阅读说明：本技术 一种水声材料去耦特性参数的驻波管测量方法 (Standing wave tube measuring method for decoupling characteristic parameters of underwater acoustic material ) 是由 李水 易燕 于 2021-07-13 设计创作，主要内容包括：本发明公开了一种水声材料去耦特性参数的驻波管测量方法,本方法在低频驻波管中实现水声材料去耦特性参数的测量,通过低频驻波管的独特计、低频激励声源和传感器的集成、电子仪器配置建立了样品去耦特性参数测量系统,提出了100Hz～1000Hz频率范围水声材料去耦特性参数的测量方法,编制自动测量软件,很好地解决了在应用环境条件下低频段测量困难的问题。(The invention discloses a standing wave tube measuring method for decoupling characteristic parameters of an underwater acoustic material, which is characterized in that the measurement of the decoupling characteristic parameters of the underwater acoustic material is realized in a low-frequency standing wave tube, a sample decoupling characteristic parameter measuring system is established through the unique meter of the low-frequency standing wave tube, the integration of a low-frequency excitation sound source and a sensor and the configuration of an electronic instrument, the measuring method for the decoupling characteristic parameters of the underwater acoustic material in the frequency range of 100 Hz-1000 Hz is provided, automatic measuring software is compiled, and the problem that the low-frequency section is difficult to measure under the application environment condition is well solved.)

1. A standing wave tube measuring method for decoupling characteristic parameters of an underwater acoustic material is characterized by comprising the following steps:

step 1, preparing an underwater acoustic decoupling material to be detected into a detected sample with a diameter conforming to the inner diameter of a standing wave pipe;

step 2, opening the standing wave tube, and placing the sample to be measured on the central bracket in the standing wave tube to ensure flatness; starting a mechanical control system and closing the standing wave tube; starting a pressure control system, starting a vacuumizing device to form negative pressure in a standing wave tube, injecting purified water into the standing wave tube by using external atmospheric pressure to a preset height, and pressurizing to a pressure point to be measured;

step 3, starting an electronic instrument and software of the measuring device, selecting a required measuring frequency point according to the measuring requirement, setting an output amplitude value of a signal source of the exciter on a measuring software interface, adjusting the gain and the impedance of the power amplifier, and forming a standing wave field between the piston surface of the exciter and the measured sample;

and 4, if the tested sample is a two-end linear system, the following steps are carried out:

wherein 1 and 2 respectively represent the front and the back of the surface of the measured sample, and 4 impedance components can represent the characteristics of the measured sample and allow any response function to be calculated;

let the impedance matrix of the water layer and the decoupling layer be Z:

wherein the boundary condition of the terminal is p₂＝Z_H·v₂Measuring p₀，v₀And v₂And obtaining Z:

Z＝Z₀·Z₁ (3)

Z₀for the transfer resistance of the aqueous layer, for an equivalent uniform layer, there are

Z₁₁＝Z₂₂ (4)

Z₁₁·Z₂₂-Z₁₂·Z₂₁＝1 (5)

Equation (2) is written as:

p₀＝z₁₁p₂+z₁₂v₂ (6)

v₀＝z₂₁p₂+z₂₂v₂ (7)

obtained from formula (6):

p₂＝Z_H·v₂ (9)

derived from equations (8) and (9):

derived from equations (7) and (9):

derived from equations (4), (5) (10) and (11):

obtained by the formula (3):

Z₁＝Z₀·Z^-1 (15)

setting:

decoupling coefficient:

step 5, if necessary, adjusting different hydrostatic pressures, and repeating the step 4;

step 6, after the measurement is finished, starting a pressure control system, opening a pressure relief valve and releasing the pressure in the standing wave tube; starting a mechanical control system, opening a standing wave tube, and taking out the tested sample.

Technical Field

The invention relates to the technical field of measurement and testing, in particular to a standing wave tube measuring method for decoupling characteristic parameters of an underwater acoustic material.

