Effect of strurt shape mechanical and absorption performance of periodic lattices.

This study investigates the mechanical behavior and energy absorption characteristics of Modified Periodic Lattice Structures (MPLS), a class of mechanical metamaterials fabricated through Fused Deposition Modeling (FDM) using PLA+. Five lattice samples with varying strut-hole diameters (MPLS-0, MPLS-5, MPLS-10, MPLS-15, and MPLS-20) were designed and subjected to uniaxial compression tests in accordance with ISO 13,314 standards. The impact of strut perforation on key mechanical metrics-including strength, energy absorption density (EAD), specific energy absorption (SEA), and efficiency of energy absorption (EAE)-was evaluated through both experimental testing and finite element (FE) simulations using Abaqus. The results revealed a clear trade-off between perforation size and mechanical integrity: MPLS-0 (solid struts) achieved the highest yield strength (13.61 MPa), EAD (13.26 J/cm³), and SEA (2.41 J/g), whereas MPLS-20 (largest perforations) dropped to 6.90 MPa, 6.04 J/cm³, and 1.15 J/g, respectively. Intermediate designs provided balanced outcomes: MPLS-5 and MPLS-10 preserved 83-75% of the solid strut strength while offering up to ~ 10% weight savings. FE simulations confirmed these findings and highlighted localized stress concentrations and torsional effects in hollow-strut lattices, especially in MPLS-15 and MPLS-20. Interestingly, higher-porosity lattices exhibited prolonged deformation before densification, suggesting potential advantages for energy dissipation and composite reinforcement despite reduced strength. Overall, moderate perforation (MPLS-5 and MPLS-10) offered an effective compromise between mass reduction and mechanical performance, emphasizing the role of controlled geometry in designing lightweight, impact-resistant components for aerospace, automotive, and protective systems.