Abstract: Aiming at the problems of vibration and noise exceeding the standard of a new batch of fans, the AVANT7008 data acquisition analyzer was used to analyze the vibration time and frequency domain characteristics of the whole machine, outer frame and net cover of the fan under different speed conditions, the key techniques of free suspension modal test of the fan assembly were summarized. A multisensor triaxial vibration noise acquisition and analysis test method was proposed. The Modal Genius modal simulation analysis software was used to study the modal characteristics of the fan frame free suspension model, model data driving point was determined according to the actual sensor placement position, the modal characteristics of the free suspension model of the fan frame was studied, natural frequency and main mode of the frame was obtained. The results show that the frequency range that affects the vibration of the fan is between 280 Hz and 300 Hz and the frequency around 23.13 Hz (when the fan speed is 1 400 r/min),the lateral vibration is larger than the longitudinal vibration amplitude, and the vibration structure of the outer frame structure with improved fragile position is significantly reduced in the X, Y and Z directions, which verifies the effectiveness of the designed modal test scheme.
Key words: vibration characteristics; modal test; hammer excitation; natural frequency; acceleration sensor