摘要柴油机活塞是柴油机燃烧室的重要组成部分，是实现燃料燃烧所释放的热能转化 为机械能的重要媒介。因此，活塞在机械负荷与热负荷的共同作用下容易产生机械应 力和热应力。活塞组的设计对于柴油机的使用寿命、可靠性及其性能的作用是极为重 要的。如今，随着柴油机向着增压、强化的方向发展，提高柴油机活塞的强度以应对 更大的机械负荷与热负荷已经引起了人们的重视。柴油机活塞组的设计与强度校核旨 在通过有限元分析软件对活塞进行数值模拟，从而找出活塞需要强化的部位，实现其 性能的改善。 84551

本设计首先通过所给定的设计参数参阅《柴油机设计手册》等资料进行设计计算， 再绘制出 CAD 图纸；在此基础上利用 SolidWorks 建模软件建立活塞的三维模型；最 后使用 SolidWorks 中的 Simulation 模块对所建立的活塞模型进行强度校核，而活塞的 热边界条件的确定是本设计的所需要解决的难题。考虑到活塞各组件的接触关系，分 析了螺钉的预紧力、热负荷、爆发压力多场耦合作用下的应力场和位移场的分布情况， 为优化设计提供了参考。 

由活塞温度场分析结果可知，活塞最高温度位于活塞顶端。又由于热应力的集中， 最高温度集中在活塞头顶部的边缘位置。通过分析活塞受力情况和受热情况以及热- 机耦合情况，得出活塞内部的应力和变形分布，确定活塞内部形变主要是热负荷所致。 应力集中主要是机械负荷导致，分布在环形冷却腔靠近活塞头与活塞杆连接面的一侧 与振荡冷却孔的交汇处。在冲击载荷的作用下，活塞预紧力越大，则疲劳寿命所受影 响越显著。因此需要确定活塞在受到热-机耦合载荷时出现应力集中的地方，关注活 塞与气缸缸套之间的装配间隙，螺栓预紧力等对活塞工作可靠性的影响，为柴油机进 一步优化设计提供有力的依据。 

毕业论文关键字：柴油机活塞，有限元，热负荷-机械负荷耦合，应力，温度场 

Abstract Diesel Engine Piston is an important part of the combustion chamber of Diesel Engine, and it is an important medium to realize the conversion of heat energy released by the combustion of the fuel into mechanical energy。 Therefore, the piston is prone to mechanical stress and thermal stress in the joint action of thermal and mechanical load。 The design of the piston assembly is very important for the service life, reliability and performance of the Diesel Engine。 Nowadays, with the development of the Diesel Engine in the direction of increasing pressure and strengthening, increasing the strength of the piston of Diesel Engine in order to deal with the greater mechanical load and thermal load has attracted people's attention。 The design and strength check of the Diesel Engine Piston group means to conduct the numerical simulation on the piston model through some finite element analysis software, so as to find out the position of the piston that needs to be strengthened。 On this basis, we would bring improvement to the Diesel Engine 。

At first , we have to ensure the relative dimension data in the design with the help of the given reference such as “ Designing Manual Of The Diesel Engine” 。 Then we will establish the CAD drawings。 After these preparations, I’ll establish the 3-dimensional model of the piston with the help of Solidworks。 At last, I’ll check the strength of the piston by the flow simulation module in SolidWorks。 But the determination of the thermal boundary condition of the piston is a difficult problem to be solved in the design。 Considering the contact between the piston components, I’ll analyse the pre-tightening force, screw heat load and pressure under multi field coupling of stress field and displacement field distribution, providing a reference for the optimization design。