Vibration isolation of variable fan speed in HVAC systems

Edward Przydróżny,

Juliusz Walaszczyk


This article analyses two samples of existing vibration isolation systems. The first sample applies to rubber absorbers, the second, to spring absorbers. The article presents a method of setting the parameters of a second order differential equation describing oscillation movement. The equation parameters were selected on the basis of amplitude measurement and rotation velocity in two representative points – (i) in the resonance and (ii) at the maximum rotation velocity when the influence of the damping factor for the oscillation amplitude can be ignored. Equations of motion simulations were performed and the results were compared with the actual values of displacement and the velocity vibration platform.


Ibrahim R.A., Recent advances in nonlinear passive vibration isolators, Journal of Sound and Vibration 314, 2008, 371-452.

Yang C., Yuan X., Wu J., Yang B., The research of passive vibration isolation system with broad frequency field, Journal of Vibration and Control 19(9), 2012, 1348-1356.

Le T.D., Ahn K.K., Experimental investigation of a vibration isolation system using negative stiffness structure, International Journal of Mechanical Sciences 70, 2013, 99-112.

Liu X., Huang X., Hua H., On the characteristics of a quasi-zero stiffness isolator usingEuler buckled beam as negative stiffness corrector, Journal of Sound and Vibration 332, 2013, 3359-3376.

Hanieh A.A., Preumont A., Multi-axis vibration isolation using different active techniques of frequency reduction, Journal of Vibration and Control 17(5), 2010, 759-768.

Alujević N., Wolf H., Gardenio P., Tomac I., Stability and performance limits for active vibration isolation using blended velocity feedback, Journal of Sound and Vibration 330, 2011, 4981-4997.

Michalczyk J., Transient resonance of machines and devices in general motion, Journal of Theoretical and Applied Mechanics, 50, 2, Warsaw 2012, 577-587.

DiGiovanni M., Thomas R., Spearman P.E., Fan Vibration Specifications, ASHRAE Journal, February 2008.

Goliński J.A., Wibroizolacja maszyn i urządzeń, WNT, Warszawa 1979.

ISO 10816-1 Annex B, Mechanical vibration – Evaluation of machine vibration by measurements on non-rotating parts, 2003.