机械电子工程专业硕士论文代写：常温低温组合密封结构的有限元分析与优化设计
目录：
摘要 4-5
Abstract 5-6
第1章绪论 9-16
1.1课题背景及研究的目的和意义 9-10
1.2国内外研究现状 10-12
1.3本文组合密封件的工作原理 12-14
1.3.1组合密封件的结构形式 12-13
1.3.2静密封原理 13-14
1.3.3往复动密封原理 14
1.4本文的主要研究内容 14-16
第2章密封材料及实验参数测试 16-25
2.1聚四氟乙烯材料与性能 16-17
2.1.1聚四氟乙烯的结构和特性 16-17
2.1.2聚四氟乙烯的改性 17
2.2橡胶材料与性能 17-19
2.2.1橡胶材料的特点 17-18
2.2.2橡胶超弹性理论 18-19
2.3实验参数测试及数据处理 19-24
2.3.1单轴拉伸 19-20
2.3.2单轴压缩 20
2.3.3平面剪切 20-21
2.3.4实验数据处理 21-24
2.4本章小结 24-25
第3章组合密封结构的有限元数值模拟 25-44
3.1静止工作状态数值模拟 25-35
3.1.1有限元模型的建立 25-26
3.1.2常温下数值模拟 26-31
3.1.3实验验证 31-33
3.1.4低温下数值模拟 33-35
3.2往复工作状态数值模拟 35-43
3.2.1常温下数值模拟 35-37
3.2.2低温下数值模拟 37-39
3.2.3油膜分布的研究 39-41
3.2.4泄漏量的研究 41-43
3.3本章小结 43-44
第4章组合密封结构的优化 44-59
4.1参数对密封性能影响规律的数值模拟研究 44-53
4.1.1工作压力的影响 44-45
4.1.2预压缩量的影响 45-47
4.1.3结构参数的影响 47-53
4.2密封结构优化 53-58
4.2.1优化设计基本概念 53-54
4.2.2组合密封结构的优化 54-56
4.2.3优化前后的对比 56-58
4.3本章小结 58-59
第5章组合密封结构的主要失效形式及影响因素 59-66
5.1主要失效形式 59-60
5.1.1滑环失效 59-60
5.1.2Ｏ形圈失效 60
5.2失效的影响因素 60-64
5.2.1摩擦的影响 60-63
5.2.2加工精度的影响 63
5.2.3温度的影响 63-64
5.3串联密封结构 64-65
5.4本章小结 65-66
结论 66-67
参考文献 67-72
致谢 72
【摘要】 液态火箭发动机对密封的可靠性要求很高,其密封性能的好坏将直接影响整个系统的性能。本文研究的组合密封结构是某型号液态火箭发动机上的动密封装置,其由一个聚四氟乙烯滑环和一个橡胶O形圈组成,要求在常温20℃到低温-40℃的范围内均能保持良好的静、动密封。对此组合密封结构在不同工作环境下的各种工作状态进行有限元模拟研究,可以全面分析此密封结构的密封性能,发现薄弱环节,提高密封可靠性,具有重要的意义。本文首先分析了聚四氟乙烯和橡胶的材料特性,由于橡胶的力学行为不能像金属材料一样简单地用弹性模量来描述,本文通过实验获得了丁腈橡胶在常温(20℃)和低温(-40℃)下的应力应变数据,并利用ANSYS软件拟合得到了此橡胶在常温和低温下的本构方程。建立了组合密封结构的有限元模型,分别对常温和低温两种环境下,组合密封结构的静止工作状态、往复工作状态进行数值模拟研究,获得了应力场、位移场分布及变形情况,全面分析了组合密封结构在不同环境、不同工况下的静、动密封性能。利用流体动力学理论,结合有限元模拟结果,计算出动态油膜厚度,与经验值吻合的很好;由作图法计算出接触区域各点处的油膜厚度,并绘制了油膜分布曲线;从理论上分析了泄漏量的影响因素,为提高密封的可靠性提供了指导。对影响本文密封结构密封性能的工况参数和结构参数进行了有限元数值模拟研究,找出了工作压力、预压缩量、唇前角、唇后角、滑环厚度、唇口偏移量等参数对密封性能的影响规律,并在此基础上对此密封结构进行了优化,得到了最优解。最后分析了组合密封结构的主要失效形式以及影响因素,重点研究了摩擦系数、加工精度、工作温度等对此密封结构失效的影响规律,为此类组合密封结构的设计提供了参考依据。
机械电子工程专业硕士论文代写【Abstract】 It has highly request in seal’s capability and reliability in liquid rocket engine, because the sealing behaviour would influence the whole system. The combined seal in this subject is a kind of dynamic seal in one rocket engine, consisting of one ptfe sliding ring and one O-ring, requested reliable seal at both normal temperature(20℃) and low temperature(-40℃). Finite element analysis about all work conditions of this sealing structure will help to analyze the sealability in the round, find the weakness, optimize the structure, and improve the reliability, which has great significance.Firstly, material property of ptfe and nitrile rubber is analyzed. Because the mechanics behaviour of rubber can not be described simply by modulus of elasticity, stress and strain datas of nitrile rubber are obtained through experiments at 20℃and -40℃. Using finite element software ANSYS, constitutive equations of nitrile rubber at 20℃and -40℃are established.Finite element model of the combined sealing structure is established. After numerical simulation about static work state and reciprocating work state of combined structure at 20℃and -40℃, the stress field, displacement field and deformation of the combined seal is obtained, analyzing the sealing behaviour in all rounds.Based on hydrodynamic theory and resusts of finite element simulation, film thickness calculated is consistent of that of theory. By the method of drawing graph, distribution of film thickness is ploted. Influencing factors to leakage is analyzed in theory, giving guidances to improve the sealing reliability.Simulator investigation is done to the parameters of work condition and structure which influence the sealing behaviour, finding out how working pressure, compression, front angle, back angle, thickness of sliding ring, and offset form the center of O-ring influence the sealing behaviour. Based on this, the sealing structure is optimized, and results of optimization is obtained.In the end of this paper, the failure modality and the factors influencing sealing performance are discussed. The influence of friction, temperatures, and installation accuracy to the failure of the combined seal is selective analyzed. These researches provide comprehensive information for design of this kind of combined sealing structure.
【关键词】 组合密封； 密封性能； 有限元分析； 结构优化；
【Key words】 combined seal； sealing behaviour； finite element analysis； structure optimal design；