橡胶O形圈密封性能的有限元分析

采用ABAQUS有限元分析软件建立O形密封圈的二维轴对称模型,研究预压缩率与介质压力对O形圈VonMises应力、接触应力、接触长度的影响,确定O形圈容易失效的位置,并使用Karaszkiewicz接触公式对有限元分析的结果进行验证。结果表明:O形圈和密封槽转角接触部位容易失效;接触应力呈抛物线分布,接触应力、接触长度随着预压缩率、介质压力增大而增大,有限元计算值与Karaszkiewicz公式计算值较为一致,验证了有限元分析结果的可靠性。     

O形圈材料选择与密封结构设计

O形圈是最常用的密封方式之一。文章对工业产品密封胶料的选用要素进行了详细分析,并对O形圈尺寸的选择、密封沟槽设计、密封配合间隙进行了分析。     

径向单柱塞泵往复密封元件的有限元分析

利用大型通用有限元分析软件ANSYS建立径向单柱塞泵往复密封用O型橡胶密封圈的二维轴对称模型,分析研究O型橡胶密封圈在不同的压缩量和工作油压下的变形和应力分布情况,得出相应情况下的最大范·米塞斯应力、最大接触压力以及最大剪切应力的变化关系.结果表明:上述3种最大应力值都随着压缩量和工作油压的增加而增加,其中最大接触应力值在左右两个主接触面之间呈对称分布,其余两种最大应力值都分布于密封沟槽口附近区域.该结论可以作为今后设计和选择O型橡胶密封圈的依据,同时文中涉及到的处理橡胶类非线性问题的分析方法可以推广到其他不同类型的橡胶密封圈的分析计算.     

Coupled mass diffusion and structural deformation of elastomer seals exposed to rapid gas decompression

A sequentially coupled structural–mass diffusion model has been proposed to evaluate the behaviour of elastomer O-rings exposed to rapid gas decompression in the presence of CO₂. The coupling between mass diffusion and the structural deformation of the O-ring was achieved by employing the Peng–Robinson equation of state and two user-subroutines to evaluate the pressure exerted by the rapidly expanding gas. The finite element analysis (FEA) model has been used to evaluate stress and strain distribution inside the O-ring during rapid gas decompression. It was shown that the nominal stresses go through a stress–state change from compression to tension during the decompression cycle, and the strain rate during the stress–state change is dependent upon the decompression rate. The FEA model revealed that the elements in the centre region of the O-ring's cross-section experience high tensile strains and stresses during each decompression cycle.     

表面粗糙度对橡塑O形圈往复密封性能的影响

建立三维确定性混合润滑数值仿真模型,该模型采用统一Reynolds方程系统法,耦合了固体力学分析、流体力学分析和接触力学分析;生成非高斯粗糙表面,基于混合润滑模型研究表面粗糙度、自相关长度比值和纹理方向对橡塑O形圈往复密封摩擦力、泄漏率、平均膜厚和接触面积比等密封性能的影响规律。研究表明：低速时随着表面粗糙度的增大,润滑区接触面积比增大,引起摩擦因数增大,平均膜厚先增大后减小,临界接触面积比约为40%;在混合润滑状态时,对于横向纹理粗糙表面,存在合适的自相关长度比值使得密封的摩擦因数和接触面积比最低;当纹理方向θ=π/10时,摩擦因数最小。     

深海环境中水下滑翔器密封结构数值分析

为检验水下密封结构的可靠性,利用Ansys Workbench集成平台对有无挡圈配合的O形密封圈的变形和受力情况进行比较分析,并对深水环境中有挡圈配合的O形圈的密封性能进行数值模拟分析。结果表明:在介质压力较大时,有挡圈配合的O形圈可有效防止挤入咬伤,在同样保证密封可靠的条件下最大Von Mises应力可减小20%以上;当介质压力为10 MPa左右时,有挡圈配合的O形圈的最大Von Mises应力有明显的拐点,介质压力大于10 MPa后,O形圈的应力变化趋于平缓,可避免O形圈被破坏导致的密封失效;有挡圈配合的O形圈结构中,起密封作用的是O形圈而非挡圈,挡圈的作用主要是改善O形圈的受力,提高整个密封结构的可靠性。模拟的结果可以说明O形圈配合挡圈提高密封可靠性的原理,为水下密封结构的可靠性检验和密封结构的优化提供了有效的方法。     

