A novel bimaterial shuriken-shaped negative thermal expansion structure for suppressing supersonic aero-thermoelastic flutter

To enhance aeroelastic flutter performance of hypersonic vehicles under severe aerodynamic heating, this paper proposes a novel negative thermal expansion (NTE) metamaterial termed the bimaterial shuriken-shaped auxetic structure (BSAS). First, the equivalent thermal expansion coefficient and shear modulus of the BSAS are derived as functions of three microstructural parameters, L, r, and θ, and the theoretical prediction is validated by finite element analysis (FEA) with errors below 1%. Subsequently, a macroscopic nonlinear aerothermoelastic analysis framework for BSAS-core laminates in supersonic flow is established by integrating the thermomechanical model with von Kármán large-deflection theory and first-order piston theory. The results indicate that the critical flutter pressure of BSAS-core laminates reaches 111.9% of that of existing high-performance NTE-core laminates, while the BSAS core exhibits a relative density of only 19% of the NTE cores. These results demonstrate the effectiveness of the BSAS as a functional core for suppressing supersonic aerothermoelastic flutter, and provide a lightweight, thermally adaptive design strategy for advanced hypersonic vehicle structures.