CN105509873A - Backing-independent type acoustic impedance test method for acoustic coating - Google Patents

Abstract

The invention discloses a backing-independent type acoustic impedance test method for an acoustic coating. An acoustic coating sample is placed at the intermediate position of the tube body of a water-filled impedance tube, and a liquid column of a certain height is ensured on both the upper surface and the lower surface of the acoustic coating sample. One end of the tube cavity of the water-filled impedance tube is internally provided with a projecting transducer. Two hydrophones are arranged in the liquid columns on the upper surface and the lower surface of the acoustic coating sample, respectively. The four hydrophones are respectively connected with a data acquisition instrument. The data acquisition instrument is connected with a measurement control computer. The projecting transducer is driven to launch a stabilized broadband white-noise signal. The data acquisition instrument acquires the acoustic pressures of the hydrophones at the same time and stores the acquired acoustic pressures as a data file. The height of the upper liquid column is changed, and then the data of the acoustic pressures are measured and stored again. After that, the stored data of the acoustic pressures are read, and then the input acoustic impedance and the transmission acoustic impedance of the acoustic coating sample are calculated according to a corresponding equation. According to the technical scheme of the invention, the low-and medium-frequency test accuracy is ensured independent of a backing. Meanwhile, the backing can be re-stuck without taking out the sample. Therefore, the measurement process is simplified, and the measurement efficiency is improved.

Description

A kind of acoustic stimulation sound impedance test method not relying on backing

Technical field

The invention belongs to underwater sound technical field of measurement and test, is a kind of acoustic stimulation input acoustic impedance and the method for testing transmitting acoustic impedance.

Background technology

The acoustical behavior of objective, Validity Test acoustic stimulation is the important component part of acoustic stimulation development, is also the basic foundation of acoustic stimulation effect assessment.Acoustic impedance performance is the important parameter of acoustic stimulation acoustical behavior, can be forecast the acoustical absorption coefficient of underwater sound overlayer under different application operating mode by the acoustic impedance performance of testing acoustic stimulation, and can the structure noise reduction harmony target strength characteristic of laying acoustic stimulation be forecast.

Three levels roughly be experienced by the understanding that the acoustical behavior of acoustic stimulation is tested both at home and abroad, first level mainly tests acoustical absorption coefficient and the reflection coefficient of acoustic stimulation, and assess acoustic stimulation action effect with this, its major defect is that test result affects clearly by backing, causes the actual acoustic situation that accurately can not reflect its application structure; Second level mainly tests the impedance of acoustic stimulation face, and with this derive reflection coefficient and acoustical absorption coefficient and then assess its action effect, but face impedance may be used for solving acoustic target strength problem can not be used for solving structure acoustic radiation problem; The input acoustic impedance of third layer time main test acoustic stimulation and transmission acoustic impedance, this acoustic impedance parameter is the build-in attribute of acoustic stimulation, has nothing to do, and can be used for solving acoustic target intensity and Acoustic Radiation Problems with backing characteristic.

For the measurement of the first level and the second level, shipbuilding industry standard C B/T3674-1995 " underwater acoustic materials standing wave tube measuring method " elaborates measuring material acoustical absorption coefficient in hydroacoustic standing-wave pipe, related description has been carried out in opposite impedance measurement, and illustrates the conversion relation of face impedance and acoustical absorption coefficient; In addition, give also the assay method and the conversion relation that utilize air standing wave tube to carry out acoustical absorption coefficient and acoustic stimulation surface acoustic impedance in GB GB/T18696.2-2002 " in acoustic impedance pipe the measurement part 2 of acoustical absorption coefficient and acoustic impedance: transfer function method ".

For the measurement that third layer is secondary, domesticly delivered correlative theses, set forth the input acoustic impedance of acoustic stimulation and transmit the method and apparatus of acoustic impedance, its method main thought utilizes steel backing to serve as a contrast to apply ointment or plaster at the acoustic stimulation back side, to cause impedance to block, thus meet impedance measurement condition.But just backing often finite thickness, can not meet impedance blocking condition in medium and low frequency section, cause measurement result to there is error; On the other hand, existing measuring method needs applied ointment or plaster respectively in acoustic stimulation two sides firm backing and carry out twice test, the slightly aobvious trouble of test process.

