超高速摄影仪转镜谐响应的数值与试验分析

Numerical and experimental analysis of harmonic response of ultra-high speed camera rotating mirror

对超高速摄影仪转镜进行了谐响应数值分析,得到转镜在正弦周期激励下的幅频响应曲线、应力等值线图。转镜的幅频响应曲线在354 Hz处出现峰值,一阶扭转和二阶弯曲共振带出现了叠加,在1 600Hz处曲线有细微的波动,转镜在一阶弯曲共振点处的幅频曲线幅值远大于其在1 600 Hz处的幅值,共振点处的等效应力是其匀速运转时的358倍。在转镜试验测试系统上测得的转镜幅频曲线在297 Hz和355 Hz处均出现了峰值,数值解和实验结果能够很好地吻合。这说明转镜的一阶弯曲固有频率共振带是转镜的危险速度带,一阶弯曲是转镜出现动力学破坏的主要原因。仿真结果与实验结果的一致性表明,利用数值方法预测转镜的设计能否成功克服受迫振动引起的破坏是有效的。

The harmonic response analysis for the rotating mirror of ultra-high speed camera was presented based on the numerical analysis for obtaining the frequency-amplitude characteristic curves and stress contour under the sine excitation.There are two peak values at the 354 Hz and 1 600 Hz in the frequency-amplitude characteristic curves of rotating mirror,but the peak amplitude at 354 Hz is further larger than the other.The resonance zone of the first torsion and bending are repeated.The stress of the first bending is 358 times than the stress of rotating mirror under the uniform speed.Then,rotating mirror experimental analysis was carried out to obtain the frequency-amplitude characteristic curves of rotating mirror through the rotating mirror test system.In the displacement response curves of rotating mirror,a sharp change takes place at the natural frequencies of 297 Hz and 355 Hz.Comparing the results of simulation with that of test,the results of computer simulation agree well with experimental analysis.The results show that the first bending resonance zone is the dangerous speed band of rotating mirror and the first bending is the main reason for dynamical damage of rotating mirror.The results from both the numerical and experimental analysis are consistent and which show that the method is effective by using numerical analysis to predict whether the design of rotating mirror successfully overcome the damage caused by the forced vibration or not.