基于FFT-FS频谱细化技术的船模耐波性试验测量信号分析方法研究

针对FFT频率分辨率受限制且精度不高的缺点以及船模对波浪的运动响应频率是低频且窄带的特点,采用FFT-FS方法对测量的运动响应信号在其对应的窄带频段内进行频谱细化获得更细致准确的信号频域特征;通过对该算法的运算量及分析精度的研究表明该算法是一种运算效率高、分析精度高且受信号本身信噪比影响小的频域分析方法;通过对船模运动响应的仿真信号和实测信号的分析表明该算法确实能有效地用于船模耐波性试验测量数据的定量分析。

Study on the analytical method of measured signal based on FFT-FS spectrum subdivision technique of seakeeping test for ship model

The frequency components and spectrum characteristics of ship models motion signals measured in seakeeping test,whose response frequencies are low and in a narrow bandwidth,can not be effectively analyzed by FFT owing to its low frequency resolution.Thus,a method based on FFT-FS was put forward to improve the frequency resolution.The calculation efficiency and analysis precision of FFT-FS were dis-cussed and are presented to be high.The results also show the analysis precision of FFT-FS is less influ-enced by the snr(signal-noise ratio) of the signals.Simulation and test signals of ship model motion re-sponse were analyzed by FFT-FS,and the results show that it is an effectively analytical method in frequency domain and can be applied to analyze measured signals of model seakeeping test.