Background

The main purpose of realizing the sound stealth of the naval vessel is to reduce the reflection of the detection sound wave of the enemy active sonar and reduce the target intensity of the vessel; the radiation noise level of the boat is reduced, and the probability of being monitored and detected by the enemy passive sonar is reduced. The sound-absorbing tile is pasted on the naval vessel shell, which is an effective sound stealth means. According to the report from abroad, the Anechoic Tiles can be divided into Anechoic Tiles (Anechoic Tiles), Decoupling Tiles (Decoupling Tiles) and multifunctional Tiles according to the difference of main functions, and the Anechoic Tiles are respectively used for absorbing the detection sound waves of the enemy active sonar and shielding the radiation of the noise of the boat to the seawater, and the multifunctional Tiles have two functions of sound absorption and Decoupling.

In addition, with the development of underwater acoustic countermeasure technology, the research on novel ship shell sonar technologies such as a submarine broadside array and the like is further promoted, the ship shell sonar is installed on a submarine ship shell platform, the self-noise of the sonar mainly comes from the structural vibration of the submarine platform and equipment, the sound sonar self-noise is reduced, and the method is the primary condition for improving the detection distance of the sonar and improving the detection precision. For example, the broadside array sonar hydrophone module and the mounting platform have strict requirements on vibration isolation, if no vibration isolation measures are provided or the vibration isolation performance is poor, the vibration of the boat shell can seriously affect the performance of the receiving array, the technical indexes of the whole sonar can be greatly reduced, an air/rubber baffle is applied to a certain broadside array sonar array, and a decoupling module is arranged in the broadside array sonar array.

In summary, it is very important to research the decoupling and vibration isolation performance of the sonar array acoustic baffle, the hydrophone module and the mounting members thereof. But in the past we have not been able to make intensive studies in this regard. Since the acoustic and mechanical properties of the underwater acoustic material are very sensitive to frequency and hydrostatic pressure, the importance of the underwater acoustic material is more prominent as the operating frequency of the sonar is reduced and the operating depth is increased. Measuring the acoustic performance of a sample of an underwater acoustic material or member in a frequency band above 100Hz is almost impossible to test in free field. Because the wavelength in water is much larger than the material sample, the edge diffraction and diffraction of the sample severely interferes with the measurement. The underwater acoustic material test of low frequency band generally adopts standing wave tube and travelling wave tube facilities, the minimum working frequency of the standing wave tube and the travelling wave tube facilities is theoretically not limited by the length of the acoustic tube, the measurement requirement can be met only by enough low-frequency signal-to-noise ratio in the tube, and the diameter of a sample is close to the inner diameter of the acoustic tube. When the traveling wave tube measuring device is used for measuring the reflection coefficient and the transmission coefficient of a sample, the front boundary and the rear boundary of the sample are both water media, so that the traveling wave tube measuring device is suitable for evaluating the acoustic performance of the sample, but cannot simulate the layering condition of 'seawater-tile-metal shell-air'. Under the condition that the multifunctional tile or the sound insulation decoupling tile is applied to the submarine shell in China, domestic research on the measurement of decoupling characteristic parameters is less, and a mature measurement method is not available. Due to the requirement traction of model items, it is necessary to establish a nitrogen pressurized low-frequency standing wave sound tube, simulate the layering condition of 'seawater-tile-metal shell-air', and measure the decoupling characteristic parameters of a sample under an air backing.

In order to rapidly and correctly measure various performances of the sound insulation and decoupling tile, various testing methods are researched in the underwater sound tube. The sound field in the underwater sound tube is an ideal plane transition sound field, the required sample is small, the boundary condition is simple, the comparison with a theoretical calculation result is easy, and the method is very suitable for being used as an experimental means in a research process to calculate the radiation sound pressure of the sound field by measuring the sound power of the sound source. We can simply attribute the conditions of acoustic radiation testing to two points: one is no reflection, and the other is plane wave. Both of these are easily implemented in the hydroacoustic tube. In the sound tube waveguide, the sample to be measured should have a plane vibration surface, and the radiated sound wave generated by the excited vibration of the sample propagates in the form of a plane wave in the sound tube. Referring to fig. 3, if the sound-absorbing wedge with excellent performance is arranged at the tail end of the sound tube, no reflection can be achieved. The incident and reflected two columns of waves can be separated using the hydrophone method. And exciting the sample by using a vibration exciter, exciting the sample to vibrate, radiating sound waves into the sound tube, and measuring the stress on the surface of the sample and the sound field in the sound tube by using a force sensor and a hydrophone respectively. When the vibration exciter excites a sample in the underwater sound tube, the excitation frequency is controlled to be lower than the cut-off frequency of the sound tube, so that only plane waves appear in the sound tube. The test pieces are attached to steel backing plates with the same thickness, the sound radiation sound pressure of the sample under excitation of different frequencies is respectively measured, normalization processing is carried out relative to the exciting force, and the sound radiation intensity value of the sample under the action of the same exciting force, namely the force-sound transmission characteristic of the damping structure is obtained. However, this approach has a high low frequency limit because the wedge cannot absorb sound completely in the sub-kilohertz frequency range.

