离心压缩机用斜齿轮副的有限元分析及疲劳寿命预测

发布时间：2019-01-17 21:30

【摘要】：国内外的统计数据显示，工程中疲劳破坏占机械设备所发生破坏的比例达60%~90%，可见疲劳为机械结构最常见的失效形式。在空气压缩机中，增速斜齿轮副连接发动机和叶轮，是空气压缩机中的一个关键部件，其使用寿命决定了整机的无故障工作时间。传统的设计往往基于静强度设计方法，采用加大许用安全系数或降低许用应力的方法来提高其可靠性，往往不能保证其运行的可靠性和安全性。斜齿轮副主要承受循环载荷，一旦发生疲劳失效、断齿故障，不但影响设备的正常运转，而且带来不小的经济损失。因此，根据齿轮副的工作条件做出准确的受力分析，得出其所受应力应变情况、掌握破坏规律、估算其疲劳寿命是十分必要的，，同时也可以为空气压缩机的检查、维修、保养等提供必要的数据。为此，本文以空气压缩中的增速斜齿轮副为对象综合运用弹性接触有限元理论、齿廓修形理论、多体动力学理论、疲劳损伤理论及模态分析理论，分别对齿轮副进行静强度分析、齿廓修形、动力学仿真、疲劳寿命预测及模态分析，对空气压缩机的抗疲劳设计具有较大的参考价值。本文研究工作包括如下几个方面： ①在ANSYS中建立齿轮副的多齿啮合有限元模型并加载求解，求得啮合过程中的应力分布，并对齿顶出现啮合冲击的情况采取齿廓修形以改善轮齿受力，最后研究了摩擦系数、修形量对齿顶应力峰值的影响情况。研究结果表明：修形后齿轮的最大应力为236.223MPa，采用齿廓修形有效地降低了齿顶出现的啮合冲击现象。最大应力有随摩擦系数和修形量的增加而降低的趋势。 ②在动力学分析软件ADAMS里面建立斜齿轮副的虚拟样机模型，两齿轮之间添加碰撞，求得动态啮合力，并将其与理论计算值比较，结果表明：啮合力的理论计算值与仿真计算值误差约5%，可以为疲劳分析提供载荷谱。 ③根据材料的性能，拟合材料的近似S-N曲线，并结合应力结果、载荷谱基于疲劳损伤理论预测斜齿轮副的疲劳寿命，结果表明：齿轮副的安全系数均大于1，忽略极少数对齿轮的整体寿命影响较小的低寿命点，可达到64.17年，大于设计要求的20年使用寿命，且有很大富裕。最后研究了表面粗糙度、载荷对齿轮疲劳寿命的影响情况。 ④对斜齿轮副进行模态分析，求得其前6阶固有频率和相应振型。结果表明：齿轮副啮合频率为6078.25Hz远大于前6阶固有频率，且基频大于主从动轮的转频，所以系统在运行过程中不会发生共振，具有良好的动态特性。
[Abstract]:The statistics at home and abroad show that the proportion of fatigue damage to mechanical equipment in engineering is 6090. It can be seen that fatigue is the most common failure form of mechanical structure. In the air compressor, the speed increase helical gear pair connects the engine and the impeller, which is a key component in the air compressor. Its service life determines the fault-free working time of the whole machine. The traditional design is often based on static strength design method, the method of increasing allowable safety factor or reducing allowable stress is adopted to improve its reliability, which can not guarantee its reliability and safety. The helical gear pair is mainly subjected to cyclic load. Once fatigue failure and broken tooth failure occur, not only the normal operation of the equipment is affected, but also the economic loss is not small. Therefore, according to the working conditions of the gear pair, it is very necessary to make an accurate force analysis, to obtain the stress and strain situation, to master the failure law, to estimate its fatigue life, and to inspect and maintain the air compressor at the same time. Provide necessary data such as maintenance. Therefore, in this paper, the elastic contact finite element theory, tooth profile modification theory, multi-body dynamics theory, fatigue damage theory and modal analysis theory are applied to the helical gear pair in air compression. The static strength analysis, tooth profile modification, dynamic simulation, fatigue life prediction and modal analysis of gear pairs are of great reference value to the anti-fatigue design of air compressor. The research work in this paper includes the following aspects: 1 the finite element model of multi-tooth meshing of gear pair is established in ANSYS, and the stress distribution in meshing process is obtained by loading and solving. In order to improve the force of gear teeth, the influence of friction coefficient and shape modification on the peak stress of tooth top is studied. The results show that the maximum stress of the modified gear is 236.223 MPa, and the tooth profile modification can effectively reduce the meshing impact phenomenon at the top of the gear. The maximum stress tends to decrease with the increase of friction coefficient and shape modification. (2) the virtual prototype model of helical gear pair is established in the dynamic analysis software ADAMS. The dynamic meshing force is obtained by adding collision between the two gears, and the dynamic meshing force is compared with the theoretical calculation value. The results show that the error between the calculated and simulated values of the meshing force is about 5, which can provide the load spectrum for fatigue analysis. (3) according to the properties of the material, fitting the approximate S-N curve of the material and combining with the stress result, the fatigue life of the helical gear pair is predicted by the load spectrum based on the fatigue damage theory. The results show that the safety factor of the gear pair is more than 1. A few low life points which have little influence on the overall life of gears are neglected, which can reach 64.17 years, which is larger than the 20 years' service life required by the design, and has a lot of affluence. Finally, the influence of surface roughness and load on the fatigue life of gear is studied. (4) the modal analysis of helical gear pair is carried out, and the first 6 natural frequencies and corresponding modes are obtained. The results show that the meshing frequency of gear pair is much larger than the first 6 natural frequency and the fundamental frequency is larger than the rotation frequency of the master-slave wheel, so the system will not resonate during the running process and has good dynamic characteristics.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TH452;TH132.4

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