Thermo-mechanical response and thermal matching of an integrated SiC/SiC CMC outer shroud-metal casing support structure under thermal cycling

Ceramic matrix composites (CMCs) are promising materials for advanced aero-engine hot-section components because of their low density and high temperature capability. The use of a CMC turbine outer shroud to replace a conventional outer shroud requires careful consideration of clearance matching within the assembled structure. In this study, an integrated turbine outer shroud support structure composed of a CMC outer shroud and a GH4169 metallic casing was investigated. High-temperature thermal cycling experiments were conducted in combination with transient thermo-mechanical coupled numerical simulations. The feasibility of this assembled structure under cyclic thermal loading was experimentally verified, and the deformation response characteristics of the outer shroud and casing, together with the evolution of dynamic clearance were systematically analyzed. The results indicate that the deformation response of the CMC outer shroud exhibits a pronounced lag relative to temperature increase below 300 °C. As the number of thermal cycles increased, the peak deformation of the CMC outer shroud and the metallic casing decreased by 22% and 29%, respectively. Throughout the entire cycling process, a positive clearance was maintained between the outer shroud and the casing. No structural interference occurred, demonstrating stable and superior thermal matching performance.