Calculation and Analysis of Natural Vibration Characteristics of Serpentine Belt Drive System Based on Beam Coupling Model

Serpentine belt drive system is widely used as engine front end accessory drive system now. It's a hybrid discrete-continuous system where the motions consist of rotational vibrations of pulleys and tensioner arm, and transverse vibrations of continuum belt spans. It's easily to generate coupling vibrations, resulting in annoying noise. Therefore it's necessary to study natural vibration characteristics of the system. In this paper, an efficient method to evaluate the natural vibration characteristics of serpentine belt drive system is presented. The equation of motion of an actual n-pulley serpentine belt drive system is established in which belt spans are modeled as axial moving beams with bending stiffness. Inclusion of bending stiffness results in belt-pulley coupling not captured in moving string models. The complex modal method is used to calculate natural frequencies and vibration modes of the system. The method is verified by an example mentioned in a previous paper. Furthermore, influences of belt bending stiffness and belt axial velocity on natural vibration characteristics and degree of coupling have been investigated. The applicability of a simplified single beam model has also been discussed. The method can be popularized to solve eigenvalue problems on other hybrid systems composed by continuums and discrete bodies.