RETRACTED ARTICLE: Research on dynamic characteristics of stator core of large turbo-generator

Abstract

The stator core of large turbo-generator experience a number of steady state alternating or transient electro-magnetic forces and unbalance forces in rotating rotor system, and may occur violent vibration which could damage the insulating layer and cause accident. Techniques for vibration reduction require knowledge of the modal frequencies , which depend on the mechanical shapes and dimensions, manufacturing and assembly of stator core as well as material properties, the electromagnetic design, ventilation and cooling design, and the calculation of modal frequencies do also, for example, magnetic permeability, electrical conductivity , thermal conductivity , Young's modulus, Poisson's ratio, mass density, etc. It is found that the generally accepted value of material properties is not valid for stator core with laminations of a large turbo-generator. This paper summarizes simply each method of determinating electro-magnetic constant and elastic properties of stator core material ,and then introduces a simple and effective method for the calculation of the modal frequencies of stator core, which Young's modulus, Poisson's ratio, and mass density are changed in the possible range ; it is then used in ANSYS workbench 12.0 program to determine the resonant frequencies curves of stator core vibration or response surfaces of natural frequencies vs. elastic constants ,and cumulative distribution function (CDF) of the resonant frequencies of stator core by statistical method (Six Sigma Analysis). ©2010 IEEE.