A Vibration-reduced Design Method For Turbine Blade With Friction Damper

The failure of blade causes by vibration is very common. It possessed about one third of the structural abnormal events of aircraft engine. Use friction damper to reduce the response is a very simple and effective method. It is widely applied in the blades of aircraft engine, turbine system in power station and gas turbine. It can considerably reduce the vibration level of structure. So, it is very important to research the mechanism of the vibration absorption by dry friction. The result posses important theory and application value in engineering.In this paper, the research on dry friction damper is based on the mechanism of vibration damping. The two- dimensional macro-micro slip model is established. The influence factors of reducing the vibration responseare achieved by calculating example. At the same time, the method of cyclic symmetric was used, so the vibration characteristics of the whole ring of blades can be calculated. The main contributions of the paper are:(1) The two- dimensional macro-micro slip model is established. The relation between the force acting on a damper and the displacement of damper are developed. This model can be used in micro-slip and macro-slip, and it also can be used to calculate the coupled bending and twisting vibration of blades.(2) A turbine blade vibration response analysis program is developed. The influence factors of reducing the vibration responseare (such as the positive pressure, the force, the force phase difference, the contact angle and so on) achieved by calculating example.(3) Use the method of"Duplicate sector"to establish the mathematical model for the cyclic symmetry structures in the harmonic vibration response. Make a secondary development in ANSYS to get the program.Then compare the results of the sector model with the whole structure model for proving the mathematical model correct. Use the program to calculate the vibration response for the blade with the shrouds and platform. So the scale of calculation and analysis can be considerably reduced.(4) A measurement scheme was designed to measure dynamic responses of turbine blade with friction damper. The dynamic response of blades can be measured under various initial normal loads on the interface and different exciting force. The effects of the force, the initial normal load and shroud contact angle on the friction damping can be achieved.