Summary of the invention

The present invention proposes a kind of acoustic stimulation sound impedance test method not relying on backing, object is the precision not relying on backing thus ensure medium and low frequency test, and does not need to take out sample and again paste backing.

Technical scheme of the present invention is as follows:

Do not rely on an acoustic stimulation sound impedance test method for backing, comprise the steps:

Step one, acoustic stimulation sample is placed in the body centre position of underwater sound plane sound wave conduit, ensure that two face side of acoustic stimulation sample have fluid column, in the body chamber of described underwater sound plane sound wave conduit, one end is provided with transmitting transducer, the first nautical receiving set and the second nautical receiving set is provided with in the fluid column of described acoustic stimulation sample first surface side, the 3rd nautical receiving set and the 4th nautical receiving set is provided with in fluid column between acoustic stimulation sample second surface side and transmitting transducer, wherein the first nautical receiving set and acoustic stimulation sample first surface spacing are greater than the second nautical receiving set and acoustic stimulation sample first surface spacing, 4th nautical receiving set and acoustic stimulation sample second surface spacing are greater than the 4th nautical receiving set and acoustic stimulation sample second surface spacing, described each nautical receiving set is connected with data collecting instrument respectively, described data collecting instrument is connected with Survey control computer,

Step 2, drives described transmitting transducer to launch and stablizes wideband white noise signal;

Step 3, described data collecting instrument gathers the acoustic pressure P of first to fourth nautical receiving set simultaneously ₁~ P ₄, save as data file;

Step 4, reads acoustic pressure data document, and calculates the pressure and particle velocity on acoustic stimulation sample first and second surface according to the following formula:

$\begin{array}{c}{p}_u=P_1{\mathrm{coskh}}_1-{\mathrm{sinkh}}_1\frac{P_1{\mathrm{coskd}}_1-P_2}{{\mathrm{sinkd}}_1}\\ v_u=-i\frac{{\mathrm{sinkh}}_1}{\mathrm{\ρ}c}{P}_1-{\mathrm{icoskh}}_1\frac{P_1{\mathrm{coskd}}_1-P_2}{{\mathrm{\ρcsinkd}}_1}\\ p_d=P_3{\mathrm{coskh}}_2+{\mathrm{sinkh}}_2\frac{P_3{\mathrm{coskd}}_2-P_4}{{\mathrm{sinkd}}_2}\\ v_d=\frac{i}{\mathrm{\ρ}c}{P}_3{\mathrm{sinkh}}_2-{\mathrm{coskh}}_2\frac{P_3{\mathrm{coskd}}_2-P_4}{{\mathrm{sinkd}}_2}\end{array}---\left(6\right)$

In above formula, p _urepresent the acoustic pressure of acoustic stimulation sample first surface, v _urepresent the vibration velocity of acoustic stimulation sample first surface, p _drepresent the acoustic pressure of acoustic stimulation sample second surface, v _drepresent the vibration velocity of acoustic stimulation sample second surface, d ₁represent the first nautical receiving set and the second nautical receiving set spacing, h ₁represent the first nautical receiving set and acoustic stimulation sample first surface spacing, d ₂represent the 3rd nautical receiving set and the 4th nautical receiving set spacing, h ₂represent the 3rd nautical receiving set and acoustic stimulation sample second surface spacing;

Step 5, on the basis of the pressure and particle velocity on first, second surface of acoustic stimulation sample, using acoustic stimulation transport function as unknown quantity, obtains two equations about transport function:

$\left[\begin{array}{cccc}{p}_u& v_u& & \\ & & p_u& v_u\end{array}\right]\·\left\{\begin{array}{c}{H}_{11}\\ H_{12}\\ H_{21}\\ H_{22}\end{array}\right\}=\left\{\begin{array}{c}{p}_d\\ v_d\end{array}\right\}---\left(7\right)$

