Optimal design and experimental validation of 3D C/SiC-TC4 hybrid lattice structures with lightweight, thermal insulation, and excellent mechanical properties

• Tensile, compressive and bending properties of 3D-C/SiC and TC4 at different temperatures (25 °C, 200 °C and 500 °C) are tested. • The temperature and strain-related constitutive models of 3D-C/SiC composites and TC4 alloy have constructed. • The geometrical parameters of 3D-C/SiC-TC4 panel/core composite structures have been optimized. With the development of aerospace spacecrafts (hypersonic vehicle), the strong airflow and ultra-high temperature environment encountered during service are more complex. It is necessary to further develop spacecraft skin structures with excellent bearing capacity, light weight and high temperature resistance. In this paper, the novel 3D C/SiC-TC4 hybrid lattice structures have been developed taking TC4–3D C/SiC-TC4 as panel structures and 3D C/SiC-TC4 as cylindrical core structures. First, the tensile, compressive and bending properties of 3D C/SiC composites and TC4 alloy at different temperatures (25 °C, 200 °C and 500 °C) are tested. Then, the temperature and strain-related constitutive models of 3D C/SiC composites and TC4 alloy have constructed. By using simulation and NSGA-II genetic algorithm, the geometrical parameters of 3D C/SiC-TC4 panel/core structures have been optimized by limiting the surface density and taking strength and thermal insulation as indexes. The results show that the compressive, tensile and shear elastic modulus of 3D C/SiC at room temperature are 3.94∼11.1 GPa, 31.93∼62.26 GPa and 721.96∼978.31 MPa, the strengths are 213.64∼242.07 MPa, 130.05∼154.53 MPa and 17.53∼39.53 MPa; with increasing temperature, the compressive and tensile elastic modulus are decreased. The optimized thickness of panel composite structure is 9.54 mm, the diameter and fiber angle of core composite structure are 9.56 mm and 0.25° Finally, the excellent mechanical properties of the hybrid lattice structure under different temperature conditions have been verified combining experiments and numerical simulations. The research has reference value for the material selection and structural design of spacecraft skin structures in the future.