Connection stiffness modeling of rotating dovetailed blade with macro-micro interface topography

Abstract

The connection stiffness between the dovetailed blade and disk indicates the boundary condition of the blade, directly influencing the dynamic response of the blade-disk assembly and even the structural safety of the whole aero-engine. Due to the limited manufacturing precision, the contact interface of dovetailed joint is rough with macroscopic geometrical deviation inside. However, few researches are reported about the effect of macro-micro interface topography on the connection stiffness. In this paper, a stiffness model of the rotating dovetailed blade with interface topography characteristic is proposed. First, a statistical contact model is established to describe the normal and tangential contact responses of the rough interface in dovetailed joint. Then, by introducing the displacement and angle infinitesimals, the explicit expressions of the connection stiffnesses in different directions are derived out. Finally, based on the presented connection stiffness model, rotational speed, working temperature, macroscopic geometrical deviation, and microscopic topography parameters are investigated in detail. The results show a great influence of interface topography and operating parameters on the connection stiffness. The work in this paper provides a novel way to reveal the inner mechanical relationship between the macro-micro topography and the connection stiffness of dovetailed blade under the work condition, which is meaningful for the actual manufacturing and performance analysis of the aero-engine.