Step 6, adds water in the first surface side of acoustic stimulation sample, changes the liquid column length of acoustic stimulation sample first surface side; Then repeat step one to step 5, obtain another two equations about transport function:

$\left[\begin{array}{cccc}{p^{\′}}_u& {v^{\′}}_u& & \\ & & {p^{\′}}_u& {v^{\′}}_u\end{array}\right]\·\left\{\begin{array}{c}{H}_{11}\\ H_{12}\\ H_{21}\\ H_{22}\end{array}\right\}=\left\{\begin{array}{c}{p^{\′}}_d\\ {v^{\′}}_d\end{array}\right\}---\left(8\right)$

Step 7, the system of equations of simultaneous step 5 and step 6, obtains the system of equations about transport function that can solve:

$\left[\begin{array}{cccc}{p}_u& v_u& & \\ & & p_u& v_u\\ {p^{\′}}_u& {v^{\′}}_u& & \\ & & {p^{\′}}_u& {v^{\′}}_u\end{array}\right]\·\left\{\begin{array}{c}{H}_{11}\\ H_{12}\\ H_{21}\\ H_{22}\end{array}\right\}=\left\{\begin{array}{c}{p}_d\\ v_d\\ {p^{\′}}_d\\ {v^{\′}}_d\end{array}\right\}---\left(9\right)$

Solve this system of equations, obtain the transport function of acoustic stimulation;

Step 8, calculates the input acoustic impedance of acoustic stimulation sample according to transport function and transmits acoustic impedance:

Z ₁₁＝H ₁₁/H ₂₁

Z ₁₂＝(H ₁₂·H ₂₁-H ₁₁·H ₂₂)/H ₂₁

(10)

Z ₂₁＝1/H ₂₁

Z ₂₂＝-H ₂₂/H ₂₁

In above formula, Z ₁₁represent the input acoustic impedance of acoustic stimulation sample first surface, Z ₁₂represent the transmission acoustic impedance of acoustic stimulation sample first surface to second surface, Z ₂₁represent the transmission acoustic impedance of acoustic stimulation sample second surface to first surface, Z ₂₂represent the input acoustic impedance of acoustic stimulation sample second surface.

Advantageous Effects of the present invention is:

The present invention can overcome two shortcomings of existing method of testing: one, existing method test result depend on backing, and this method of testing then can not rely on backing thus ensures the precision of medium and low frequency test; Two, existing method Impedance measurement need test twice, and this method of testing does not need to take out sample and again pastes backing, therefore easy measuring process, thus promotes and measure efficiency.

Accompanying drawing explanation

Fig. 1 is acoustic stimulation input acoustic impedance and the proving installation structural representation transmitting acoustic impedance.

Fig. 2 is input sound impedance test value and the theoretical value correlation curve of typical uniformity rubber layer sample.

Fig. 3 is transmission sound impedance test value and the theoretical value correlation curve of typical uniformity rubber layer sample.

Fig. 1 description of symbols: liquid level on 1-underwater sound plane sound wave conduit; 2-1# nautical receiving set; 3-2# nautical receiving set; 4-acoustic stimulation sample; 5-3# nautical receiving set; 6-4# nautical receiving set; 7-transmitting transducer; D1-1# nautical receiving set and 2# nautical receiving set spacing; H1-1# nautical receiving set and acoustic stimulation sample upper surface spacing; D2-3# nautical receiving set and 4# nautical receiving set spacing; H2-3# nautical receiving set and acoustic stimulation sample lower surface spacing.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described further.

The present invention mainly comprises the following steps:

Step one, with typical uniformity rubber layer sample for acoustic stimulation sample, as shown in Figure 1, acoustic stimulation sample 4 is placed in underwater sound plane sound wave conduit middle tube body centre position, in the present embodiment, body is vertically placed (also can be horizontal), ensure that acoustic stimulation sample 4 upper surface and upper surface have certain liquid-column height (being more than 1m in the present embodiment).In the body chamber of underwater sound plane sound wave conduit, one end (being lower end in the present embodiment) is provided with transmitting transducer 7, two nautical receiving sets are provided with: 3# nautical receiving set 5,4# nautical receiving set 6 between transmitting transducer 7 and acoustic stimulation sample 4, acoustic stimulation sample 4 underwater sound plane sound wave conduit is provided with two nautical receiving sets between liquid level 1: 1# nautical receiving set 2,2# nautical receiving set 3, four nautical receiving sets are connected with data collecting instrument (not shown in figure 1) respectively, and data collecting instrument is connected with Survey control computer (not shown in figure 1).

