液压密封圈有限元分析与研究

发布时间：2018-05-16 03:13

本文选题：密封圈 + 失效　；参考：《天津理工大学》2012年硕士论文

【摘要】：密封圈是液压系统防止泄漏，提高容积效率，保证系统正常工作的重要元件，现代液压控制技术对密封提出了更高的要求。本文分析了密封圈在工作中失效的原因及形式；采用有限元方法建立了不同截面形状的密封圈的仿真模型，对其密封性能进行模拟，分析中考虑了几何非线性、材料非线性、状态非线性；研究了影响密封圈密封性能的因素，提出了结构优化方案；对液压密封圈温度场和热应力耦合场进行分析，探讨了生热对密封性能的影响。研究内容和所得结论如下： 1、Yx形密封圈有限元分析。应用超弹性理论和非线性理论，对Yx形液压密封圈的性能进行模拟，分析了其失效的位置和模式，研究了参数对密封性能的影响，提出了结构优化模型。研究表明：最大应力出现在上下唇交汇处；变形最大区域发生在Yx形开口靠近内唇处；根部有较大的接触压力，根据失效准则，这两处容易发生失效。压力增大时，剪应力明显增加；最大接触压力随介质压力呈线性增长。最大变形随初始压缩率的增加而线性增大，最大剪应力在压缩率为20%时达到最大。槽口圆角半径对Yx形密封圈密封性能的影响很小。摩擦系数增大时，最大剪切应力明显增加，但最大变形和最大接触压力都有减小的趋势。由此提出结构优化方案，并对其进行分析，结果表明接触宽度明显减小，根部磨损得到改善，摩擦减小，可以提高密封圈的使用寿命。 2、O形密封圈仿真分析。分析表明：O形密封圈根部、密封圈和活塞接触部位附近变形较大，最大Mises应力发生在根部。介质压力增加时，密封圈最大变形和等效应力明显增大，接触应力线性增加；初始压缩率增大时变形、剪切应力、Mises应力、最大接触应力随之增加；摩擦系数增大使接触应力和Mises应力增大。因此应选择合适的压缩率，为防止压力增大时根部发生间隙咬伤，加入挡圈，以避免密封槽口处出现应力集中，提高密封圈使用寿命。 3、对O形和Yx形密封圈温度场进行分析。应用传热学原理，分析了橡胶密封圈摩擦生热和机械滞后生热的机理，对密封圈温度场进行分析。由于橡胶材料的导热性差，密封圈在工作过程中温升的热源有两个：摩擦生热和机械滞后生热。摩擦生热主要使密封圈与活塞杆接触部分温度升高，，机械滞后生热使密封圈中心部分温度较高，其温升明显高于摩擦引起的温升；两种热源下，密封圈具有很高的温度场；油压、相对滑动速度以及油温的增大，均使密封圈温升明显增加。因此限制工作压力和相对滑动速度以及较好散热条件，提高密封性能和使用寿命有利。 4、对密封圈的温度-结构进行耦合分析。温度升高时，橡胶硬度下降，密封圈最大剪切应力和接触应力相应减小，而最大等效Mises应力明显减小。同时由于高温容易发生氧化现象，使材料老化加速，导致橡胶材料的硬度、超弹特性、抵抗张力的强度明显减弱，且容易发生永久变形。因此应保证密封圈在一定温度范围内工作。
[Abstract]:The seal ring is an important component of the hydraulic system to prevent leakage , improve the volumetric efficiency and ensure the normal operation of the system .
The simulation model of the seal ring with different cross - section shapes is established by the finite element method . The sealing performance is simulated . The geometric nonlinearity , material nonlinearity and state nonlinearity are considered in the analysis .
The factors influencing the sealing performance of sealing ring are studied , and the structure optimization scheme is put forward .
The temperature field and thermal stress coupling field of the hydraulic seal ring are analyzed , and the influence of heat generation on the sealing performance is discussed . The results are as follows :

1 . Finite element analysis of Yx - shaped sealing ring .

The performance of Yx - shaped hydraulic seal ring is simulated by using super elastic theory and nonlinear theory , the position and mode of its failure are analyzed , the influence of parameters on the sealing performance is studied , and the structural optimization model is proposed .

The results show that the maximum stress appears at the intersection of upper and lower lip ;
the deformation maximum area occurs near the inner lip of the Yx - shaped opening ;
There is a large contact pressure at the root , according to the failure criterion , the two parts are prone to failure . When the pressure increases , the shear stress increases obviously ;
The maximum shear stress increases linearly with the increase of the initial compression ratio . The maximum shear stress reaches the maximum when the compression ratio is 20 % . When the friction coefficient increases , the maximum shear stress increases obviously , but the maximum deformation and the maximum contact pressure decrease . The results show that the contact width is obviously reduced , the root wear is improved , the friction is reduced , and the service life of the sealing ring can be prolonged .

2 . Simulation analysis of O - ring seal ring .

The results show that the deformation of the root of O - ring seal ring , the sealing ring and the contact area of the piston is large , and the maximum von stress occurs at the root . When the medium pressure increases , the maximum deformation and the equal effect force of the sealing ring are obviously increased , and the contact stress increases linearly ;
When the initial compression rate is increased , the deformation , shear stress , von mises stress and the maximum contact stress are increased .
Therefore , the proper compression ratio should be selected to prevent the gap between the root and the retaining ring when the pressure is increased , so as to avoid the stress concentration at the sealing notch and prolong the service life of the sealing ring .

3 . The temperature field of O - shaped and Yx - shaped sealing rings is analyzed .

Based on the principle of heat transfer , the mechanism of friction heat generation and mechanical hysteresis heat generation of rubber seal ring is analyzed . The temperature field of sealing ring is analyzed . Due to poor thermal conductivity of rubber material , there are two heat sources of temperature rise in the sealing ring during operation : frictional heat generation and mechanical hysteresis heat generation . The friction heat generation mainly causes the temperature of the sealing ring and piston rod to rise , the temperature of the central part of the sealing ring is higher than the temperature rise caused by friction .
Under the two heat sources , the sealing ring has a very high temperature field ;
The oil pressure , relative sliding speed and the increase of oil temperature increase the temperature rise of the sealing ring , thus limiting the working pressure and relative sliding speed and better heat dissipation conditions , and improving the sealing performance and the service life .

4 . When the temperature is raised , the rubber hardness decreases , the maximum shear stress and the contact stress of the sealing ring decrease correspondingly , while the maximum equivalent von stress is obviously reduced . At the same time , because of the easy oxidation phenomenon at high temperature , the material aging is accelerated , the strength of the rubber material is obviously weakened , and the permanent deformation is easy to occur . Therefore , the sealing ring should be ensured to work within a certain temperature range .

【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH136

【参考文献】