Peculiarities of Flexural Wave Propagation in a Notched Bar

We present the results of numerical simulation and experimental studies of the propagation of fle-xural elastic waves in a notched metal bar with a rectangular cross section that approximates the acoustic black hole effect. The sample is a notched bar; the depth of notches increases according to a power law with an exponent of 4/3. The experimental results and the results of numerical simulation confirm that such bars slow the propagation velocity of an elastic wave towards the end of the bar. It is demonstrated that flexural waves in such structures exhibit dispersion and their amplitude at the end of the bar for some eigenfrequencies is higher than that in a solid bar. The eigenmode shapes of a solid and notched bar are compared together with the distribution of the flexural wave amplitude along the bars. The frequency dependence of the flexural wave length is studied during wave propagation towards the end of the notched bar.