【作者】 赵富强；

【导师】 王铁；

【作者基本信息】 太原理工大学 ， 机械工程， 2012， 博士

【摘要】 变速器作为车辆传动系统的关键部件,起着改变汽车驱动力和车速的作用。随着汽车产业的快速增长,变速器呈现了系列化、模块化、轻量化的发展趋势,这对变速器快速设计和生产提出了更高要求。在保证变速器可靠性前提下,为了进一步加快新品的研发,有必要对变速器疲劳寿命试验方法进行改进以缩短研发周期。变速器作为复杂系统,从系统角度出发结合零部件疲劳状况进行分析成为一个新的研究方向,此外,在实际生产中,传统的时频分析方法应用效果欠佳,不能较好满足实际生产中对疲劳测试信号的动态分析和监控的需要。因此,本文基于疲劳寿命预测理论、机器学习理论和振动信号分析方法,在大量变速器疲劳寿命试验基础上对变速器疲劳寿命试验方法进行改进、对变速器疲劳状态进行特征辨识、并对变速器各档寿命进行了预测,对掌握试验变速器疲劳寿命状态特性具有理论和实践意义。论文主要研究内容如下：1)对变速器总成进行了有限元仿真和模态试验分析,得到了变速器低阶固有频率及振型,通过对比理论和试验数据验证了模态参数识别的可信性并确定了变速器薄弱环节,为疲劳试验提供了依据。基于疲劳损伤累积理论,分析了变速器载荷谱、应力循环次数的关系以及关键零件在不同载荷强化系数作用下的损伤度,提出了“删低强高”的变速器加速疲劳试验方法；与等幅疲劳方法对比得到了等幅疲劳、加速疲劳这两种试验方法关于循环次数、损伤度的当量关系；通过对比试验验证了这种加速疲劳试验方法保持了失效机理的正确性。2)完成了三轴式、双中间轴式、行星轮式三种变速器疲劳寿命试验和振动信号测试,建立了基于峭度、均方幅值指标与采样点次数(循环次数)关系的变速器疲劳寿命曲线；结合变速器试验工况以及疲劳失效状况,分析了各变速器关键档位疲劳寿命曲线的变化趋势,并得出双中间轴式变速器的抗振动冲击性优于三轴式和行星轮系变速器的结论。3)基于循环平稳理论、独立分量分析法和支持向量机分类法,提出了针对同类传动结构、不同载荷的变速器疲劳状态进行特征辨识的综合分析方法；分别以峭度、峭度绝对值、峭度平方作为特征量,采用一对一、一对多、直接构造多分类器的支持向量机分类方法,对三类变速器疲劳寿命试验数据进行特征提取和辨识,验证了这种方法的合理性。4)建立了齿轮—轴—轴承的变速器动态仿真模型,分析了循环周期内动态接触应力和弯曲应力变化；基于疲劳损伤理论和非线性临界平面有限元分析法,快速预测各齿轮的疲劳累积损伤区域；考虑了变速器齿轮疲劳寿命主要影响因素对材料S-N疲劳寿命曲线进行修正,提高了预测的准确性；通过对比疲劳寿命仿真与试验结果验证了这种方法。5)提出了基于模糊支持向量机回归的变速器疲劳寿命预测方法,建立了变速器应力循环累积因素和温度变化因素影响的核函数,实现了对试验变速器的各档齿轮进行寿命的预测；通过对三类变速器的各档疲劳寿命的试验值与预测值比较验证了这种方法。更多还原

【Abstract】 Transmission, as one of vehicle transmission system key components, plays a crucial role on the automobile driving force and speed. As the fast growth of automobile industry, this thesis describes the present status of transmission, and that is serialization, combination and lightweight. Then, it is necessary to put forward the requirements of transmission rapid design and production. In the conditions of assuring transmission reliability, to accelerate the development of new products further, exploring new ways of transmission fatigue life test is of great necessity. Transmission, as a complex system, from system perspective, analyzing combined with parts fatigue condition, has become a new direction. What is more, in practical production, the present effect of traditional time-frequency analysis method is far from perfect. Therefore, it has not been able to satisfy the need of signal dynamic analysis and monitoring in fatigue test. So, on the basis of the fatigue life prediction theory, the statistics analysis theory and vibration signal fault theory, transmission fatigue condition and life prediction are analyzed in this thesis. It is of significance in theory and practice to master transmission fatigue life dynamic characteristics.The main research contents of this thesis are roughly as follows.1) Through condutng finite element simulation analysis and modal test analysis, the low order natural frequencies and corresponding modes of transmission assembly are extracted. The test data is coincided with analytical results, which indicates the reliability of modal parameters. Modal analysis shows the weak position of transmission, which provides a basis for fatigue test. In view of the fatigue damage cumulative theory, by analyzing the relationship between transmission load spectrum and stress cycle times, and the damage degree of key parts with different load strengthen coefficient, a accelerating fatigue test method is put forward. With constant amplitude fatigue contrast test methods, under two test methods, constant amplitude fatigue test method and accelerated fatigue test method, the equivalent relationship of cycle time and damage degree is determined. It can be easily verified that accelerated fatigue test methods keep the correctness of the failure mechanism through contrast test.2) For three series transmissions, concluding triaxial transmission, double countershaft transmission and planetary gear train transmission, fatigue life dynamic test and vibration signal test are conducted. And transmissions fatigue life curve, which is based on kurtosis, mean square amplitude index and sample point number, is established. Combined with transmission fatigue invalidation condition, through analyzing key gear fatigue life curve changes of each transmission, it can be concluded that anti-vibration and impact performance of double countershaft transmission is superior to that of triaxial transmission and planetary gear train transmission.3) On account of cyclostationarity theory, independent component analysis and support vector machine classification, this thesis puts forward comprehensive analysis method for pattern recognition, which is aiming mainly at studying transmission fatigue state, and this kind transmission consist similar transmission structure,but different load. Kurtosis, kurtosis absolute value and kurtosis square are regarded respectively as independent component. By using the classification methods of support vector machine, which include one-to-one, one-to-many and direct constructing multi-class classification support vector classifier, this thesis deals with fatigue life test data of three kinds transmission, and conducts feature extraction and recognition for these data. The testl results show that the test method is correct.4) A dynamic simulation model of gear-shaft-bearing transmission system is established. Then, the dynamic contact stress and the bending stress variation of gear system are analyzed throughout the cycle. Based on the fatigue damage theory and nonlinear critical plane finite element analysis method, transmission fatigue life of every gear is obtained.Taking into consideration the main factors that influence transmission gear fatigue life, material S-N curve is modified in this thesis, and the accuracy of forecast are improved, and fatigue damage cumulative failure area of each gear is forecasted quickly.5) On the basis of fuzzy support vector machine regression theory, kernel function, which is influenced by transmission stress cycle accumulation factor and temperature variation factor, is proposed with transmission fatigue life prediction method. Residual life forecast is realized for every gear of transmission, and the feasibility of the technique is proved through comparing predicted valuel with test value of three kinds of transmission fatigue life.更多还原