A novel multistable honeycomb structure with tailored variable-length functions

The multistable honeycomb (MSHC) has excellent application prospects in the field of lightweight deformable structures. This study presented a novel MSHC structure with a tailored function that can achieve stable and reversible changes in structural length, consisting of four-pointed star-shaped honeycomb component and cosine curve beam component, fabricated by Fused deposition modeling (FDM) additive manufacturing technology. Experimental and numerical simulations under axial compression and three-point bending tests were conducted. The effects of MSHC structure parameters (span, height and thickness of bistable beam, and the honeycomb wall angles) on the mechanical properties were systematically analyzed. It was found that the mechanical properties were affected by the height-thickness ratio and span-height ratio of the cosine curved beam bistable structure significantly, and were slightly affected by the honeycomb wall angles. Finally, a span morphing airfoil segment for wind turbine blade, based on the novel MSHC structure, was designed, and its CFD analysis was conducted. It was observed that the lift force is positively associated with the length of the variable-length airfoil segment. The morphing airfoil can adjust its lift force within a specific range by utilizing the structural length variability, which verifies the potential of this novel MSHC in the field of load-bearing deformable structures.