Mechanical robustness of 3D-printed metal honeycomb structures

Researchers at the University of Limerick in Ireland have investigated the mechanical properties of 3D-printed metal honeycomb structures under different load rates. Honeycomb lattice structures are increasingly being used in aerospace and biomedical engineering thanks to their impressive strength.

In the first study of its kind, the metal lattices were made from 316L stainless steel using laser powder bed fusion (LPBF) and material extrusion (ME). Dr. Solomon Obadimu and Associate Professor Kyriakos Kourousis then tested how different loading rates affect the failure behavior of the structures – with a focus on the ME process.

Using digital image correlation (DIC), they analyzed how the grids failed at different lateral load speeds. Statistical models and equations were used to predict this behavior.

“Our results not only contribute to the further development of additive manufacturing, but also have significant implications for applications in industry,” say the scientists. The study showed that both LPBF- and ME-manufactured honeycomb structures are influenced by the loading rate. As the rate increased, energy absorption, yield and compressive stresses increased, but not the modulus of elasticity and compaction strain.

In the ME samples, smaller honeycomb cells with a higher density exhibited greater strength. In addition, the heat generated during the testing process led to thermal softening. Digitally monitored deformation patterns showed three shapes: Vertical “I”, “X” and diagonal shear strains.

Although geometrically identical, the results varied for the same structures. The compressive behavior strongly depended on the AM process used, with ME showing stronger variations.

Overall, the study provides important insights for potential applications of robust 3D-printed metal grids in industry. Details can be found in the scientific paper “Load-rate effects on the in-plane compressive behavior of additively manufactured steel 316L honeycomb structures“.