Bending Performance and Crashworthiness Characteristics of Sandwich Beams with New Auxetic Core

Structures with enhanced mechanical properties and crashworthiness are competing materials in the transport industry to reduce structural weight, and auxetic materials are the ideal choice. Auxetic metamaterials are the class of cellular structures designed to possess negative Poisson's ratio. The current study evaluates newly developed re-entrant diamond auxetic metamaterial's in-plane and out-of-plane three-point bending performance. A series of experimental and numerical studies are performed to assess the quasistatic performance and crashworthiness characteristics of 3D-printed re-entrant diamond auxetic core and sandwich panels. The results are compared with regular re-entrant panels of the same unit cell size. The deformation and failure mechanism of both auxetic structures, core and sandwich, are discussed. Real-time displacement contours on the specimen surface are visualized using advanced image processing and finite-element methods. The new re-entrant diamond auxetic members outperformed energy absorption characteristics in in-plane and out-plane directions. Compared to the counterpart, the new metamaterial has improved 88.33% and 29.24% in-plane energy absorption as a core and sandwich, respectively. 13.51% and 13.35% increments in energy absorption as a core and sandwich are observed for re-entrant diamond structures compared to the regular re-entrant system in the out-of-plane direction.

Automated summary

This study evaluates the in-plane and out-of-plane bending performance of newly developed re-entrant diamond auxetic metamaterials. Experimental and numerical studies compare the performance of these materials with regular re-entrant panels of the same unit cell size. The results show significant improvements in energy absorption for the new metamaterial.