Preferably, nautical receiving set adopts 8103 nautical receiving sets of B & K company, data collecting instrument adopts B & K company 3560D type Acquisition Instrument, signal transmitting, sound and vibration signal synchronous collection can be realized, Survey control computer is provided with PulseLabshop software, can carry out signal transmitting, data acquisition and calculate the input acoustic impedance of acoustic stimulation sample 4 and transmit acoustic impedance by control data Acquisition Instrument.

Step 2, drives transmitting transducer 7 to launch and stablize wideband white noise signal, effective and carry out data acquisition by data collecting instrument confirmation signal.

Step 3, data collecting instrument gathers the acoustic pressure P of 1# ~ 4# nautical receiving set simultaneously ₁~ P ₄, save as data file.

Step 4, reads acoustic pressure data document, and calculates the pressure and particle velocity of acoustic stimulation sample 4 upper and lower surface according to the following formula:

$\begin{array}{c}{p}_u=P_1{\mathrm{coskh}}_1-{\mathrm{sinkh}}_1\frac{P_1{\mathrm{coskd}}_1-P_2}{{\mathrm{sinkd}}_1}\\ v_u=-i\frac{{\mathrm{sinkh}}_1}{\mathrm{\ρ}c}{P}_1-{\mathrm{icoskh}}_1\frac{P_1{\mathrm{coskd}}_1-P_2}{{\mathrm{\ρcsinkd}}_1}\\ p_d=P_3{\mathrm{coskh}}_2+{\mathrm{sinkh}}_2\frac{P_3{\mathrm{coskd}}_2-P_4}{{\mathrm{sinkd}}_2}\\ v_d=\frac{i}{\mathrm{\ρ}c}{P}_3{\mathrm{sinkh}}_2-{\mathrm{coskh}}_2\frac{P_3{\mathrm{coskd}}_2-P_4}{{\mathrm{sinkd}}_2}\end{array}---\left(11\right)$

In formula (1), p _urepresent the acoustic pressure of acoustic stimulation sample upper surface, v _urepresent the vibration velocity of acoustic stimulation sample upper surface, p _drepresent the acoustic pressure of acoustic stimulation sample lower surface, v _drepresent the vibration velocity of acoustic stimulation sample lower surface, d ₁represent 1# nautical receiving set and 2# nautical receiving set spacing, h ₁represent 1# nautical receiving set and acoustic stimulation sample upper surface spacing, d ₂represent 3# nautical receiving set and 4# nautical receiving set spacing, h ₂represent 3# nautical receiving set and acoustic stimulation sample lower surface spacing.

Step 5, on the basis of the pressure and particle velocity of acoustic stimulation sample 4 upper and lower surface, using acoustic stimulation transport function as unknown quantity, can about two of a transport function equation:

$\left[\begin{array}{cccc}{p}_u& v_u& & \\ & & p_u& v_u\end{array}\right]\·\left\{\begin{array}{c}{H}_{11}\\ H_{12}\\ H_{21}\\ H_{22}\end{array}\right\}=\left\{\begin{array}{c}{p}_d\\ v_d\end{array}\right\}---\left(12\right)$

Step 6, adds water on acoustic stimulation sample 4 top, changes acoustic stimulation sample 4 top liquid column length.Then repeat step one to step 5, remeasure storage acoustic pressure data, and calculate according to respective formula, obtain another two equations about transport function:

