发动机曲柄连杆机构的扭振及疲劳分析

发布时间：2018-06-28 02:04

本文选题：柴油机 + 曲轴　；参考：《太原理工大学》2016年硕士论文

【摘要】：随着汽车行业的迅速发展,人们对汽车的各项性能指标都提出了更高的要求。汽车的噪声,振动和平顺性(NVH)是衡量汽车舒适性的重要指标,发动机作为整车振动的重要来源,已经受到研究者和厂商的广泛重视。曲轴是发动机重要的零部件,其性能的优劣对发动机的整机性能产生非常大的影响。柴油机曲轴的扭振特性,以及疲劳可靠性的研究对于发动机的NVH有重要意义。本文以云内4100柴油机作为研究对象,应用有限元软件ANSYS、多体动力学软件ADAMS及Design Life疲劳寿命分析软件,对曲柄连杆机构进行了静强度测试、动力学仿真以及疲劳寿命分析,主要进行了以下工作:1)应用三维软件进行建模及装配,得到曲轴、连杆、活塞等零件的基本参数,并进行相应的力学分析。2)对曲柄连杆机构进行多刚体动力学仿真,得到其典型工况下的各个零件的运动学关系。3)替换曲轴为柔性体,并进行刚柔耦合仿真,对曲轴系进行扭振的谐响应分析,研究不同的转速及负载对曲轴扭转振动幅值的影响。结果表明,曲轴的扭转振动随发动机转速以及负载的提高,均存在变大的趋势,且转速对曲轴扭振的影响更为显著。同时得到曲轴在稳态过程中的各个主轴颈、连杆轴颈的压力载荷谱,为进一步的曲轴疲劳寿命研究,提供重要的载荷边界条件。4)在ANSYS中生成有限元的模型,通过自由模态分析结果得到曲轴的固有频率以及振型,并在此基础上根据多体动力学仿真得到的极限载荷,对其进行静强度校核,结果表明,曲轴的静强度超过其使用标准,满足要求。为后续的疲劳寿命分析提供依据。5)最后,结合多体动力学软件得到的载荷谱与有限元分析所得的曲轴在各个工况下的应力应变分析结果,以及通过材料的各项属性拟合出S-N曲线,对曲轴做了疲劳寿命预测,分析疲劳寿命云图的结果显示,曲轴的最危险部位的寿命次数达到了1310,认为曲轴不会发生疲劳破坏,达到了曲轴的寿命要求。
[Abstract]:With the rapid development of automobile industry, people put forward higher requirements for the performance of automobile. Vehicle noise, vibration and ride comfort (NVH) is an important index to measure vehicle comfort. As an important source of vehicle vibration, engine has been widely paid attention to by researchers and manufacturers. Crankshaft is an important part of engine. The torsional vibration characteristics and fatigue reliability of the crankshaft of diesel engine are of great significance to the engine NVH. In this paper, using finite element software ANSYS, multi-body dynamics software Adams and Design Life fatigue life analysis software, the static strength test, dynamic simulation and fatigue life analysis of crank linkage mechanism are carried out. The main work is as follows: (1) using 3D software to model and assemble, the basic parameters of crankshaft, connecting rod, piston and other parts are obtained, and the corresponding mechanical analysis .2) the multi-rigid-body dynamics simulation of crank and connecting rod mechanism is carried out. The kinematics relationship of each part under typical working condition was obtained. (3) the crankshaft was replaced by flexible body, and the torsional response of crankshaft system was analyzed by rigid-flexible coupling simulation, and the effect of different rotational speed and load on torsional vibration amplitude of crankshaft was studied. The results show that the torsional vibration of crankshaft tends to increase with the increase of engine speed and load, and the effect of rotating speed on torsional vibration of crankshaft is more obvious. At the same time, the pressure load spectrum of each spindle neck and connecting rod journal in the steady state process of crankshaft is obtained. For further research on the fatigue life of crankshaft, an important load boundary condition (.4) is established in ANSYS to generate the finite element model. The natural frequency and mode shape of the crankshaft are obtained by free mode analysis, and the static strength of the crankshaft is checked according to the limit load obtained by multi-body dynamics simulation. The results show that the static strength of the crankshaft exceeds its use standard. Meet the requirements. Finally, combined with the load spectrum obtained by the multi-body dynamics software and the stress and strain analysis results of the crankshaft obtained by finite element analysis under various working conditions, By fitting the S-N curve of the material, the fatigue life of the crankshaft is predicted. The result of analyzing the cloud diagram of the fatigue life shows that the number of life of the most dangerous part of the crankshaft is 1310. It is considered that the crankshaft will not be damaged by fatigue. The service life of crankshaft is met.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U464.133.2

【相似文献】