MW520镁合金变速器箱体有限元分析及结构优化

发布时间：2018-04-27 07:35

本文选题：AZ91D镁合金 + 变速器箱体　；参考：《济南大学》2015年硕士论文

【摘要】：汽车正常行驶主要依靠传动系统稳定的动力输出,在这一过程中发动机与变速器相互配合完成复杂的速度变换与动力传递,其中变速器的作用是将发动机的输出动力通过飞轮、离合器等转换为变速器的输入转速然后按不同的传动比要求输出不同的转速以满足不同车速、不同牵引力的工作要求,能够使发动机发挥其最佳性能。其中变速器箱体要具有足够的强度刚度来抵抗外载荷的作用,这是影响变速器总成可靠工作和齿轮传动系统动力稳定输出的关键因素,箱体刚度不足,会引起轴承安装位置的偏移,造成轴承的非正常磨损破坏,大大降低轴承寿命,同时引起齿轮传动的错位,偏载,降低齿轮寿命,增大变速器噪音;箱体强度不足,则箱体承载能力不够,从而会引起变速器箱体撕裂破坏,影响汽车正常安全行驶。镁合金在各金属合金中属于较轻的金属结构材料,比强度大比刚度高,减震性、散热能力好,承受冲击载荷能力强,其中AZ91D镁合金不仅是一种绿色环保的金属材料,而且其具有密度低承载能力好等特点,将其应用到工业产品中可以大大降低产品质量提升产品性能;汽车工业中,汽车自身的重量是影响燃油消耗的重要因素之一,随着我国环境问题日渐严峻,国家节能减排政策的不断推出,使低碳经济概念不断深入人心,并且我国在轻卡行业实施的由国Ⅲ级排放标准升为国Ⅳ级以上排放标准要求,使得汽车零部件产品轻量化生产成为车企积极探索研究的重要方向。镁合金AZ91D具有质量轻、比强度大等优点,已经在航空领域得到了广泛的应用并且验证了镁合金优越的机械性能,同样,将镁合金应用于汽车领域,不仅可降低整车质量,提升车辆机动性能,而且降低油耗,节能环保,整车NVH性能也会得到显著改善。因此,本文以AZ91D镁合金作为变速器箱体材料,利用有限元方法对箱体结构进行模拟仿真,在保证变速器正常工作的前提下对箱体进行结构轻量化分析设计,提升变速器的使用性能,实现低碳、绿色环保制造。课题以MW520镁合金轻卡变速器为研究对象,应用UG三维软件建立了变速器的总成模型,利用HYPERMESH前处理软件考虑各零部件之间的接触非线性关系处理三维模型,通过控制单元的长宽比,翘曲度,雅阁比率从而建立了高质量的有限元模型,根据齿轮和传动轴系的参数利用MASTA建立了MW520镁合金变速器传动系统有限元模型,根据汽车总成技术条件及台架试验标准设定了镁合金变速器箱体一档、倒档工况下的转速、运转时间,并在一档、倒档工况下施加2.5倍载荷,提取了箱体在载荷作用下轴承孔处的载荷谱,利用HYPERMESH将载荷谱作为载荷边界条件简化施加在箱体有限元模型相应位置,利用ABAQUS软件研究了在此两种工况下箱体承受载荷的应力分布同时研究了变速器箱体在冲击载荷下的应力分布情况,优化了箱体结构局部高应力区域,对优化后的箱体模型进行有限元数值分析,分析结果表明镁合金AZ91D材料的变速器箱体满足汽车正常工作要求。
[Abstract]:The normal driving of a car is mainly dependent on the dynamic output of the transmission system. In this process, the engine and the transmission cooperate with each other to complete the complex speed transformation and power transfer, in which the function of the transmission is to convert the engine's output power through the flywheel, the clutch and so on to the input speed of the variable speed device and then according to the different transmission ratio. It is required to output different speeds to meet different speed, and the work requirements of different traction forces can make the engine play its best performance. In which the gearbox should have enough strength stiffness to resist the external load, which is the key factor affecting the reliable work of the transmission assembly and the power stability of the gear transmission system. Lack of stiffness will cause the offset of bearing installation position, cause abnormal wear and tear of bearing, greatly reduce bearing life, and cause the dislocation of the gear transmission, partial load, reduce gear life and increase the noise of transmission; the box body strength is not enough, which will cause the gearbox to tear and destroy, and affect the car positive. The magnesium alloy is a lightweight metal structure material in all metal alloys, which has high specific stiffness, shock absorption, good heat dissipation and strong impact load capacity. AZ91D magnesium alloy is not only a kind of green metal material, but also has the characteristics of low density and low bearing capacity. It is applied to industrial products. In the automobile industry, the vehicle's own weight is one of the important factors affecting the fuel consumption. With the increasingly severe environmental problems in China, the continuous introduction of the national energy saving and emission reduction policy makes the concept of low carbon economy deeper and deeper, and China's implementation in the light card industry is from country III level. The emission standards have been promoted to the requirements of national level IV emission standards. The lightweight production of auto parts products has become an important direction for the active exploration and research of the car enterprises. Magnesium alloy AZ91D has the advantages of light mass and strong specific strength. It has been widely used in the field of aviation and verified the superior mechanical properties of magnesium alloy, and the same, magnesium alloy will be combined. Gold should be used in the automotive field, not only to reduce the quality of the vehicle, to improve the motor performance, to reduce fuel consumption, to save energy and environmental protection, and to improve the performance of the whole vehicle NVH. Therefore, this paper uses AZ91D magnesium alloy as a gearbox material, and uses the finite element method to simulate the structure of the box, so as to ensure the normal work of the transmission. The lightweight analysis and design of the structure of the box is carried out to improve the performance of the transmission and achieve low carbon and green environmental protection. The research object is MW520 magnesium alloy light card transmission. The model of the transmission is established by using UG 3D software, and the contact nonlinear relationship between the components is considered by the HYPERMESH pretreatment software. A high quality finite element model is established by controlling the length to width ratio, warpage and the accord ratio of the control unit. The finite element model of the transmission system of the MW520 magnesium alloy transmission is established according to the parameters of the gear and transmission shaft system using MASTA, and the speed change of magnesium alloy is set according to the technical conditions of the automobile assembly and the standard of the bench test. With one gear box, rotating speed and running time under the working condition of reverse gear, 2.5 times load is applied to the one gear and reverse gear, and the load spectrum of the bearing hole is extracted under the load of the box. The load spectrum is simplified to the corresponding position of the finite element model of the box by HYPERMESH, and the two kinds are studied by using the software of ABAQUS. The stress distribution of the box under the load under the working condition is also studied. The stress distribution of the gearbox under the impact load is studied. The local high stress area of the box structure is optimized. The finite element numerical analysis is carried out on the optimized box model. The analysis results show that the gearbox of the magnesium alloy AZ91D material meets the normal working requirements of the automobile.

【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U463.212;TB115

【参考文献】