Experimental investigations into 3D printed hybrid auxetic structures for load-bearing and energy absorption applications

Auxetic structures possess negative Poisson’s ratio due to their unique geometrical configuration. It also offers enhanced indentation resistance, superior energy absorption capacity, excellent impact resistance, higher compressive strength, and other exceptional mechanical properties. In this study, multiple hybrid auxetic structures of three novel geometries have been designed by considering different sets of geometric parameters to numerically investigate the mechanical behaviors of the structures. The energy absorption properties and Poisson’s ratio of the developed hybrid auxetic structures have been measured under quasi-static compressive and bending loads. The numerically optimized structures from each of the three different geometries have been fabricated of acrylonitrile butadiene styrene using fused deposition modeling. Additionally, the simulated results have been experimentally validated. The validation studies have shown close agreement of their performances with the simulated results. Finally, comparative analyses of energy absorption performances have also been performed to select the most suitable structure for impact-resistant applications. Moreover, it has been observed that structure-2 exhibits superior performance in terms of maximum load-bearing capacity of 3395 N. On the other hand, structure-3 has the maximum energy absorption capacity of 51902 N.mm which is 4.85% higher than structure-1 and structure-2. Similarly, three-point bending test results have revealed that structure-2 performs better in terms of energy absorption capacity (10864 N.mm). Besides this, the effects of loading direction on deformation patterns and mechanical responses of the structures have been observed due to the changes in deformation mechanism. The high-velocity (8 m.s⁻¹) impact test results have also confirmed the suitability of structure-2 for crashworthiness applications. The comparative findings derived from this study contribute significantly in developing lightweight, energy-absorbent, and impact-resistant auxetic core-sandwiched structures for civil, defense, and automobile sectors.