Probability Calculation for Natural frequency of Anisotropic Stator Core of Large Turbo-Generator

摘要

Techniques for vibration reduction and design of stator core require knowledge of its modal frequencies, which depend on the geometry shapes, dimensions and material properties. The material properties of stator core are mainly related to its laminated process and assembly as well as the operating temperature of turbo-generator. It is found that the generally accepted value of material properties is not valid for the stator core with laminated silicon steel slice and operating at about 110-120 Celsius. This paper simply summarizes the method of determining elastic constants of stator core material, and then introduces a simple and effective method for the calculation of the modal frequencies of stator core. The material model of stator core is thought anisotropic. The elastic modulus, Poisson's ratio, and mass density are all considered as uncertainty variables, obeying Gaussain distribution, and changing in the possible range; and then ANSYS workbench 14.5 program is used to determine the resonant frequencies and corresponding probability of stator core, and response surfaces of natural frequencies vs. elastic constants by statistical method (Six Sigma Analysis). The results have an important guiding role for the laminated structure design, manufacture process, the fixedness and the vibration isolation design of stator core.