Numerical/experimental investigation of energy absorption and compressive properties in 3D-printed bi/multi-material polymeric metamaterials

<h2>Abstract</h2> In the present work, based on the literature, three types of metamaterial cells, including honeycomb, re-entrant, and cube, were selected. These cells were arranged next to each other in the samples according to the D695 standard. In addition, six different combinations of materials were considered for the bi-material and multi-material structures. Design of experiment (DOE) was performed for the data. The testing samples were fabricated using the fused deposition modeling (FDM). To check the quality of the manufacturing method, the specimen surface was evaluated by a field emission scanning electron microscope (FESEM). Then, compressive testing was done on the standard specimens. After testing, the failures in the samples and the sensitivity analysis of the results were checked. In the end, the results of the experimental test were checked with finite element simulation. FESEM images showed defects caused by filament evaporation, filament production methods, and manufacturing methods. The compressive testing data indicated that metamaterials had more favorable properties than solid structures. Honeycomb cells, re-entrant, and cubic cells had the highest yield stress. The effect of the structure type on mechanical characteristics was more than the effect of materials. Based on the sensitivity analysis, the cell had the greatest effect on weight and specific energy, and PLA material had the greatest effect on work. The numerical results of the simulation and experiments were also inappropriate in agreement with each other.