基于有限元分析的乘用车传动轴材料与结构改进

Material and Structure Improvement of Passenger Car Transmission Shaft Based on Finite Element Analysis

为获得低成本且性能良好的传动轴,以乘用车传动轴总成为研究对象进行传动轴结构设计,并根据有限元分析结果对其进行材料和结构改进。运用Catia软件建立传动轴模型,利用ANSYS Workbench软件模拟分析传动轴在最大扭转载荷下的力学性能以及传动轴的振动特性,得到传动轴在该工况下的应力、应变分布情况以及传动轴在约束情况下的振动模态。分析结果显示:传动轴的扭转刚度满足设计要求,同时传动轴在约束情况下的振动频率高于发动机最高转速的振动频率,两者不会发生共振,但传动轴总成中的十字轴的最大应力高于其屈服强度,同时凸缘叉、万向节叉和花键轴均不满足最小安全系数高于1.5的设计要求。基于这一结果对凸缘叉、万向节叉、十字轴和花键轴进行材料和结构改进,发现改进后传动轴总成中各个零件的安全系数都高于1.5,符合设计要求,同时,传动轴的扭转刚度和震动频率的最低值都有所提高,进一步提高了传动轴的安全性。

In order to obtain a low-cost and high-performance transmission shaft,the transmission shaft of passenger car was used as the research object to design the transmission shaft structure,and the material and structure were modified according to the results of the finite element analysis.The transmission shaft model was established by using Catia software.The mechanical properties,the vibration characteristics of the transmission shaft under the maximum torsional load were simulated and analyzed on ANSYS Workbench,and the vibration mode,the stress and strain distribution of the transmission shaft under this working and constraint condition were obtained.The results indicate that the torsional stiffness of the transmission shaft follows the design requirements.At the same time,the vibration frequency of the transmission shaft under constraint condition is higher than that of the maximum engine speed,so the transmission shaft would not resonate with the engine.However,the maximum stress in the cross shaft of transmission shaft is higher than its yield strength after assembling.The flange fork,the universal joint fork and the spline shaft are not meet the design requirements because the minimum safety factor should be higher than1.5.Based on these results,the material and structure of flange fork,universal joint fork,cross shaft and spline shaft are modified.It was found that the safety factor of each part in the modified transmission shaft assembly was higher than 1.5,which met the design requirements.The torsional stiffness of the shaft and the minimum value of the vibration frequency were increased,further improving the safety of the drive shaft.