Abstract: Dimension errors in root part of a turbine blade, which are formed in manufactural process or by wearing out during service leads to contact conditions between the blade root and disc groove changed. As a result, a shift of fundamental frequencies of the blade and redistribution of stress in the root will occur, which possibly causes failure of the blade. Influence of the dimension errors on contact status between the blade root and the disc groove and on fundamental frequencies of the blade is investigated by three dimensional finite element analy-ses. A finite element model of a blade with fir shape root and its matched disc groove is constructed and then analyzed by taking account of large deformation of the blade and contact nonlinear in the root. The results show that locations of the errors have significant influence on fundamental frequencies especially for bending modes of the blade. Magnitude of the error has almost no influence on frequencies but affects contact status and thus affects the stress field in the root. The results also suggest that considering the contact between blade root and disc groove is necessary to obtain more real fundamental frequencies of a blade-disc component.

Key words: Blade, Dimension error, Finite element analysis, Fundamental frequency Contact analysis