两轴四框架结构光电稳瞄吊舱减振器谐振频率计算与试验

Resonant frequency calculation and test for damper of two axes four-gimbal EO pod

根据振动理论分析两轴四框架系统选择减振器的要点,对某型直升机内外框架刚性连接的吊舱进行扫频振动试验,测量了谐振频率和谐振点的扫频放大率,绘制了放大率曲线。通过使用放大率曲线计算内外框架刚性连接时系统的三向刚度。并根据减振器刚度值,利用弹簧串联刚度的计算方法计算了使用减振器系统的三向刚度和谐振频率。重新进行试验后,结果表明系统谐振频率和放大率都满足要求。该结构使用减振器的要点是:减振器放大段位于伺服带宽内,系统谐振频率避开外界扰动频率以及放大率应尽可能小。

The selection of the dampers for two axes four-gimbal electro-optical （EO） pod is investigated according to vibration theory. A frequency scanning vibration test was carried out for a helicopter pod whose inner gimbal was connected with the outer gimbal by rigid link. The resonant frequency and amplification factors were measured and the amplification curves were drawn. Using the amplification curves, the stiffness of the rigid link between the inner and outer gimbals of the pod in three direction was calculated. With the stiffness value of the damper, using cascade spring connection calculation method, the three direction rigidity and resonant frequency of the pod were calculated again with damper installed. The pod was tested again and the results indicate that the resonance frequency and amplification factor meet the requirement. It is concluded that three factors shall be considered for the selection of dampers, its amplification range shall be within the servo bandwidth, system resonant frequency shall avoid external disturbance frequency, and amplification factor shall be minimized.