M1后车门模态性能设计分析学士学位论文.docx

密级：
NANCHANG UNIVERSITY
学 士 学 位 论 文
THESIS OF BACHELOR
（2010—2014年）
题 目 M1后车门模态性能设计分析

M1后车门模态性能设计分析
摘 要
模态是振动系统特性的一种表征，它构成了各种车身结构复杂振动的最基本的振动形态。为了在汽车使用中避免共振、降低噪声，需要知道结构振动的固有频率及其相应的振型。模态分析的最终目标是为了得到模态参数，为结构系统的动力特性分析、故障诊断和预报以及结构的动力特性的优化设计提供依据。
  汽车在行驶过程中的激励一般分为路面激励、车轮不平衡激励、发动机激励、传动轴激励。路面激励一般由道路条件决定，目前在高速公路和一般城市较好路面上，此激励频率多出现在1-3Hz，一般对低频振动影响较大；因车轮不平衡引起的激励频率一般低于11Hz，随着现在轮辋制造质量及检测水平的提高，此激励分量较小，易于避免；发动机引起的激励频率一般在23Hz以上，此激励分量较大；城市中一般车速控制在50～80Km/h，高速公路上一般车速控制在 80～120 Km/h，传动轴的不平衡引起的振动的频率范围在40Hz以上，此激励分量较小。由这些外界激振源会引起车门产生共振，带来噪音，极大的降低了车辆的乘坐舒适性，造成扳件的抖动开裂，零部件的疲劳损坏，车门表面保护层的破坏，削弱车门的抗腐蚀能力等。
  因此，为提高汽车产品的开发设计水平，达到优化设计的目标，需要对汽车车门进行模态分析，通过有限元计算来得到该结构在不同频率下的振型，避免因共振等原因引起的结构破坏。

关键词：车门；有限元；路面激励； 模态分析　

Abstract
Modal is one of the vibration system feature representation, it constitutes the most basic of all kinds of complex body structure vibration the vibration of the form. In order to avoid resonance in the car use, to reduce the noise, need to know the inherent frequency of structure vibration and corresponding vibration mode. Modal analysis of the ultimate goal is to get the modal parameters, for the analysis of the dynamic characteristics of structure system, fault diagnosis and forecast, and provides the reference for the optimization design of structural dynamic characteristics.
Car generally divided into the road incentives, in the process of driving wheel unbalance excitation, engine, transmission shaft incentives. Pavement incentive generally determined by the road conditions, now on the highway and generally better city road, the excitation frequency appeared in 1-3 hz, more general impact on the low frequency vibration; Caused by wheel unbalance excitation frequency is generally lower than 11 hz, as rim now to raise the level of manufacturing quality and test the incentive weight is small, easy to avoid; Engine caused by excitation frequency is in commonly mo