Calculation method for evaluating interface slip and preload optimization design strategy for bolted connections of turbine rotors in thermal environments

• A dynamic model was established for turbine rotors with a nonlinear bolted friction interface under thermal environments. • Quasi-static thermal experiments were conducted to obtain bolted interface parameters at different temperatures. • Interface slip of bolted turbine rotors was evaluated under varying temperature and rotational speed conditions. • A preload optimization strategy was proposed for bolted connections considering coupled thermal and speed effects. As the core power unit of aircraft engines, bolted turbine rotors must operate under complex thermal and mechanical loads. The reliability of bolted connections is subject to stringent testing. To investigate the dynamic characteristics and interface behavior of bolted turbine rotors in thermal environments, this paper establishes a dynamic model of bolted turbine rotors in thermal environments based on finite element theory. A nonlinear contact mechanics friction model was used for the bolt connection interface. A process for determining the viscous-slip state of bolts at various locations in the motion state of the rotor system was given. The judgment process was applied to the finite element theoretical model. For the first time, quasi-static experiments were used to obtain the mechanical parameters of the bolt connection interface under thermal conditions. The correctness of the model was verified by the test results of bolted turbine rotors. Evaluation calculations of the interface slip of bolted turbine rotors under different temperature and speed conditions were carried out. The nonlinear dynamic response caused by the slip phenomenon at the connection interface of bolted turbine rotors was analyzed. The preload results for bolted turbine rotors to avoid interface slip under different temperatures and speeds were discussed, and a preload optimization design strategy was proposed. The dynamic analysis model of bolted turbine rotors under thermal conditions and the preload optimization design results established in this study can provide a theoretical basis for the preload design of bolted connections under thermal conditions.