A novel hybrid auxetic honeycomb with enhanced load-bearing and energy absorption properties

Auxetic structures with negative Poisson's ratio exhibit excellent performance in cushioning, shear resistance and energy absorption, but their load-bearing capacity is usually poor. To address this drawback of the conventional Auxetic structure, a star-rhombic honeycomb (SRH) design is proposed in this paper to improve its load-bearing capacity. Analytical models of the elastic modulus and Poisson's ratio of this structure for different loading rections are developed. Quasi-static compression experiments were conducted on SRH specimens fabricated selective laser melting (SLM) technique. Good agreement was achieved between the simulated and experimental stress response curves and deformation patterns. It was found that the SRH structure possessed better elastic modulus and energy absorption capacity than the SH structure without sacrificing the auxetic properties. The elastic modulus and Poisson's ratio of SRH under the x loading direction are more sensitive to the changes structural parameters. An optimum energy absorption performance is achieved for an appropriate ratio of the inner rhombic strut thickness to outer reentrant strut thickness (k = 0.5). The specific energy absorption of SRH is improved by 136% and 75% compared to that of the conventional reentrant honeycomb (RH) and star hon-eycomb (SH), respectively. It has advantages for application scenarios with requirements for both auxetic and load bearing properties.

Automated summary

This paper proposes a star-rhombic honeycomb (SRH) design to improve the load-bearing capacity of conventional auxetic structures while maintaining their auxetic properties. Analytical models for the elastic modulus and Poisson's ratio of this structure under different loading directions are developed. Quasi-static compression experiments conducted on SRH specimens fabricated using selective laser melting (SLM) technique validate the improved elastic modulus and energy absorption capacity of the SRH structure. An optimum energy absorption performance is achieved for an appropriate ratio of the inner rhombic strut thickness to outer reentrant strut thickness (k = 0.5). The SRH structure exhibits significantly higher specific energy absorption compared to conventional reentrant honeycomb (RH) and star honeycomb (SH) structures, making it advantageous for applications requiring both auxetic and load-bearing properties.