Effect of Vibration Mode on Material Damping

Kunihiko Ishihara

Logarithmic decrement, Damping ratio, Material damping, Vibration mode

In turbo-machineries such as a turbine and a compressor, the vibrations of blades which are central parts, have been become problem. The causes are the resonance of blade due to an inlet distortion, a wake of preceding blade row and a potential interference of succeeding blade row, and a self-excited vibration like a flutter. In general, it is said that the material damping can only be expected in the high centrifugal force field. Fortunately, this time we have a chance to carry out the rotating test of the long blade and we obtained the logarithmic decrement of the first to the sixth modes. According to the results, it was clarified that the mode order gave effects to the logarithmic decrement little. Then in this study, it will be presented that the experimental fact is reasonable by using the concept of specific damping.

https://dx.doi.org/10.31873/IJEAS.9.05.10