Abstract

Architected metamaterials utilize unique geometries to enhance the mechanical and physical properties of structures. This study investigates the energy absorption capabilities of additively manufactured hybrid strut-based metamaterials, produced using Fused Deposition Modeling (FDM) with Polylactic Acid (PLA). Compression tests were conducted on six novel hybrid strut lattice designs to analyze their structure-property relationships. The designs integrated Kelvin cells, edge struts, octagonal shapes, hex trusses, face-centered components, and corner diagonal struts. The combination of “Kelvin Cell + Octagon” achieved excellent energy absorption efficiency, with the highest Specific Energy Absorption (SEA) of 1450 kJ/kg. Through the synergistic effect of octagonal geometry and Kelvin cell structure, controlled deformation and delayed buckling are realized to release the energy fully and maximize stress wave interaction. However, the configuration of the “Edge Struts + Hex Truss” configuration was not far away either, exhibiting an SEA of 1388.89 kJ/kg, owing to the effective load distribution provided by the hexagonal truss structure. Other configurations had much lower SEA values: 275 kJ/kg for “Kelvin Cell + Hex Truss” 185.71 kJ/kg for “Kelvin Cell + Edge Struts” 162.5 kJ/kg for “Edge Struts + Corner Diagonal” and 26.67 kJ/kg for “Edge Struts + Face Centre”. Using microscopy to look at failed samples showed that shapes with hexagonal and octagonal parts increased SEA by making stress distribution more even and limiting deformation during compression. The unit cell geometry is the critical factor for deciding upon the energy absorption capacity of metamaterials. This work provides useful insights to design optimized additively manufactured metamaterials to achieve high energy absorption, which will be useful to applications such as automotive crash protection, aerospace components, personal protective equipment, and vibration damping systems. The “Kelvin Cell + Octagon” and “Edge Struts + Hex Truss” configurations emerge as highly effective designs, balancing strength, ductility, and energy absorption efficiency for advanced engineering applications.