$\left[\begin{array}{cccc}{p^{\′}}_u& {v^{\′}}_u& & \\ & & {p^{\′}}_u& {v^{\′}}_u\end{array}\right]\·\left\{\begin{array}{c}{H}_{11}\\ H_{12}\\ H_{21}\\ H_{22}\end{array}\right\}=\left\{\begin{array}{c}{p^{\′}}_d\\ {v^{\′}}_d\end{array}\right\}---\left(13\right)$

Step 7, the system of equations of simultaneous step 5 and step 6, obtains the system of equations about transport function that can solve:

$\left[\begin{array}{cccc}{p}_u& v_u& & \\ & & p_u& v_u\\ {p^{\′}}_u& {v^{\′}}_u& & \\ & & {p^{\′}}_u& {v^{\′}}_u\end{array}\right]\·\left\{\begin{array}{c}{H}_{11}\\ H_{12}\\ H_{21}\\ H_{22}\end{array}\right\}=\left\{\begin{array}{c}{p}_d\\ v_d\\ {p^{\′}}_d\\ {v^{\′}}_d\end{array}\right\}---\left(14\right)$

Solve this system of equations, obtain the transport function of acoustic stimulation.

Step 8, calculates the input acoustic impedance of acoustic stimulation sample according to transport function and transmits acoustic impedance:

Z ₁₁＝H ₁₁/H ₂₁

Z ₁₂＝(H ₁₂·H ₂₁-H ₁₁·H ₂₂)/H ₂₁

(15)

Z ₂₁＝1/H ₂₁

Z ₂₂＝-H ₂₂/H ₂₁

In formula (5), Z ₁₁represent the input acoustic impedance of acoustic stimulation sample upper surface, Z ₁₂represent the transmission acoustic impedance of acoustic stimulation sample upper surface to lower surface, Z ₂₁represent the transmission acoustic impedance of acoustic stimulation sample lower surface to upper surface, Z ₂₂represent the input acoustic impedance of acoustic stimulation sample lower surface.

Finally, carry out data processing, obtain the input acoustic impedance of typical uniformity rubber sample and transmit acoustic impedance with frequency variation curve, and contrasting with theoretical value, as shown in Figures 2 and 3.Above-mentioned curve shows, test result and notional result are coincide better.

Above-described is only the preferred embodiment of the present invention, the invention is not restricted to above embodiment.Be appreciated that the oher improvements and changes that those skilled in the art directly derive without departing from the basic idea of the present invention or associate, all should think and be included within protection scope of the present invention.

Claims (1)

1. do not rely on an acoustic stimulation sound impedance test method for backing, it is characterized in that comprising the steps:

Step one, acoustic stimulation sample is placed in the body centre position of underwater sound plane sound wave conduit, ensure that two face side of acoustic stimulation sample have fluid column, in the body chamber of described underwater sound plane sound wave conduit, one end is provided with transmitting transducer, the first nautical receiving set and the second nautical receiving set is provided with in the fluid column of described acoustic stimulation sample first surface side, the 3rd nautical receiving set and the 4th nautical receiving set is provided with in fluid column between acoustic stimulation sample second surface side and transmitting transducer, wherein the first nautical receiving set and acoustic stimulation sample first surface spacing are greater than the second nautical receiving set and acoustic stimulation sample first surface spacing, 4th nautical receiving set and acoustic stimulation sample second surface spacing are greater than the 4th nautical receiving set and acoustic stimulation sample second surface spacing, described each nautical receiving set is connected with data collecting instrument respectively, described data collecting instrument is connected with Survey control computer,

Step 2, drives described transmitting transducer to launch and stablizes wideband white noise signal;

Step 3, described data collecting instrument gathers the acoustic pressure P of first to fourth nautical receiving set simultaneously ₁~ P ₄, save as data file;

Step 4, reads acoustic pressure data document, and calculates the pressure and particle velocity on acoustic stimulation sample first and second surface according to the following formula:

$p_u=P_1{\mathrm{coskh}}_1-{\mathrm{sinkh}}_1\frac{P_1{\mathrm{coskd}}_1-P_2}{{\mathrm{sinkd}}_1}$

