A STUDY ON CALCULATION METHOD FOR NATURAL FREQUENCIES OF BELT SPANS IN ACCESSORY DRIVE SYSTEMS

A belt span between two adjacent pulleys in accessory drive systems is simplified as an axial moving Bernoulli-Euler beam, and a formula for estimating natural frequencies of the belt span is derived. Taking a simple accessory drive system as a studying example, which includes a driving pulley, a driven pulley, a belt and a tensioner, the natural frequencies for different belt spans are calculated using the two different models. One model is the belt-pulley coupled model, in which the belt span is modeled as a beam with bending stiffness, and another model is that the belt is modeled as an axial moving Bernoulli-Euler beam. The natural frequencies of a belt calculated with the two different models are compared for different bending stiffness of a belt, and it is shown that the difference of the calculated frequency with different models becomes large when the bending stiffness is increasing. The influences of bending stiffness and belt velocity on the calculated natural frequencies are investigated in the end.