内燃机活塞设计及分析[毕业设计论文].rar

摘 要


汽车市场的激烈竞争，促使生产厂家极大的缩短了产品的开发周期；发动机朝着增压、高功率、轻量化方向的迅速发展，又使研究员更加注重发动机结构的改进。活塞作为发动机的心脏，是一种技术含量比较高的零部件。由于其工作条件恶劣，高的机械负荷和热负荷常常导致活塞销座的开裂、环槽的早期磨损、活塞顶面燃烧室喉口边缘热裂等故障。因此有必要对活塞进行有限元分析计算，掌握活塞热应力和机械应力的分布规律，为活塞的设计提供有力的依据。活塞的设计方法随着社会的不断发展出现了各种先进的设计、试验和工艺手段，如有限元技术在设计上大幅度的提高了活塞的强度；活塞的温度场有限元分析，能非常准确的模拟活塞的实际工作环境温度。使发动机的功率不断的增加，尾气的排放相对以前也得到了较大的改进，提高了设计的效率和科学性。
本文总结了活塞设计的基本规律，利用UG建立活塞的几何模型。考虑了活塞轴对称性，建立了活塞的四分之一有限元模型。采用有限元分析的方法对设计的活塞进行了温度场和热应力的耦合分析，最后对设计的活塞分析后作出评价并获得了合理的结果。结果表明活塞在顶部以热应力为主，在裙部以机械应力为主。作为活塞热负荷评价的重要依据的第一环槽温度在165～215 ，不会因温度过高而影响气环的密封性（活塞用高温润滑油的结胶温度为220 ）。通过对活塞的三维建模和有限元分析的实例体现出计算机辅助工程技术在产品设计初期的优性：即一方面建立了基本的计算机分析模型，对其进行仿真模拟，从而指导产品的设计；另一方面以此为虚拟分析平台并提供一些规范性或经验性的建模参考，同时也为提高了企业在技术上的自主开发及创新能力而奠定基础。


关键词：活塞，温度场，热应力，强度,有限元









ABSTRACT

The great competition of automobile market has urged the factories to shorten the product development time; with the development of turbo,high power and light engine,the researchers have paid more attentions on the structure than the past. The piston with high technology is the critical part of engine.The work condition of the pistion becomes more and more rigorous.Heavy mechanical load and thermal load often lead to breakage such as the pistion pin hoss split,ring groove wear and tear,combustion chamber throat rim thermal fatigue crack,etc.so,FEA should be done in order to find the distribution rule of thermal stress and mechanical stress of the pistion,and provide reference to improveing design pistion.With the development of the society,many advanced design methods ,test methods and technics have appeared.For example,the FEA technique can improve the strength of the designing pistion greatly,the FEA of the pistion’s temperature field can simulate the real of the work condition of the pistion correctly. It makes engine’s power high, exhaust gas greatly improve, the efficiency of the design increase.
This paper summarizes the design of the basic rules of pistion, the text make used of UG to establish the geometric models of pistion . For the symmetry axis of pistion, build up a quarter of a finite element model of the Pistons. The analysis of a temperature and the coupling of heat stress of the Pistons With the finite element methods. The finally we give an eva luation of the Pistons and analysis was a reasonable outcome. The result reveals that the thermal stress is prominent in the piston head,and the mechanical stress is prominent in the skirt of piston. The first groove of Piston’s temperature as an important basis for the eva luation of Piston’s thermal load is 165 to 215 , which does not affect the tightness of the pistion’s ring(pistion’s plastic high-temperature lubricant temperature is 220 ). Through the analysis of the three-dimensional modeling and finite element of pistion ,it shows the superiority of computer-aided engineering technology in the the early product design. On the one hand,it is the establishment of a basic computer model, its simulation, thus guiding the design of the products; On the other hand ;it can provide some normative or empirical modeling reference to virtual platform, and enhance technical development and innovation capacity for the enterprises.


Key words：pistion,Temperature Field,Thermal Stress,Intensity ,FEM



































目 录

中文摘要......................................................................................................Ⅰ
ABSTRACT.................................................................................................Ⅱ
1绪论............................................................................................................1
1.1 概述……………………………………………………………………1
1.2 国内外概况及发展趋势................................................................................1
1.2.1 活塞的结构形式....................................................................................1
1.2.2 国内外的研究状况................................................................................3
1.3 本文研究的内容.........................................................