摘   要活塞是柴油机的关键零部件，在柴油机工作过程中起着很关键的作用。在运行过程中，气缸内的燃气压缩燃烧会产生极高的温度，这会使活塞的整体温度都很高并且分布很不均匀，这将导致活塞产生很大的热应力。其次活塞在受到曲柄连杆机构往复运动产生的惯性力和燃烧室高压气体的载荷作用下，活塞会受到持续不断的机械应力，所以活塞的工作环境十分恶劣。因此，对活塞进行有限元分析，了解活塞的热机械应力应变分布,对了解和改善活塞的运行状况具有重要意义。86187

本文建立活塞的三维模型,再将模型导入ANSYS软件进行强度校核。首先根据柴油机厂提供的图纸建立活塞的Pro/E模型，再通过活塞热力学和动力学计算得到示功图和温度变化图等数据，以这些数据作为基础算出有限元分析的边界条件。最后用ANSYS软件对活塞分别在热负荷、机械负荷和耦合的作用下对活塞进行有限元分析。

通过分析活塞的受热受力分布，得到活塞的应力应变分布，从而确定最大应力集中区域,找出工作危险点，以检验柴油机活塞强度是否符合要求。在了解活塞材料强度要求的前提下，得根据有限元分析结果得出柴油机运行中需要注意的问题，为活塞后续的强化设计提供理论依据。

毕业论文关键词：活塞；三维建模；有限元；强度分析

Abstract The piston is one of the key parts of the diesel engine, it plays a very important role in the process of diesel engine。 The high temperature generated by the high pressure gas in the cylinder will cause the temperature of the piston to be high, and the temperature distribution is very uneven, which leads to generate the thermal stress of the piston。 And under the high gas pressure and the reciprocating motion of the piston cycle, the piston will produce mechanical stress。 In fact, the piston is subjected to thermal stress and mechanical stress of the comprehensive role,so the working environment of piston is very bad。 Therefore,it’s of great significance to study the finite element analysis of the piston and the thermal stress and mechanical stress distribution of the piston。 

In this paper, the Pro/E software is used to establish the three-dimensional model of the piston, which will be introduced into the ANSYS to pide the mesh, and then the intensity check is performed after applying the boundary conditions。 First,the diesel engine parameters such as the diagram are obtained by the thermodynamic calculation of the piston。 Then calculating the average temperature and the average heat transfer coefficient which are the boundary condition of the field analysis。 Then ANSYS software will be used on the piston simulates temperature field, respectively in piston thermal load and mechanical load of the piston。 Finally, the stress distribution of the piston under thermal and mechanical coupling process will be analyzed。

Through the analysis of the piston's heat stress distribution and the stress distribution of the piston, the maximum stress can be determined and the area will be found。 It’s aimed to test whether the strength meets the requirements or not。 By understanding the intensity requirement of the piston material, the problem that needs attention in the operation of diesel engine based on the finite element analysis results is obtained, which provides a theoretical basis for the strengthening design of the piston。

Key words: piston;3D modeling;finite element;intensity analysis

目  录

第一章 绪论 1

1。1活塞强度校核研究的背景和意义 1

1。2 活塞强度校核研究的国内外研究现状 1 ANSYS四缸发动机活塞的强度校核:http://www.youerw.com/jixie/lunwen_102314.html