The Vibration Characteristics of Steam Turbine Blades with New Friction Damping Structures
The hysteresis curves that show the relationship between the tangential friction force and relative displacement of the contact surface were measured. The equivalent stiffness and damping of the friction contact surface under different normal loads were computed by harmonic balance method (HBM). The finite element model of steam turbine blades with new friction damping structures was established. The effects of friction between the contact surfaces were considered by using spring damping elements to connect the friction damper and the blade. The equivalent stiffness and damping which were calculated by the experiment results were applied to the spring damping elements under different rotational speeds. Based on the natural frequencies which were computed by finite element analysis, the Campbell diagram of the whole blades was obtained. The results showed that there were no 3-coincide points in the working speed range.