SU512602A1 - Aperiodic sensor for recording acoustic signals - Google Patents

Description

one

This invention relates to a technique for receiving and exciting ultrasonic elastic waves.

A device for recording acoustic signals is known, consisting of a continuous piezoelectric lane, soldered to a conical waveguide made of brass, placed in a housing and filled with compound, as is an example of epoxy resin.

However, such a device is characterized by the limited range of frequencies of received and excited acoustic waves. In addition, with the help of such a device, we could record without distorting the shape of signals with frequencies lower than where c is the speed of sound in the material of the piezoelectric plate, d is the plate thickness. The bandwidth can be expanded by increasing the thickness of the piezoelectric plate, but the size of the waveguide increases significantly.

The purpose of the invention is to expand the range of recorded frequencies.

This is achieved by the fact that in the proposed aperiodic sensor the waveguide is multi-layered with a concentric arrangement of layers relative to its axis, moreover, the Layer materials are taken with an acoustic impedance equal to the acoustic impedance of the piezoelectric plate and decreases from the layer to the layer towards the waveguide axis the speed of acoustic waves.

The drawing shows the proposed sensor. Aperiodic sensor for registration

acoustic waves consist of a piezoelectric plate 1, a conical waveguide 2 attached to it, made of a multilayer of materials 3, 4, 5, placed in the housing 6 and filled with compound 7.

The sensor works as follows.

When registering acoustic signals on the piezoelectric plate 1 serves an acoustic pulse. As a result of the acoustic pulse passing through the piezoelectric plate on its plates, due to the direct piezoelectric effect, electrical signals appear that are removed from the plates by known means, and the acoustic emulsion enters the tapered waveguide 2. Because the waveguide is made multi-layer with concentric layers of the layers waveguide materials 3, 4, 5, selected so that the acoustic coherence of each layer coincides with the acoustic resistance of the piezoelectric tion plate, and the acoustic velocity of the waves u.menshaets from layer to layer towards the axis of the waveguide. Reflected acoustic waves are focused in the axial

the waveguide layer npii. smaller its length.

Copper, brass and Wood alloy can be used as the waveguide 1 material, which corresponds to the piezoelectric plastics material made of PZT. With this selection, the waveguide lengths are 5 cm. To negate the fraction of reflected signals falling on the piezoelectric plate, the waveguide can be made acoustically insulated by the axial layer from the piezoelectric plate. Moreover, it is possible to vary the performance of a piezoelectric plate with an aperture, which also allows reducing the influence of the scraper on the operation of the sensor.

As a result of this implementation of the aperiodic sensor, the maximum distortion of the waveform is achieved, which leads to

the expansion of the frequency band of the recorded frequencies n, from 10 to 10 MHz.

Claims (1)

Invention Formula Aperiodic sensor for recording acoustic signals, comprising a housing, a piezoelectric plate, a cone-shaped waveguide and a compound different from those that, in order to expand the range of recorded frequencies, the waveguide is multi-layered with a concentric arrangement of the layers relative to its axis, a-bushy impedance equal to the acoustic impedance of the piezoelectric plate, and the speed of the acoustic waves decreasing from layer to layer towards the waveguide axis. I 3 k