A novel star-shaped honeycomb with broken diagonal symmetry for enhanced tunability of equivalent elastic properties and bandgap characteristics

The design of multifunctional honeycomb structures faces critical challenges due to the inherent trade-off between load-bearing capacity and vibration isolation performance. In this paper, a novel geometrically asymmetric design approach for star-shaped honeycombs is proposed through the differential configuration of bidirectional re-entrant angles. The in-plane equivalent elastic properties of the developed diagonal symmetry-broken star-shaped honeycomb (DSB-SSH) under uniaxial loading are calculated using the theoretical model derived from Castigliano’s second theorem. Moreover, a dynamic dispersion model is developed by combining the finite element (FE) method with Timoshenko beam theory to characterize the wave propagation behaviors. The modulation mechanism of geometrically asymmetric design on the equivalent elastic properties and wave propagation behaviors of the DSB-SSH is investigated via parametric analysis and experimental measurements. The results indicate that the tunability of the equivalent elastic modulus and Poisson’s ratio is significantly enhanced due to the transition of the compressive deformation mode driven by differential configuration angles. Additional bandgaps of the DSB-SSH are opened by splitting the crossing dispersion branches induced by modal degeneracy, leading to a broadened vibration isolation bandwidth. Both the enhanced static load-bearing stiffness and the low-frequency broadband vibration isolation performance of the DSB-SSH are experimentally validated through uniaxial quasi-static compression and vibration transmission tests. Therefore, the proposed geometrically asymmetric design strategy based on differentiated re-entrant angle configurations provides a straightforward approach to tailoring the multifunctional mechanical properties of honeycomb structures without introducing additional functional components, thereby significantly broadening their practical application scenarios.