Computer aided dynamic design of rotating shafts

Abstract A numerical method to calculate the critical speeds of a rotating shaft is discussed. First the eigenvalues of the system are determined. This determination involves the inversion of matrices where the elements are the result of subtraction of very large numbers so that results are inaccurate and unpredictable. This paper presents a method to circumvent this problem by introducing delta matrices. After obtaining the correct eigenvalues, a method to determine the eigenmodes is presented. The method takes in account the effect of bearing stiffness and also allows to find the translatory and conical whirl speeds.