抄録
In resonance of a finite group of blades, stress increasing and decreasing effects often occur. As the first step in the elucidation of the cause of these effects, this paper thoroughly investigates phenomena related to these effects, from a broad perspective. The natural frequencies, normal modes and resonant stress ratio of the first-order tangential flexural vibration of a finite group of blades are calculated by means of Rayleigh-Ritz method, for a very wide range of the thickness ratio between the shroud and blade. The results indicate that, (1) the elastic curves of the blades are identical or similar in each normal mode, (2) the resonant stress increasing and decreasing effects are not related to the form of the blade's elastic curve in the normal mode, but are only related to the ratio of the blades' amplitudes in it, i. e., the waveform of vibration, and offer a sound base for the theoretical investigation of the cause of these effects, which is reported in another paper.
