火箭推进

液体火箭发动机金属密封结构工作在严苛的力热耦合环境中,其循环应力-应变行为和棘轮应变累积效应会显著影响密封环的回弹能力和疲劳寿命。基于统一黏塑性理论对其循环使用过程进行数值研究,采用Chaboche非线性随动硬化和饱和型各向同性硬化模型共同描述密封环基体材料的循环力学行为,分析了密封环经历8次循环使用过程中主副密封唇宏观接触合力的演化规律和局部塑性应变累积部位的损伤进程。结果表明:副密封经历循环力热载荷作用后,由于叠加了显著的棘轮应变,残余塑性应变和累积塑性应变远高于主密封,导致其回弹能力衰减快于主密封且疲劳寿命短于主密封,在重复使用过程中不能发挥冗余设计作用。此外,提高的介质压力和预紧力不足均会导致塑性应变的加速累积,进而影响密封环的循环压缩回弹性能和疲劳寿命,应在装配过程中注意控制预紧力。

The metallic seal structure of liquid rocket engine works in the harsh thermo-mechanical coupling environment, and the cyclic stress-strain behavior and ratcheting accumulation effect will significantly affect the rebound ability and fatigue life of the U-E rings. Based on the unified viscoplastic theory, the cyclic mechanical behavior of the sealing ring was numerical studied. The combined strain hardening model was used to describe the cyclic mechanical behaviors of the seal. The total contact force and damage evolution process of the seal during the 8 using cycles were analyzed. The results show that after the secondary seal was subjected to cyclic thermo-mechanical load, significant ratcheting strain was superimposed. The residual plastic strain and cumulative plastic strain are much higher than that of the main seal, which leads to its rebound ability decay faster than that of the main seal and its fatigue life is shorter than that of the main seal. In addition, the increased medium pressure and insufficient preload will lead to the accelerated accumulation of plastic strain, which will affect the cyclic compression rebound performance and fatigue life of the seal ring.

引言
1 统一黏塑性理论
2 有限元分析
3 结论

图1 金属U-E密封几何图示<br/>Fig.1 Geometric diagram for metallic U-E seal

图1 金属U-E密封几何图示
Fig.1 Geometric diagram for metallic U-E seal

图2 金属密封法兰载荷图<br/>Fig.2 Schematic of loads for metallic seal and flange

图2 金属密封法兰载荷图
Fig.2 Schematic of loads for metallic seal and flange

表1 U-E密封环材料Chaboche模型参数<br/>Tab.1 Chaboche model parameters for the material of U-E rings

表1 U-E密封环材料Chaboche模型参数
Tab.1 Chaboche model parameters for the material of U-E rings

表2 法兰材料性能参数<br/>Tab.2 Material properties of flange

表2 法兰材料性能参数
Tab.2 Material properties of flange

图3 副密封轴向接触合力随循环加载历程的变化<br/>Fig.3 Axial contact force of secondary seal during cyclic loading procedure

图3 副密封轴向接触合力随循环加载历程的变化
Fig.3 Axial contact force of secondary seal during cyclic loading procedure

图4 主密封轴向接触合力随循环加载历程的变化<br/>Fig.4 Axial contact force of main seal during cyclic loading procedure

图4 主密封轴向接触合力随循环加载历程的变化
Fig.4 Axial contact force of main seal during cyclic loading procedure

图5 副密封悬臂根部危险部位径向应力-应变滞回曲线<br/>Fig.5 Radial stress-strain hysteresis curve at the critical site in cantilever root of secondary seal

图5 副密封悬臂根部危险部位径向应力-应变滞回曲线
Fig.5 Radial stress-strain hysteresis curve at the critical site in cantilever root of secondary seal

图6 主密封悬臂根部危险部位径向应力-应变滞回曲线<br/>Fig.6 Radial stress-strain hysteresis curve at the critical site in cantilever root of main seal

图6 主密封悬臂根部危险部位径向应力-应变滞回曲线
Fig.6 Radial stress-strain hysteresis curve at the critical site in cantilever root of main seal

图7 副密封悬臂根部局部塑性应变随循环加载历程的累积<br/>Fig.7 Local plastic strain of the critical site in the secondary seal during cyclic loading procedure

图7 副密封悬臂根部局部塑性应变随循环加载历程的累积
Fig.7 Local plastic strain of the critical site in the secondary seal during cyclic loading procedure

图8 主密封悬臂根部局部塑性应变随循环加载历程的累积<br/>Fig.8 Local plastic strain of the critical site in the main seal during cyclic loading procedure

图8 主密封悬臂根部局部塑性应变随循环加载历程的累积
Fig.8 Local plastic strain of the critical site in the main seal during cyclic loading procedure

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备注

引言

1 统一黏塑性理论

2 有限元分析

3 结论

期刊信息