Statistical Energy Analysis For Vibration And Noise Characteristics Of The Gearbox System

The gearbox system is widely used in various industrial equipments and its vibration and noise is a long issue. As the modern industry develop to high speed, light weight, low energy dissipation and high performance, the gearbox system needs higher power transmission, faster speed, lighter and thinner structure, which makes it face to more vibration and noise in high frequency. Because the vibration and noise not only affects the workers'working conditions, but also results in the dynamic performances of the mechanical equipments getting worse, making a reseach on the method applicable for analyzing the dynamic problem of the gearbox in high frequency has theoretical and practical values. On the basis of the viewpoint of vibratory energy transmission and the power flow theory, we study the calculation method of the vibratory power flow by the gear meshing and analyze the properties and influencing factors of vibratory energy transmitted in the gearbox system according to Statistical Energy Analysis(SEA).Firstly, we develop a dynamic model of the typical composite structure composed of plate-bearing-gear shaft-bearing-plate in the shafting system by analyzing the mechanism and transmission path of the vibration and noise of the gearbox system. Then we study the relations among the forces and deformations of the model, discuss the theoretical derivation and calculation of the stiffness of the bearing being a important part in the energy transmission path.Secondly, we take the plate-bearing-gear shaft-bearing-plate coupled system as the object, derive the dynamic transfer equation between the drving shaft and the casing plate when they occur bending vibration by the gear meshing and the mobility expression of the input power by the exciting force and power transmitted to the casing plate through rolling bearing based on the principle of mobility analysis. With the actual example, we calculate the power flow spectrum by simplifying approximately the casing plate as simply supported rectangular plateBased on the work above, considering the dense modes of the gearbox system in high frequency, we make further research on the vibratory energy transmission in the system in term of SEA. Because the modes of the finite shaft in actual engineering are thin and isolated, the coupling of the plate to the shaft can be equaled as the couping to a spring oscillator and the coupling loss factor between them is derived and calculated. Then the SEA solution and modal solution of the power flow are compared, the compared results show that the two are in better agreement. Futherly we analyze the properties and influencing factors of vibratory energy transmitted in the gearbox system by using the method above and reveal the influencing rules of the bearing stiffness and gear installation postion to the vibratory energy transmission.