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热氧老化效应对航天器橡胶密封性能的影响研究

Investigation of Thermo-Oxidative Aging Effects on Sealing Performance of Spacecraft Elastomeric Seals

  • 摘要: 密封性能是航天器橡胶密封系统的关键指标,橡胶材料密封性能的劣化规律直接决定航天器橡胶密封系统的使用寿命。目前,针对橡胶密封性能变化规律的研究多集中于材料宏观接触性能或橡胶材料特定力学性能变化的定性研究,少有基于橡胶密封泄漏通道的泄漏率计算方面的定量研究。文章针对航天器用三元乙丙橡胶材料,基于接触面泄漏通道和分子流气体流动特征构建了微观泄漏模型,泄漏率的理论计算结果得到了测试结果的验证。基于时温等效理论,测试橡胶材料压缩永久变形,并构建热氧老化数学模型以预测橡胶材料的寿命。获得橡胶材料在经过不同条件的热氧老化后的应力−应变本构关系,并将测得的本构关系应用于橡胶密封性能分析的有限元模型中。根据测得的热氧老化前后橡胶材料表面微观形貌,以及计算的接触压力和接触宽度变化情况,建立考虑热氧老化效应的橡胶密封微观泄漏模型。计算不同热氧老化效应影响下橡胶密封的泄漏率,用泄漏率测试结果验证理论计算结果。

     

    Abstract: The sealing performance serves as a critical indicator for spacecraft rubber sealing systems, where the degradation behavior of rubber materials directly determines the service life of these systems. Current research on rubber sealing performance evolution primarily focuses on qualitative studies of macroscopic contact properties or specific mechanical property variations, with limited quantitative investigations on leakage rate calculations based on seal leakage channels. This paper establishes a microscopic leakage model for spacecraft-grade ethylene-propylene-diene monomer (EPDM) rubber by analyzing interfacial leakage channels and molecular flow characteristics of the gas, with theoretical leakage rate calculations validated through experimental measurements. The compression set of rubber materials was tested using time-temperature equivalence theory, and a thermal-oxidative aging mathematical model was developed for lifespan prediction. Stress-strain constitutive relationships were obtained for rubber materials subjected to various thermal-oxidative aging conditions, with the measured relationships incorporated into finite element models for sealing performance analysis. A microscopic leakage model considering thermal-oxidative aging effects was established by analyzing pre-/post-aging surface micro-morphology and calculating contact pressure/width variations. Leakage rates under different thermal-oxidative aging conditions were calculated, with experimental leakage rate measurements validating the theoretical results.

     

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