$v_u=-i\frac{{\mathrm{sinkh}}_1}{\mathrm{\ρ}c}{P}_1-{\mathrm{icoskh}}_1\frac{P_1{\mathrm{coskd}}_1-P_2}{{\mathrm{\ρcsinkd}}_1}$

(1)

$p_d=P_3{\mathrm{coskh}}_2+{\mathrm{sinkh}}_2\frac{P_3{\mathrm{coskd}}_2-P_4}{{\mathrm{sinkd}}_2}$

$v_d=\frac{i}{\mathrm{\ρ}c}{P}_3{\mathrm{sinkh}}_2-{\mathrm{coskh}}_2\frac{P_3{\mathrm{coskd}}_2-P_4}{{\mathrm{sinkd}}_2}$

In above formula, p _urepresent the acoustic pressure of acoustic stimulation sample first surface, v _urepresent the vibration velocity of acoustic stimulation sample first surface, p _drepresent the acoustic pressure of acoustic stimulation sample second surface, v _drepresent the vibration velocity of acoustic stimulation sample second surface, d ₁represent the first nautical receiving set and the second nautical receiving set spacing, h ₁represent the first nautical receiving set and acoustic stimulation sample first surface spacing, d ₂represent the 3rd nautical receiving set and the 4th nautical receiving set spacing, h ₂represent the 3rd nautical receiving set and acoustic stimulation sample second surface spacing;

Step 5, on the basis of the pressure and particle velocity on first, second surface of acoustic stimulation sample, using acoustic stimulation transport function as unknown quantity, obtains two equations about transport function:

$\left[\begin{array}{cccc}{p}_u& v_u& & \\ & & p_u& v_u\end{array}\right]\·\left\{\begin{array}{c}{H}_{11}\\ H_{12}\\ H_{21}\\ H_{22}\end{array}\right\}=\left\{\begin{array}{c}{p}_d\\ v_d\end{array}\right\}---\left(2\right)$

Step 6, adds water in the first surface side of acoustic stimulation sample, changes the liquid column length of acoustic stimulation sample first surface side; Then repeat step one to step 5, obtain another two equations about transport function:

$\left[\begin{array}{cccc}{p^{\′}}_u& {v^{\′}}_u& & \\ & & {p^{\′}}_u& {v^{\′}}_u\end{array}\right]\·\left\{\begin{array}{c}{H}_{11}\\ H_{12}\\ H_{21}\\ H_{22}\end{array}\right\}=\left\{\begin{array}{c}{p^{\′}}_d\\ {v^{\′}}_d\end{array}\right\}---\left(3\right)$

Step 7, the system of equations of simultaneous step 5 and step 6, obtains the system of equations about transport function that can solve:

$\left[\begin{array}{cccc}{p}_u& v_u& & \\ & & p_u& v_u\\ {p^{\′}}_u& {v^{\′}}_u& & \\ & & {p^{\′}}_u& {v^{\′}}_u\end{array}\right]\·\left\{\begin{array}{c}{H}_{11}\\ H_{12}\\ H_{21}\\ H_{22}\end{array}\right\}=\left\{\begin{array}{c}{p}_d\\ v_d\\ {p^{\′}}_d\\ {v^{\′}}_d\end{array}\right\}---\left(4\right)$

Solve this system of equations, obtain the transport function of acoustic stimulation;

Step 8, calculates the input acoustic impedance of acoustic stimulation sample according to transport function and transmits acoustic impedance:

Z ₁₁＝H ₁₁/H ₂₁

Z ₁₂＝(H ₁₂·H ₂₁-H ₁₁·H ₂₂)/H ₂₁(5)

Z ₂₁＝1/H ₂₁

Z ₂₂＝-H ₂₂/H ₂₁

In above formula, Z ₁₁represent the input acoustic impedance of acoustic stimulation sample first surface, Z ₁₂represent the transmission acoustic impedance of acoustic stimulation sample first surface to second surface, Z ₂₁represent the transmission acoustic impedance of acoustic stimulation sample second surface to first surface, Z ₂₂represent the input acoustic impedance of acoustic stimulation sample second surface.