含浮动花键的直升机超临界轴系自激振动实验研究

Experimental study on self-excited vibration of helicopter supercritical shafting with floating splines

关键词:  自激振动  浮动花键  超临界轴系  内摩擦  润滑状态  配合间隙

Key words:  Self-excited vibration  Floating spline, Supercritical shafting  Internal friction  Grease lubrication state  Fit clearance

摘要:

为避免含浮动花键超临界轴系的研制及工程应用中出现的自激失稳问题，以某型直升机超临界尾水平轴系为研究对象，定性分析了短轴自激振动的产生机理，开展了浮动花键不同状态下的振动稳定性试验。研究表明：内摩擦阻尼力是短轴自激振动的根本原因，其特征频率为短轴一阶固有频率。正常安装状态下，轴系运转平稳，自激振动幅值均在0.1 mm以下。润滑状态越差齿面损伤越严重，无润滑状态自激振动最大幅值为0.9 mm。定位面配合间隙超限会导致自激振动和齿面损伤，花键侧隙一定程度超限仅有齿面损伤，二者均超限时自激振动最大幅值为4.77 mm，极易发生失稳，且自激振动多出现在小载荷状态。实际应用中应加强振动监控，细化花键检查步骤，控制尾轴同轴度，确保工作安全。

Abstract:

In order to avoid self-excited instability during the development and engineering application of supercritical shafting with floating splines， the self-excited vibration mechanism of short shaft was qualitatively analyzed and vibration stability tests of floating splines under different conditions were carried out by taking the supercritical horizontal shafting of a certain helicopter as research object. The results showed that internal friction force was the fundamental cause for self-excited vibration of the short shaft， and its characteristic frequency was the first natural frequency of the short shaft. Under normal installation condition， the shafting operated smoothly， and the amplitude of self-excited vibration was below 0.1 mm. The worse the grease lubrication state was， the more serious the damage of the tooth surface was. The maximum amplitude of self-excited vibration without grease was 0.9 mm. When the fit clearance of the locating surface exceeded the limit， self-excited vibration and tooth surface damage would be caused. When the spline side clearance exceeded the limit to a certain extent， only tooth surface damage would be caused. When both of them exceeded the limit， the maximum amplitude of self-excited vibration was 4.77 mm， which was very prone to instability. Moreover， self-excited vibration mostly occurred under small load. In practical application， vibration monitoring should be strengthened， spline inspection steps should be refined， and coaxiality of tail shaft should be controlled to ensure work safety.