摘要曲轴是发动机中最重要、载荷最大的零件之一。曲轴承受着气缸里的气体压力和往复及旋转质量惯性力引起的周期性变化载荷，并对外输出扭矩，理论和实践表明，汽车发动机(中小型发动机)的曲轴的破坏形式主要为弯曲疲劳破坏。因此，在曲轴内产生交变的弯曲应力，可能导致曲轴疲劳失效，而曲轴一旦失效，就可能引起其它零件随之破坏。49741

鉴于曲轴在使用上的重要性，宜使用较先进的计算方法，如有限元方法进行分析，以了解曲轴在设计上是否存在明显的缺陷。传统的多缸机曲轴应力及变形的计算，一般采用连续梁简化模型，但是精度不够高，大型有限元软件应为高精度计算的首选。为此，本文应用Pro/E，对曲轴建立了符合实际情况的三维有限元模型，然后导入ANSYS模拟曲轴真实的边界条件，对曲轴进行模态分析，得出各阶振型和频率，为其结构的改进设计提供了一定参考。

毕业论文关键词:曲轴、有限元、Pro/E、ANSYS

Abstract Crankshaft is the most important part with maximum load in the engine.The crankshaft is under the gas pressure in cylinder and the load with cyclical change resulted by rotating inertia force ,and output the torque outside.Theory and practice indicate that the main damage form of the crankshaft in automotive engine (small and medium engine)is bending fatigue damage.So the initiation of the alternating bending stress in the crankshaft may cause the crankshaft fatigue failure.And once the crankshaft failured,it could cause other parts to be damaged.

In view of the importance of the use of the crankshaft, it is appropriate to use advanced calculation method, such as finite element method , to analysis to understand whether there are design obvious flaw on the crankshaft. The traditional multi-cylinder machine crankshaft stress and deformation calculation usually use continuous beam simplified model, but the precision is not enough. Large finite element software should be the first choice of high accuracy calculation. So this paper use Pro/E to construct a three dimensional finite element model with the actual situation. Then add the model into the ANSYS to simulate real boundary conditions of the crankshaft. Modal analysis is used to obtains each vibration mode and frequency to provide some reference for the design improvement of structure.

Key word: Crankshaft, Finite element,  Pro/E,  ANSYS

目录

第一章  绪论 1

1.1课题背景 1

1.1.1课题来源、目的及意义 1

1.1.2主要研究内容 1

1.2国内外研究现状 2

1.2.1发动机零部件有限元网格生成技术 2

1.2.2汽车发动机中复杂边界条件的确定和施加 2

第二章  有限元及ANSYS简介 4

2.1有限元的发展历史 4

2.2 有限元的基本概念 5

2.3 有限元法的一般程序结构 8

2.4 有限元法的发展趋势 9

第三章曲柄连杆机构受力分析 11

3.1载荷处理 11

3.2边界条件处理 12

3.2.1载荷边界 12

3.2.2 约束边界 14

第四章 基于Pro/E实体建模 15

4.1 实体建模技术研究