A nonlinear thermo-mechanical coupling model for simulating functionally graded nose cones under aerodynamic environment

Abstract

A nonlinear thermo-mechanical coupling model (NTMCM) based on the finite element method (FEM) is presented to simulate the nonlinear thermo-mechanical coupling behavior of functionally graded nose cone structures under hypersonic flight conditions. The model accounts for the temperature dependence and spatial variation of material properties, with the effective properties of functionally graded materials (FGMs) determined using the rule of mixtures. The Newton–Raphson iterative technique is employed to solve the discretized nonlinear thermo-mechanical coupling equations. The accuracy of the proposed model is validated through comparison with numerical results reported in the literature. Combining CFD++, aerodynamic forces and heating from the external flow field are obtained as boundary conditions for the thermo-mechanical coupling analysis of the structure, and the nearest-neighbor interpolation method is employed to transfer the aerodynamic-structural interface information. Numerical simulations are performed to investigate the effects of flight speed and material gradient index on the nonlinear thermo-mechanical coupling responses of the nose cone structure. The results show that the temperature and stress are primarily concentrated in the windward head region of the structure, both of which increase with flight speed. Additionally, a higher material gradient index significantly reduces the internal temperature gradient of the nose cone, enhancing its thermal protection performance. This study provides a novel computational tool to guide the application of FGMs in thermal protection systems for hypersonic vehicles.