Programmable mechanical responses of a hybrid star-rhombus honeycomb based on digital design method

Hybrid honeycombs with programmable mechanical responses have received widespread attention due to their multifunctionality and superior mechanical properties. To improve the tunability of the hybrid honeycomb, a hybrid star-rhombus honeycomb (HSRH) is designed using a digital design method. Different coding strategies are obtained by programming the distribution position of the rhombic structure inside the star-shaped honeycomb. HSRH with different coding strategies are designed by coding "0 '' (unreinforced structure) and "1 '' (reinforced structure). The compressive stress, Poisson's ratio and energy absorption of HSRH are investigated by experiments and numerical simulations. The results show that HSRH produces ordered deformation in compression with multi-plateau characteristics. HSRH has superior energy absorption in the X direction than in the Y direction. The specific energy absorption can be regulated between 2.41 - 5.02 J/g and 1.57-4.29 J/g in the X and Y directions, respectively. HSRH with unidirectional and bidirectional filling strategies exhibit a double-plateau feature in the X and Y directions, while the HSRH with hierarchical filling strategies has a three-plateau feature in the X direction. The filling ratio plays a decisive role in the energy absorption of honeycomb and has a positive correlation with the energy absorption properties. Furthermore, diverse deformation modes can be customized by introducing pattern-coding strategies. The codable deformation mode and programmable energy absorption of the HSRH are achieved by controlling the filling ratio and coding strategy (i.e., coding the number and location of embedded rhombic structures). This study provides a digital method for the design of programmable hybrid honeycombs and facilitates their application in multi-tasking energy absorbers.