Calculation of Natural Frequencies of Motor-Fan System Depending on Mathematical Modeling Technique

Abstract

Eigenvalues and Eigenvectors for rotating machines equivalent its natural frequencies and mode shape. Several techniques can be implemented to calculate Eigenvalues and Eigenvectors. In this paper a theoretical technique depending on mathematical modeling for motor-fan system used for natural frequencies and mode shape determination of that system. A motor-fan system that contains motor, coupling, gearbox and fan is required to find its mode shapes and natural frequencies. A comparison between theoretical (calculated) and measuring values of natural frequencies has done. A mathematical model for that system is implemented with its differential equations. A code created by MATLAB is used for solving these equations to get the Eigenvalues and Eigenvectors. The results of the technique were very accurate and nearest measuring natural frequencies and mode shapes values.