Disclosure of Invention

The invention provides a standing wave tube measuring method for decoupling characteristic parameters of an underwater acoustic material, and aims to solve the problem that low-frequency band measurement is difficult under the application environment condition in the prior art.

In order to solve the technical problems, the invention adopts the following technical scheme:

a standing wave tube measuring method for decoupling characteristic parameters of an underwater acoustic material comprises the following steps:

step 1, preparing an underwater acoustic decoupling material to be detected into a detected sample with a diameter conforming to the inner diameter of a standing wave pipe;

step 2, opening the standing wave tube, and placing the sample to be measured on the central bracket in the standing wave tube to ensure flatness; starting a mechanical control system and closing the standing wave tube; starting a pressure control system, starting a vacuumizing device to form negative pressure in a standing wave tube, injecting purified water into the standing wave tube by using external atmospheric pressure to a preset height, and pressurizing to a pressure point to be measured;

step 3, starting an electronic instrument and software of the measuring device, selecting a required measuring frequency point according to the measuring requirement, setting an output amplitude value of a signal source of the exciter on a measuring software interface, adjusting the gain and the impedance of the power amplifier, and forming a standing wave field between the piston surface of the exciter and the measured sample;

and 4, if the tested sample is a two-end linear system, the following steps are carried out:

wherein 1 and 2 respectively represent the front and the back of the surface of the measured sample, and 4 impedance components can represent the characteristics of the measured sample and allow any response function to be calculated;

let the impedance matrix of the water layer and the decoupling layer be Z:

wherein the boundary condition of the terminal is p₂＝Z_H·v₂Measuring p₀，v₀And v₂And obtaining Z:

Z＝Z₀·Z₁ (3)

Z₀for the transfer resistance of the aqueous layer, for an equivalent uniform layer, there are

Z₁₁＝Z₂₂ (4)

Z₁₁·Z₂₂-Z₁₂·Z₂₁＝1 (5)

Equation (2) is written as:

p₀＝z₁₁p₂+z₁₂v₂ (6)

v₀＝z₂₁p₂+z₂₂v₂ (7)

obtained from formula (6):

p₂＝Z_H·v₂ (9)

derived from equations (8) and (9):

derived from equations (7) and (9):

derived from equations (4), (5) (10) and (11):

obtained by the formula (3):

Z₁＝Z₀·Z^-1 (15)

setting:

decoupling coefficient:

step 5, if necessary, adjusting different hydrostatic pressures, and repeating the step 4;

step 6, after the measurement is finished, starting a pressure control system, opening a pressure relief valve and releasing the pressure in the standing wave tube; starting a mechanical control system, opening a standing wave tube, and taking out the tested sample.

Compared with the prior art, the standing wave tube measuring method for the decoupling characteristic parameters of the underwater acoustic material has the following remarkable advantages:

the invention provides a standing wave tube measuring method of decoupling characteristic parameters of an underwater acoustic material, which is characterized in that the measurement of the decoupling characteristic parameters of the underwater acoustic material is realized in a low-frequency standing wave tube, a sample decoupling characteristic parameter measuring system is established through the unique meter of the low-frequency standing wave tube, the integration of a low-frequency excitation sound source and a sensor and the configuration of an electronic instrument, the measuring method of the decoupling characteristic parameters of the underwater acoustic material in the frequency range of 100 Hz-1000 Hz is provided, automatic measuring software is compiled, and the problem of difficulty in low-frequency section measurement under the application environment condition is well solved.

Drawings

FIG. 1 is a schematic view of a standing wave tube measurement apparatus;

FIG. 2 is a schematic diagram of a plane wave model for decoupling coefficient measurement;

fig. 3 is a schematic diagram of a sound tube measuring system for measuring the force-sound transmission characteristic of an underwater sound material sample.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.

