SU1343342A1 - Chamber for measuring acoustic impedance of materials - Google Patents

Abstract

The invention relates to the field of acoustics, in particular to the testing of materials of vibration-proofing and vibration-absorbing devices. The aim of the invention is to improve the accuracy of measurement and to expand the scope of application by eliminating systematic and random errors and enabling measurements at various pressures. The chamber chamber is made with a smooth inner dome-shaped surface with a hole in the upper part, air bubbles from the liquid float free and are removed from the liquid through the hole in the cap. Air bubbles left in the liquid are compressed and dissolve in it as the pressure changes. In this way, the effect on the measurement of bubbles is eliminated. Having a variable pressure source with a system of regulating elements allows measurement at various pressures. 1 il., 1 s.p. f-ly. with s (L with 4; 00 with 4

Description

The invention of O l is related to the field of acoustics, in conjunction with the testing of materials of vibro-emitting and vibration absorbing devices.

The aim of the invention is to improve the accuracy of measurement and the expansion of the field of application by eliminating systematic and random errors and ensuring the possibility of carrying out measurements at different pressures and expanding the field of application.

H; i the drawing shows the device, a general view.

The chamber for acoustic measurement of the impedance of materials contains a hollow body 1, a cover 2 with a smooth surface with a sliding surface with a hole in the upper part, a piston 3 separating the chamber into two hermetic cavities — front with space (ent; 1 1 and in HP.U a sound receiver 4 (hydrophone) and a material sample under test and an air source with an emitter installed in it on shock absorbers (electrodynamic type vibrator) 5 with piston position sensors 6 and piston vibration sensors 7, variable pressure source 8 Oud, partially filled with liquid, connected to contiguity with liquid and air cavities K (i-measures, guards 9 variable 11 th gyrnshn, adjusting element (metering unit) iO, stop valves ll-16j cylinder G / high pressure air (BBA) and pressure gauge 18.

The camera works as follows.

After (Е 3ano.THeHv; H through the valve 1 3 of the chamber with liquid, nagrimer with water, the air bubbles contained in it are freely exhausted by HBVc. T and are removed from the volume of the fluid cavity, including from all vertical connecting gaps, ne) x interfere along the inner smooth spherical surface of the lid 2 and are removed through the verst located at the top of the lid, after 4ei o the hole is closed with the help of the valve 14.

By opening the valve 16 to the cylinder 7 of the high pressure gages in the chamber, the required static pressure is established by the pressure gauge 18 by means of a source 8 of irregular pressure, filled out as a vessel. partially filled with liquid. With increasing hydrostatic pressure in the fluid cavity

chambers partially left after air removal, air bubbles are compressed and dissolved in a liquid. After installing Tpe6yef) Oio pressure valve 16 closes. To eliminate the effect on the experiment of air, which is in the cavity of the source 8 of variable pressure, the valves 12 are closed.

and

The piston 3 under the action of its own weight and the force of the pressure of the liquid column is lowered onto the lower limiter 9; as evidenced by the lowering of the bottom contacts of the sensor 6 of the position of the piston 3. To bring the moving system of the vibrator into the neutral working position, liquid is taken from the chamber

10 allowing one to vary the hydrostatic pressure in the liquid chamber in small limits and with great accuracy. Due to the resulting pressure difference in the cavity

the camera is required displacement of the piston 3, the presence of the piston 3 in the neutron; 1ln the working position necessary to ensure the vibrator performance,

Solve the lower and upper contacts of the 6 nolc Keny sensor.

Electrodynamic vibrator 5 installed in the air cavity of the chamber transmits /. Oscillations to the associated

With piston 3, interacting with the fluid, it generates sound vibrations in it. Voltage ratios (in amplitude and phase) from sensor 7 of vibration U and from hydrophone 4 of the UQ camera are measured when the sample is filled and ei o absent.

The complex compressibility of a sample of a material is determined by the formula

Claims (1)

1. A camera for measuring the acoustic impedance of materials, comprising a rigid hollow body with a lid, an emitter and a sound receiver, that is, so that, in order to improve measurement accuracy and expand the field of application, it is equipped with a piston that separates it two sealed cavities, a liquid one designed to install a sample of the material and a receiver, and the radiator connected to the piston, the piston's position and vibration sensors and a source of variable pressure, made in the form of a vessel, partially filled th liquid, and connected respectively with liquid and air cavities, and as a sound emitter used electrodynamic type vibrator. 2, the chamber pop. 1, characterized in that the roof is made with a smooth inner surface of a dome-shaped form with a hole in the upper part. iZ Editor N.Egorova Make up. I. Ardyshev Tehred And Didzh Corrector L. Patay Order 4818/46 Circulation 776 Subscription VPNIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d, 4/5 Manufacturing (; tnenno-polygraphic; e enterprise, Uzhgorod, Pr. Pr (yektna, A.