Abstract:The drive axle is one of the core components of the micro-vehicle transmission system, which bears complex loads and affects the safety, comfort and power of the vehicle. The performance of drive axle has a significant effect on vehicle NVH (noise vibration and harshness). In order to obtain the influence laws of drive axle vibration response and further implementthe active control of the dynamic characteristics, a multi-factor coupling vibration model is established based on lumped mass method considering the key excitations of the hypoid gear transmission system in drive axle, including time-varying mesh stiffness, damping, transmission error and impact. The differential equations of the nonlinear vibration model were derived on the basis of Newton’s Law, which are further solved by the Runge-Kutta method. After performing the optimization of the hypoid gears, the influence laws of input speed and load torque changes on the vibration characteristics are discussed considering the numerical solutions on the verticality, torsion and axial directions for both the driving and driven gears. Computational results indicate that the proposed solution can reduce the gear vibration, and a nearly chaotic phenomenon is caused by the complicated vibration laws of the vertical and axial dimensions for the driving gear and driven gear, while a quasi-periodic state is for the torsional dimension. In addition, the changes in input speed and loading torque have the largest impacts on the axial vibration, followed by the vertical dimension, and the smallest in the torsional dimension. The results of the vibration test and data analysis for the gear transmission system also demonstrate that higher dynamic performance can be obtained for optimized samples, which also supports the theoretical analysis of the drive axle. The proposed approach is expected to be applied to improve dynamic performance of certain products by analyzing the key excitation factors and predicting the vibration response of the drive axle.