【作者】 田红涛；

【导师】 杨明忠；

【作者基本信息】 武汉理工大学 ， 机械制造及其自动化， 2008， 硕士

【摘要】 随着经济的迅速发展,汽车已经进入普通老百姓的家庭,极大地方便了人们的日常生活和工作。人们对汽车舒适性方面的要求也迅速向国际水平靠拢,购买汽车的时候,人们不仅仅关注汽车的价格、安全性,同时对汽车振动噪声等与舒适性相关的要求也越来越高。随着汽车技术的不断进步,车内振动与噪声明显降低,而一些子系统和零部件的振动噪声问题(例如制动器的振动噪声问题),变得越来越突出,因此对制动器进行振动噪声方面的研究显得非常重要。这对制动器的结构设计具有重要的实用价值。本文首先介绍了有限元的思想和有限元分析的几种常用的软件,然后以国产某型汽车为例,假设制动力矩均匀分布,经过简化计算求出制动盘、制动片、制动支架的制动力矩。然后建立制动器各构件的CAD模型,考虑到划分网格的需要,建模的时候忽略了构件中一些不重要的凹台和圆角,采用mapped法将建立的模型网格化,确定合适的边界条件和自由度,将制动力矩加载到制动器的有限元模型上,进行结构分析和模态分析。分析结果表明:制动盘的固有频率在368～699Hz之间,制动盘的动刚度不足;制动片的尖角部位有应力集中;制动支架的动刚度不足。同时各部件的不同阶频率有重合的情况,容易引起结构共振。希望采用改变厚度,尖角部位倒圆角,同时在制动盘上开设通风道的等办法来降低振动噪声产生的概率。将优化设计后的模型导入ANSYS中,重新进行模态分析,结果显示各个构件的应力集中的情况有了较大的改善,固有频率都有所升高,但是外界的激励频率一般比较小,同时不同阶频率重合的现象也有所改善,在理论上减少了振动噪声发生的概率,这种降低盘式制动器振动噪音的方法有待进一步通过试验鉴定。本文的工作主要在于用模态分析的方法分析制动器振动噪声的发生源,这种方法不仅适用于分析制动器,而且为机械设备中相互耦合的部件之间的振动噪声的检测,提供了一种可以借鉴的降低振动噪声方法。更多还原

【Abstract】 With the rapid development of Chinese enconomy, vehicles have used by ordinary people’s families and given more convenience to people’s life and work. Now customer’s expectations for new vehicles are not only high safety and low price, but aslo high comfortableness, such as low vibration noise. With the development of automobile technology, the noise and vibration of the whole vehicle are decreased very much, but the vibration noise of the parts and subsystems such as brakes becomes more and more prominent. So the rearch on vibration noise in brakes are more important than before, its results will be valuable for the structure design of brake.In this thesis, the principle of finite element and several common softwares of finite element analysis are introduced firstly, and then some type of the car made by Chinese company have been taken for example. Though simplified calculation, it is supposed that the distribution of the braking moment is uniform, then the braking moments of its disc, block and anchorage are determined. For establishing the CAD model of the components of the brake, the grid division of the model are taken into account, and those unimportant concaves and fillets are also overlooked.By means of the mapped method, the appropriate boundary conditions and degrees of freedom for the established model grid are determined. Meaningwhile, the braking moment will be loaded on the finite element model for the mode and structure analysis.The results showed that when the natural frequency of brake disc is between 368～699Hz; the dynamic stiffness of brake disc is not enough, there is stress concentration at the sharp angles of the brake block; the dynamic stiffness of the brake anchorage is deficient. When there is the coincidence phenomenon of the frequencies of the different steps for brake parts, the resonant phenomenon will occur. For reducing vibration noise of the brake, the frequency will be reduced by means of some methods such as changing the thickness, making fillets at the sharp angles and opening the ventilations at the brake disc.The design model optimized is put in ANSYS, the modal analysis is made again, its results shows that situation of stress concentration is improve tremendous and the natural frequencies of various components have been increased. Because the external excitative frequency is generally very low, the coincidence phenomenon of different frequency bands has been also improved. These methods decrease the vibration noise effectively. This improvement method will be tested further.The significance of this thesis is to present the method of analyzing the reasons of brake vibration noise by means of the modal analysis principle. This method applies not only to the noise detection for the brake, but also to the noise detection for the mutual coupling components in machinery industry, and it will provide a new method for the noise detection in engineering.更多还原