The embodiment of the invention provides a standing wave tube measuring method for decoupling characteristic parameters of an underwater acoustic material, which comprises the following steps:

step 1, preparing an underwater acoustic decoupling material to be detected into a detected sample with a diameter conforming to the inner diameter of a standing wave pipe;

step 2, opening the standing wave tube, and placing the sample to be measured on the central bracket in the standing wave tube to ensure flatness; starting a mechanical control system and closing the standing wave tube; starting a pressure control system, starting a vacuumizing device to form negative pressure in a standing wave tube, injecting purified water into the standing wave tube by using external atmospheric pressure to a preset height, and pressurizing to a pressure point to be measured;

step 3, starting an electronic instrument and software of the measuring device, selecting a required measuring frequency point according to the measuring requirement, setting an output amplitude value of a signal source of the exciter on a measuring software interface, adjusting the gain and the impedance of the power amplifier, and forming a standing wave field between the piston surface of the exciter and the measured sample;

and 4, if the tested sample is a two-end linear system, the following steps are carried out:

wherein 1 and 2 respectively represent the front and the back of the surface of the measured sample, and 4 impedance components can represent the characteristics of the measured sample and allow any response function to be calculated;

let the impedance matrix of the water layer and the decoupling layer be Z:

wherein the boundary condition of the terminal is p₂＝Z_H·v₂Measuring p₀，v₀And v₂And obtaining Z:

Z＝Z₀·Z₁ (3)

Z₀for the transfer resistance of the aqueous layer, for an equivalent uniform layer, there are

Z₁₁＝Z₂₂ (4)

Z₁₁·Z₂₂-Z₁₂·Z₂₁＝1 (5)

Equation (2) is written as:

p₀＝z₁₁p₂+z₁₂v₂ (6)

v₀＝z₂₁p₂+z₂₂v₂ (7)

obtained from formula (6):

p₂＝Z_H·v₂ (9)

derived from equations (8) and (9):

derived from equations (7) and (9):

derived from equations (4), (5) (10) and (11):

obtained by the formula (3):

Z₁＝Z₀·Z^-1 (15)

setting:

decoupling coefficient:

step 5, if necessary, adjusting different hydrostatic pressures, and repeating the step 4;

step 6, after the measurement is finished, starting a pressure control system, opening a pressure relief valve and releasing the pressure in the standing wave tube; starting a mechanical control system, opening a standing wave tube, and taking out the tested sample.

Specifically, the sample in the sound tube is adhered to the backing, the medium in the tube has a multi-layer structure, and a plane wave model composed of the sample to be measured, the front surface water layer and the back surface backing layer is shown in FIG. 2. Height of water layer is H_WAcoustic velocity and density in water are respectively rho_w、c_wThe sound pressure and vibration speed of the water layer on the piston surface are respectively p₀And v₀(ii) a Material sample layer height of H_LThe sound velocity and density in the material are respectively rho_L、c_LThe sound pressure and the vibration speed of the sample layer on the water surface are respectively p₁And v₁(ii) a The height of the backing layer is H_MIn the layer, the sound velocity and the density are respectively rho_M、c_MThe sound pressure and vibration velocity on the backing layer are respectively p₂And v₂. The vibration of the exciter is coupled to the sample through the water medium, the measured sound pressure and acceleration transducer signals are collected by a dynamic signal analysis system under the control of a computer after being conditioned and amplified, and the sound pressure p of the piston surface can be obtained after processing₀Vibration velocity v₀And the vibration velocity v of the rigid backing surface₂Further obtaining the transfer matrix array element of the layered sample and finally obtaining the decoupling coefficient B of the tested sample_V＝v₂/v₁。

The acoustic material acoustic vibration characteristic parameter standing wave tube measuring device (shown in attached figure 1) is applied to the device, so that the measurement of the decoupling coefficient of acoustic material samples such as sound insulation decoupling tiles and the like under the condition of actual use hydrostatic pressure can be realized, and the device is a brand-new acoustic material measuring method and application and is not reported in journal documents at home and abroad. Compared with the traditional method for measuring in the pulse sound tube, the method solves the problem that the low-frequency band measurement is difficult under the application environment condition.

In the description herein, particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore intended that all such changes and modifications as fall within the true spirit and scope of the invention be considered as within the following claims.