M −sequence correlation method is applied to the measurement of flexural wave propa − gation in a plate. Transfer fun6tion G ( s) between two points in a wave propagating system 玉 s considered . If G ( s ) has the form of ( 5 ) , the relatiQn between input and output s 量 gnals is derived as ( 6), and group delay τ gd and amplitude coefficient kd can be measured by M ・ sequence correlation 皿 ethod as ( 14 ) . Experiments were performed to measure the flexural wave on a long thin steel strip and

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... wo wave components were obtained as shown in F 茎 g .2. The group velocity of the fast wave component is plotted in Fig. 3, which can be exp 里 ained by convent 三 Qnal Qne dimensional beam theory . To explain the slow 「 wave component , flexural wave propagation in a two dimensionaI plate was analysed . General solution ( 17 ) of the wave equation was assl ユ med and parame − ters in it were determined from free edge boundary conditions . Characteristic equation ( 25)was derived by assuming the presence of non − zero solution and 圭 t was solved by an electronic computer . There exist two kinds of waves , one is the zeroth order wave which is shown in Fig,7and the other ls the first order shown in Fig.1G. The zeroth order wave consists from infinite components O1, 02,03 ... , and the first order wave is very similar to the wave obtained by one dimensional conventional beam theory . From group velocities , mode shapes and cutoff frequencies it is supposed that the fast wave colnponent measured in experiments is the first order wave and the slow wave component is the O2 0rder wave . 1.緒