基于ANSYS的汽车传动轴振动特性分析与结构优化

Vibration Characteristics Analysis and Structure Optimization of Automobile Transmission Shaft Based on ANSYS

摘要: 汽车传动轴作为汽车传动系的核心组件之一，其工作的稳定性直接关系到整车性能与可靠性。为降低传动轴在外界激励下产生共振的风险，依据某乘用车车型参数，利用SolidWorks软件建立了该传动轴的三维模型，基于模态分析理论，通过ANSYS有限元分析软件对主传动轴进行自由模态与约束模态分析，获取了前12阶振型的固有频率和最大位移，分析比较了不同轴长和壁厚对传动轴模态参数的影响，深入探究了几何参数与模态参数变化规律的关系。该传动轴在第3阶和第4阶模态频率与激励频率非常接近，实际工况中很可能出现一阶共振。为此，提出了一种有效的优化策略，旨在产品研发设计阶段通过优化传动轴的几何参数改善其振动特性，预防共振引发的结构损伤。优化结果表明：(1) 随着主轴轴长的减短，传动轴的固有频率显著提升。具体而言，轴长缩短100 mm后，传动轴第3阶固有频率提升了15.29%，与激励频率保持有16.89%的安全余量；第4阶固有频率提升了15.92%，与激励频率保持有24.45%的安全余量，均超过了所要求的15%安全值，有效避开了共振区域，优化效果显著。(2) 随着主轴管壁厚的增加，传动轴频率也有所提升。在初选主轴壁厚的基础上，增加1 mm厚度后，第3阶频率从218.06 Hz提升至220.63 Hz，第4阶频率从232.14 Hz提升至237.54 Hz，分别超出激励频率186.54 Hz的8.27%和27.34%，优化结果满足避免共振的设计要求。即通过适当减小轴长和增大轴管壁厚，可有效提高传动轴固有频率。该优化策略为汽车传动轴的研发设计和现有产品结构优化提供一定的理论支持，具有显著的工程应用价值和学术研究意义。

Abstract: As one of the core components of the automobile driveline, the stability of the automobile drive shaft is directly related to the performance and reliability of the vehicle. In order to reduce the risk of resonance of the drive shaft under external excitation, SolidWorks software was used to establish a three-dimensional model of the drive shaft according to the parameters of a passenger car model. Based on modal analysis theory, free mode and constrained mode analysis were carried out on the main drive shaft by ANSYS finite element analysis software, and the natural frequency and maximum displacement of the first 12 vibration modes were obtained. The influence of different coaxial length and wall thickness on the modal parameters of the drive shaft is analyzed and compared, and the relationship between the geometric parameters and the modal parameters is deeply explored. The frequency of the third and fourth modes of the drive shaft is very close to the excitation frequency, and the first-order resonance is likely to occur in the actual working condition. Therefore, an effective optimization strategy is proposed to improve the vibration characteristics of the drive shaft by optimizing its geometric parameters and prevent the structural damage caused by resonance during product development and design. The optimization results show that: (1) The natural frequency of the drive shaft increases significantly with the reduction of the main shaft length. Specifically, after the shaft length is shortened by 100 mm, the third order natural frequency of the drive shaft is increased by 15.29%, and the safety margin with the excitation frequency is maintained by 16.89%. The fourth order natural frequency is increased by 15.92%, maintaining a safety margin of 24.45% with the excitation frequency, both exceeding the required 15% safety value, effectively avoiding the resonance region, and the optimization effect is remarkable. (2) As the wall thickness of the main shaft increases, the frequency of the drive shaft also increases. On the basis of the primary spindle wall thickness, after increasing the thickness by 1 mm, the 3rd order frequency is increased from 218.06 Hz to 220.63 Hz, and the 4th order frequency is increased from 232.14 Hz to 237.54 Hz, exceeding the excitation frequency of 186.54 Hz by 8.27% and 27.34% respectively. The optimization results meet the design requirements of avoiding resonance. That is, the natural frequency of the transmission shaft can be effectively increased by appropriately reducing the shaft length and increasing the shaft tube wall thickness. This optimization strategy provides some theoretical support for the research and development of automobile transmission shaft and the optimization of existing product structure, and has significant engineering application value and academic research significance.