On how CO2 partial pressure on corrosion of HNBR rubber O-ring in CO2–H2S–CH4 environment

Effect of CO₂ partial pressure on corrosion of HNBR and FKM rubber O-rings was studied by using a HTHP autoclave and a self-designed O-ring pressure bearing device to simulate the service environment of the packer in the process of associated gas reinjection. Their mechanical properties, EDS and fracture morphology were analyzed. The results showed that as the CO₂ partial pressure increased, the tensile strength, elongation and hardness of the two types of O-rings all decreased. Moreover, the fracture of both O-rings changed from ductile fracture to brittle fracture. In the free-state, the corrosion of the two O-rings in the liquid phase was more serious than in the gas phase. On the contrary, in the compressed state their corrosion in the gas phase was more serious than in the liquid phase. On the whole, the corrosion of the two O-rings in the free-state was more serious than in the compressed state. Their corrosion in CO₂–H₂S environment was influenced by the swelling and chemical reactions of medium molecules. The two O-rings in the compressed state reduced the contact area between O-ring and corrosive medium, resulting in slight corrosion of O-rings under compression. Due to its poor corrosion resistance and the sealing performance, HNBR O-ring had certain risk in the process of associated gas reinjection. FKM O-ring has good corrosion resistance and sealing performance in the CO₂–H₂S environment, so it can be well applied in this environment.     

密封环支撑边界条件对机械密封端面变形的影响

机械密封的密封环是通过辅助O形圈支撑在轴上或者密封腔内，不同的结构设计会改变密封环支撑边界。针对三种机械密封结构模型，利用ANSYS有限元分析软件，模拟机械密封摩擦副端面的变形，讨论了橡胶O形密封圈不同受力边界条件下机械密封端面变形的规律。研究发现当动环、静环均采用SiC时，在静态（结构分析）时，该三种不同支撑结构的摩擦副端面均形成发散间隙，端面变形受支撑边界接触应力的影响较大；热结构耦合分析发现其动环、静环端面间隙呈收敛间隙运转时，热边界条件影响更大。当动环采用石墨，静环采用SiC时，发现其端面间隙可能为收敛型也可能为发散型，这与支撑边界有关。故密封环支撑边界条件的不同会影响动环端面变形，同时动、静环材料的弹性模量对端面的变形有较大影响，从而会影响密封性能。该研究对机械密封设计有指导意义。     

旋转动密封系统中丁腈橡胶O形圈的时效研究

以燃气表中O形圈为研究对象，研究O形圈在旋转动密系统中长效密封性能；从密封机制及特点出发，对O形圈失效机制进行分析。以时间和转速作为研究主要影响因素，以压缩永久变形作为密封性能定量评价指标，进行全面试验与分析，并以二次多项式回归分析获得预测模型并进行试验验证。结果表明：试验用O形圈长期密封性能可靠；使用时间与转速对O形圈压缩永久变形影响均显著，其中使用时间的影响大于转速；转速一定时，时间越长，压缩永久变形越明显，时间相同时，转速越大压缩永久变形越明显。预测模型能够较好地预测不同条件下燃气表旋转动密封性能，可应用于工程实践设计。     

轮式起重机手动操作阀的渗漏研究

本文对当前轮式起重机的手动操作阀存在的渗漏问题，以试验为基础，做多方面的瞬态、稳态试验研究，提出了解决办法，经实践证明，对解决手动操作阀渗漏有较好的效果。