航空作动器O形密封材料失效分析

Analysis of material fault of O-ring seal in aircraft cylinder

分析航空作动器往复密封材料的表面磨损失效和疲劳失效,针对材料疲劳失效,提出比S-N曲线更方便实用的基于断裂力学密封疲劳寿命预测方法.由于压缩率与拉伸率对密封失效及寿命的影响极大,分别建立压缩率为8%、12%、16%及20%的二维仿真模型和拉伸率为1、1.03、1.05和1.20的三维仿真模型.通过有限元方法对作动器O形圈进行仿真分析,基于表面磨损失效机理对各模型进行对比分析,获得接触压力与磨损速率的关系.通过基于断裂力学的材料疲劳失效机理,计算O形密封疲劳寿命.综合考虑两种失效分析,选择恰当的压缩率与拉伸率,不仅可以在保证密封效果的同时延长密封件寿命,而且计算数值与航空标准HBZ 4-1995基本一致,从而为制定相关标准提供理论方法.

The failure mechanism of wear and material fatigue of the reciprocating seal for the aircraft cylinder were analyzed.In view of material fatigue failure,a method based on fracture mechanics for fatigue life prediction of the seal was proposed,which was more convenient and practical than the S-N curve.The two-dimensional models under differential compression ratios of 8%、12%、16%、20% respectively and three-dimensional models under differential tensile ratios of 1、1.03、1.05、1.20 respectively were established because the tensile ratio and compression ratio significantly affect the performance of the seal.The O-ring seal was modeled,and its performance was analyzed based on the wear failure mechanism.Then the relationship between contact pressures and wear rates was obtained.The O-ring fatigue life was calculated based on the fracture mechanics of material fatigue failure mechanism.Results from the two methods show that the appropriate compression ratio and tensile rate can provide the better sealing effect and the longer seal life.The calculation results accorded with the aircraft seal standards HBZ 4-1995,which proved that the method is useful for further standards of the seal.