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. It's a hybrid discrete-continuous system including rotational vibrations of pulleys and tensioner arm, and transverse vibrations of continuum belt spans. It's easily to generate coupling vibrations and the 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 equations of motion of an actual n-pulley serpentine belt drive system are 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 state space method is used to calculate natural frequencies and 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 speed on natural vibration characteristics and degree of coupling are investigated. The method can be popularized to solve eigenvalue problems on other hybrid systems composed by continuums and discrete bodies.