Effect of Geometry on Flexural Wave Propagation in a Notched Bar

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Abstract

The propagation of flexural elastic waves in notched metal bars with a rectangular cross section with the depth of notches increasing by a power law has been studied by numerical modeling and experimental laser scanning vibrometry. Three types of notch arrangement have been considered: uniform and more frequent and sparse towards the end of a bar. Such structures exhibit the characteristics of an acoustic black hole. For all the studied samples, in the 10–100 kHz frequency range, an increase in amplitude and decrease in length of the flexural wave have been experimentally found as a wave approaches the end of a bar. It has been shown that there is a critical frequency, above which the modes exhibit a section with highly reduced amplitude of oscillations.

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About the authors

A. A. Agafonov

Lomonosov Moscow State University

Email: aikor42@mail.ru
Russian Federation, Moscow

M. Yu. Izosimova

Lomonosov Moscow State University

Email: aikor42@mail.ru
Russian Federation, Moscow

R. A. Zhostkov

Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences

Email: aikor42@mail.ru
Russian Federation, Moscow

A. I. Kokshaysky

Lomonosov Moscow State University

Email: aikor42@mail.ru
Russian Federation, Moscow

A. I. Korobov

Lomonosov Moscow State University

Author for correspondence.
Email: aikor42@mail.ru
Russian Federation, Moscow

N. I. Odina

Lomonosov Moscow State University

Email: aikor42@mail.ru
Russian Federation, Moscow

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Supplementary files

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2. Fig. 1. General view of the split bar specimens

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3. Fig. 2. Bending mode in sample No. 2 at the frequency of 8.1 kHz

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4. Fig. 3. Distribution of bending wave amplitude along the centre line of the rod surface with envelopes in specimens (a) - No. 1, (b) - No. 2, (c) - No. 3

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5. Fig. 4. Distribution of normalised amplitude along the rod (sample No. 1) at a special frequency (52.9 kHz)

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6. Fig. 5. Bending wave length in the rod as a function of distance: (a) - sample No. 1, (b) - sample No. 2, (c) - sample No. 3

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7. Fig. 6. (a) - Experimental specimens No. 1, 2, 3 and (b) - fixed rod No. 3 for excitation of bending waves in it

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8. Fig. 7. AFC in cut rods with three types of slots arrangement

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9. Fig. 8. Modes of bending waves in samples (a) - No. 1, (b) - No. 2, (c) - No. 3

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10. Fig. 9. Length of the bending wave in a rod with an increased number of slots towards the end as a function of the distance travelled

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11. Fig. 10. Straight lines separating the region of the rod near the end where the wave amplitude is small

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