Dynamic Modeling of Multistage Gearbox and Analysis Method of Resonance Danger Path

Dynamic modeling of multistage gearboxes and identification of dangerous resonance paths are necessary to avoid failure induced by resonance. Based on the lumped-parameter/finite element method, an improved dynamic gearbox model that considers the structural flexibility of the shaft and housing and can be used for dynamic analysis of variable speed processes, is proposed. Compared to previous lumped-parameter/finite element models, the proposed model does not divide the speed range into a lot of constant speeds to identify resonance; therefore, it has a higher computational efficiency (the previous model takes approximately 168 h to identify resonance whereas the proposed model takes just 47 h). Based on the proposed model, an analysis method for identifying the dangerous resonance paths of multistage gearbox is proposed. First, the natural frequencies and vibration shapes of the gearbox are calculated. Second, the time-frequency analysis of variable speed processes is used to identify resonance. Finally, the modal energy method is adopted to quantify the resonance energy of each component. Thus, the dangerous resonance paths of the multistage gearbox is determined by using the proposed analysis method. The proposed method provides a basis to reduce noise and vibrations and for fault prediction of gearboxes, and it can also be applied to other mechanical systems.