箱式动力结构的振动传递特性分析

针对箱式动力结构大型化、柔性化的特点,结合有限元法,以二级减速箱为对象研究不同激励条件下齿轮轴-轴承-箱体的振动传递特性.箱体采用Craig-Bampton动力缩减法缩聚到轴承孔中心处作为柔性子结构,啮合传递误差和输入轴扭矩波动分别作为激励源,考虑齿轮的时变啮合刚度、啮合错位、齿侧间隙、轴向重合度等非线性因素,计及轴段、齿轮的重力效应,基于轴段节点的思想分析了箱体缩聚节点处及轴承内圈处的动态加速度响应.最后基于Block Lanzos法提取箱体的固有特征频率.数值分析结果表明,输出轴轴承在动响应传递过程中没有起到衰减作用,应该替换以防影响整个系统的性能;减速箱的箱体设计保守,可以根据箱体缩聚节点处的动态响应为激励条件进行优化. 

Analysis on vibration transmission characteristics of box-like power structure

Box-like dynamic structures are proceeding at the direction of maximization and flexibility. Vibration transmission characteristics of geared shaft-bearing-housing were studied by finite element method under different excitation conditions for two-stage reducer. Gearbox was used as a flexible substructure reduced to the center of bearing hole by Craig-Bampton dynamic reduction technique. When mesh transmission error and torque fluctuations of input shaft served as excitation source respectively, meanwhile nonlinear factors such as time-varying meshing stiffness, meshing misalignment, gear tooth backlash, axial contact ratio, and the gravity effect of shafts and gears were taken into consideration, dynamic acceleration response at gearbox reduction nodes and bearing inner ring were analyzed based on the thought of shaft section node. Finally, the natural frequencies of gearbox were extracted based on Block Lanzos method. Numerical analysis results show that the bearings of output shaft do not play an attenuation effect in the process of dynamic response transmission, and should be replaced to prevent the influence on the performance of whole system. Gearbox is conservatively designed that needs to be optimized according to the dynamic response of gearbox reduction nodes.