窄频带Lamb波频散特性研究

利用连续小波变换对从铝合金板结构中俘获的Lamb波信号进行分析，获得波信号在时间-尺度域的等高线和等高线脊线.根据Lamb波的频散特征、时间-尺度域等高线脊线的斜率和波在不同尺度下的到达时间，识别了Lamb波信号中各信息包的模式，并匹配出基础阶模式窄频带Lamb波在铝合金板结构中传播的实际频散曲线.对试验的Lamb波信号分析的结果表明该方法对于研究和应用窄频带Lamb波的频散特性是有效的. 关键词： 连续小波变换 Lamb波 频散

Dispersion analysis of Lamb waves with narrow frequency bands

Dispersion is the intrinsic characteristic of Lamb waves, which influences the effective applications of Lamb waves in plate-like structures. The continuous wavelet transform (CWT) was applied to the Lamb wave signals with narrow frequency band captured from aluminium structures. The CWT-based contour and ridge were therefore searched in the time-scale domain. The unavoidable dispersion characteristic was used in this paper to distinguish the mode of each wave package and pinpoint these packages at each scale for determining the actual group velocities of dispersion curves. Analysis results demonstrate that the proposed approach is effective in dispersion analysis and wave mode differentiation.