谱矩阵试验条件制定方法

On the Derivation method of Spectral Density Matrix Specifications

随着多振动台激励系统和多自由度控制系统设备能力的发展,六自由度随机振动试验方法已被纳入美军标。本文专注于研究多自由度试验系统输入条件的确定,指出两个自由度之间振动的相干度是非常重要的参数,相干为零的独立基础激励未必反映最严重工况,提出了一个广义的六自由度振动条件的制定方法。利用滑动平均将实测信号分解成平稳载波和时变调制波,然后多个载波信号被整合成一个时间序列,通过时平均得到归一化的六自由度参考谱矩阵。虚拟仿真试验结果证明了方法的保真度。

With the development of multiple excitation systems and MDOF vibration control systems,the 6-DOF laboratories vibration test method is brought into MIL-STD.This paper concentrates on the determination of an input specification for such MDOF systems.It is pointed out that the coherent value between two degrees of freedom is a very important parameter.The motion excitation of independent foundation with zero coherence does not necessarily reflect the most serious condition.A generalized 6-DOF vibration specification development technique is proposed.The measured signal is decomposed to the stationary carrier and time-varying modulated wave by the moving average.Then,a lot of carrier is integrated into a time series.The normalized 6-DOF spectral density matrix is obtained by time averaging.Virtual simulation results demonstrate the fidelity of this method.