Using spectrograms to identify resonance and design corrective measures for a fan assembly

Abstrakt

The operation of rotating machinery is associated with vibrations that can indicate the onset of faults. This paper deals with the vibro-diagnostic analysis of a radial belt fan, where initial measurements of the overall vibration level indicated a critical condition of the electric motor. By applying advanced analysis of spectrograms recorded during run-up and coast-down, it was found that the dominant source of vibrations is not a component fault, but resonance caused by insufficient stiffness of the fan structure. This diagnosis was further confirmed by an analysis of the fault frequencies of the bearings, which ruled out damage to the motor bearings. In the conclusion of the paper, specific structural modifications are proposed to reinforce the frame and a strategy for their verification using the Finite Element Method (FEM) is recommended. The paper demonstrates the importance of advanced diagnostic methods for the correct identification of the root cause of the problem and the effective design of corrective measures.