The evolution of Lamb wave dispersion has a great significance for the characterization of layered materials such as composite plates, bonded joints, and coating materials. The method traditionally used to evaluate locally the dispersion Lamb modes refers to the use of two wide-band transducer in "pitch-catch" disposition. By varying the emitter-receiver at the opposite incidentreflection angle #theta# , and scanning the emission tone-burst frequency f, one distinguishes the minima in the reflectioncoefficient R (f) of the test sample at each #theta# , the dispersion relation of group velocity v_g versus frequency f can be established by v_g chemical bounds v_o/sing #theta# where v_o is the wave velocity in coupling liquid [1-3]. However, there are some inconveniences for this method. Firstly, it needs an ultrasonic goniometer to adjust two probles at a varying oblique incident angle, which is not practical for NDE utilization.
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机译：羊波分散体的演化具有重要意义，对层状材料，如复合板，粘结的接头和涂层材料的表征具有重要意义。传统上用于局部地分散距离leam的方法是指在“间距捕获”配置中的两个宽带换能器的使用。通过在相反的IncidentReflection角度＃theta＃上改变发射极 - 接收器，并扫描发射色调突发频率f，一个区别于每个＃theta＃的测试样本的反射截图R（f）中的最小值，分散关系组速度V_G与频率f可以由V_G化学界限V_O / SING #THETA＃，其中V_O是耦合液中的波速[1-3]。但是，这种方法存在一些不便。首先，它需要超声测筒仪以在不同的倾斜入射角处调整两个覆盖，这对于NDE利用不实用。
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