Sub-Interval Combination Method for Dynamical Characteristics of Shrouded Turbine Blades

In order to analysis the uncertain problems of dynamical characteristics of shrouded turbine blades accurately, an interval method for complex structures combined by interval theory and finite element method has been presented. The solution procedure for the interval dynamical characteristics is given based on the commercial finite element software. Taking the dispersion of operation temperature, contact status of the shrouds and angular stiffness of firtree root into account, the modal characteristics and vibration response of a shrouded turbine blade are studied, and as a consequence the effects of typical uncertain parameters of structures and loads on the vibration characteristics of blade are obtained. The results show that the computational efficiency can be improved more than 10 times, and the relative error of the calculated results is less than 50% compared with Monte Carlo method, in particular the results obtained by the interval method are more reliable. Moreover it is not necessary to get the information about the probability distribution characteristics for the uncertain parameters by this developed method, which indicates a better engineering application prospect compared to most probabilistic methods.