Thermo-mechanical analysis of a multilayer hollow cylindrical thermal protection structure with functionally graded ultrahigh-temperature ceramic to be heat resistant layer

In this study, a multilayer thermal protection system (TPS) of hollow cylindrical structure for hypersonic flight vehicles (HFVs) is modeled and its thermo-mechanical responses are investigated. The multilayer structure has an ultrahigh-temperature ceramic (UHTC) or a functionally graded ultrahigh-temperature ceramic (FG-UHTC) outer layer for heat resistance, a SiC aerogel middle layer for thermal insulation, and a TC4 inner layer for load bearing. Temperature dependent material properties as well as time dependent boundary conditions are considered. Governing equations of the temperature and displacement fields are carried out and thermo-mechanical responses of the structure, especially of the heat resistance outer layer, are calculated by the differential quadrature method (DQM) and Newmark method. Influences of component volume fraction, porosity, gradient distribution and the thickness of FG-UHTC layer on the thermo-mechanical responses are discussed by numerical examples. The main aim of this paper is to introduce the design and mechanical analysis methods of FG materials into heat resistant composites for TPSs, as well as to propose an effective numerical process to solve the complete nonlinear governing equations.