DFT加速及其在非平稳随机振动计算中的应用

为了降低非平稳随机振动的计算量，采用了离散付立叶变换和线性调频Ｚ变换（ＣＺＴ）。针对工程常用的演变随机激励，将激励的包络和功率谱函数分开处理，这可使理论计算与实测数据相结合，从而克服阻尼难以确定的难点。算例表明，分段ＣＺＴ较普通ＣＺＴ可节约１／３计算量；而平稳的功率谱与包络分开处理也大大节约了计算量并易于工程实际应用。

DFT Accelaration and Its Application in Non stationary Random Vibration Calculation

In order to reduce the burden in calculation of nonstationary random response,the Discret Fourier Transform (DFT) and Chirp Z Transform (CZT) were adoped.Concerning the evolutionary random excitation frequently used in engineering,the nonstationary part (envelop) and the stationery one (spectrum) were processed independently to lessen work.Furthermore,it could build a bridge between theory and measurement,hence the difficulty to handle damping could be avoided.The simulation shows that 1/3 of the calculation amount can be saved in sectional CZT method.The spectrum and envelop splitting technique not only can reduce the computation burden,but also is practicable in engineering application.