Modular stayed 3D-lattice structures manufactured by MEX-AM: buckling behaviour and energy absorption

Slender lattice structures offer significant advantages in mechanical applications due to their high stiffness and energy absorption capabilities; however, they are inherently prone to buckling. Although stay-based reinforcement concept have proven effective in two-dimensional lattice, extending them to three-dimensional (3D) structures presents challenges in both design and manufacturing. This study aims to develop a material-extrusion manufactured stayed 3D-lattice based on a modular design that enables non-planar stay arrangements. The goal is to improve the ultimate load capacity and energy-absorption performance of the lattice through the introduction of stays. Material-extrusion additive manufacturing was used to fabricate modular stayed lattice specimens, followed by uniaxial compression testing and digital image correlation to evaluate mechanical performance and deformation behaviour. Three types of connectors and three types of stayed unit cells were fabricated through a modular strategy and printing parameter optimisation, and assembled into six distinct lattice configurations. Buckling behaviour, relative density, relative strength, and energy absorption were studied. The results demonstrate that the stay concept can be effectively applied to 3D-lattices, increasing the ultimate load by up to a factor of 3.53 and enhancing energy-absorption capability to approximately 81%. The buckling behaviour could be tuned across five lattice configurations by varying unit cell types and additional reinforcement strategies. The connectors remained intact without observable micro-cracking, which is favourable for recyclability. Overall, the proposed modular stayed 3D-lattice framework offers a recyclable and effective strategy to enhance stability and energy absorption, providing fundamental data for selecting optimal configurations for intended applications.