以一组混凝土中实测的爆炸波信号为例,分别采用短时Fourier变换(STFT)、连续小波变换(CWT)和Wigner-Ville分布(WVD)定量分析爆炸波信号的时频能分布和特征,并比较3种方法对非平稳爆炸波信号的适应性,计算出时频谱上不同区域的爆炸波能量。结果表明,爆炸波信号在整个时频能分布图上存在2个区域:一区(3~9μs,19~720 kHz)和二区(14~25μs,19~150 kHz)。两区能量密度明显不同:一区具有高频、高能量密度、作用时间极短和能量大的特点;二区频率和能量密度相对较低,作用时间较长和能量较大。Wigner-Ville分布较其他方法能够适应爆炸波的高、低频分辨率和能量计算精度要求,由该方法得到一区能量占总能量的54.5%,二区占29%。
Blast wave signal measured in a set of concrete was analyzed using short time Fourier transform (STFT), continuous wavelet transform(CWT) and Wigner-Ville distribution(WVD). Then the distribution and characteristics of energy density of blast wave were obtained quantitatively by time-frequency analysis. And the adaptability of the three methods to analyze non-stationary blast wave signals was compared and the blast wave energy of different regions was calculated on the time-frequency spectrum. The results show that the blast wave signal in the whole time-frequency map shows two zones, i.e.(3 - 9 ~ts, 19 - 720 kHz) and (14 - 25 ~ts, 19 - 150 kHz), and the energy density of the two zones is significantly different. The first zone has the characteristics of high-frequency, high energy density, very short duration of action and significant energy, while the second zone has relatively low frequency and energy density, a longer duration of action and larger energy. WVD is more adaptive to the high and low frequency resolution of blast wave and the precision of energy calculation than the other methods. The energy of the first zone is 54.5% of the total energy, and the second zone accounts for 29% by using the WVD method.