniform lattice design. The insights and results from this work therefore opens new opportunities for creating lightweight yet high-performance and multifunctional metal lattice structures.