CN-122016026-A - Sound velocity calculation method and system based on pulse tube experiment

CN122016026ACN 122016026 ACN122016026 ACN 122016026ACN-122016026-A

Abstract

The invention provides a sound velocity calculation method and a sound velocity calculation system based on a pulse tube experiment, which relate to the technical field of sound velocity measurement, wherein the method comprises the steps of obtaining a first complex reflection coefficient of a tested sample under an air backing and a second complex reflection coefficient under a rigid backing by using the pulse tube experiment; based on the first complex reflection coefficient and the second complex reflection coefficient, the real part and the imaginary part of a calculation result are obtained in a combined mode, the density of water, the sound velocity in water, the frequency, the density of a tested sample and the thickness of the tested sample are obtained through calculation, a constant term is obtained through calculation, and the sound velocity and the attenuation coefficient of the tested sample are obtained through calculation according to the thickness of the tested sample, the real part, the imaginary part, the constant term and the frequency. The invention solves the technical problems of unstable numerical value, low calculation efficiency and inaccurate result caused by difficult solving of an overrun equation in sound velocity calculation by the traditional pulse tube experimental method.

Inventors

ZHOU XIAOQIANG
ZHANG LEI
HUANG QINGYANG
HE WENKAI
ZHOU HONGHAO
LU YUAN
FANG JIAHAO
CHEN ZEYANG

Assignees

华中科技大学

Dates

Publication Date: 20260512
Application Date: 20260109

Claims (10)

1. A method for calculating sound velocity based on pulse tube experiments, the method comprising: obtaining a first complex reflection coefficient of a tested sample under an air backing and a second complex reflection coefficient under a rigid backing respectively by utilizing a pulse tube experiment; based on the first complex reflection coefficient and the second complex reflection coefficient, jointly obtaining a real part and an imaginary part of a calculation result; acquiring the density of water, the sound velocity, the frequency in the water, the density of a tested sample and the thickness of the tested sample, and calculating to obtain a constant term; and calculating the sound velocity and attenuation coefficient of the tested sample according to the thickness, the real part, the imaginary part, the constant term and the frequency of the tested sample.
2. The method of claim 1, wherein the real part is a real part of a pulse tube based sound velocity calculation method And imaginary part The method comprises the following steps of: ; Wherein, the A modulus value representing the first complex reflection coefficient; a modulus value representing a second complex reflection coefficient; A phase angle representing the first complex reflection coefficient; representing the phase angle of the second complex reflection coefficient.
3. The method of claim 1, wherein the constant term is a constant term The calculation formula of (2) is as follows: ; Wherein, the Represents the density of water; representing the speed of sound in water; Representing the frequency; Representing the density of the sample to be tested; Indicating the thickness of the test specimen.
4. The method for calculating sound velocity based on pulse tube experiments according to any one of claims 1 to 3, wherein the sound velocity of the test sample The calculation formula is as follows: And (2) and ; Wherein, the Representing the attenuation coefficient of the tested sample; Representing the frequency; Representing the thickness of the tested sample; representing the constant term; representing the real part; Representing the imaginary part.
5. The method of claim 4, wherein the attenuation coefficient of the sample is determined by a pulse tube test The calculation formula of (2) is as follows: And (2) and 。
6. The method for calculating sound velocity based on pulse tube experiments according to any one of claims 1 to 3, wherein real part and imaginary part of calculation results are obtained jointly based on the first complex reflection coefficient and the second complex reflection coefficient, specifically comprising: Respectively obtaining a first relation between the sound velocity and attenuation coefficient of the sample to be tested under the air backing and the modulus value and phase angle of the first complex reflection coefficient, and a second relation between the sound velocity and attenuation coefficient of the sample to be tested under the rigid backing and the modulus value and phase angle of the second complex reflection coefficient; Order the And due to Multiplying the deformed first relation and the second relation to obtain a first formula: ; Applying the first formula to And Respectively split to obtain the product under the air backing First simplified sum of (2) under a rigid backing Is a second reduction of (2); The real part and the imaginary part of the first formula are obtained by the first simplified formula and the second simplified formula.
7. A base according to claim 6a sound velocity calculating method for pulse tube experiments, the method is characterized in that the first simplified formula is as follows: ; The second reduction is: 。
8. The method for calculating sound velocity based on pulse tube experiments according to claim 6, wherein the calculating method of sound velocity of the sample to be tested specifically comprises: Rewriting the first formula to a second formula based on the real part, the imaginary part, and the constant term: ; Will be Substituting the second formula to obtain a third formula; And disassembling both sides of the equation of the third formula into a real part and an imaginary part, wherein the real part and the imaginary part of the equation are respectively equal, and obtaining the sound velocity and the attenuation coefficient of the tested sample by resolving.
9. The method of claim 1, wherein the first complex reflection coefficient and the second complex reflection coefficient are obtained by any one of experimental measurement, finite element simulation, and theoretical calculation.
10. A sound speed computing system based on pulse tube experiments comprising a memory, a processor and a computer program stored on the memory, wherein the processor executes the computer program to implement the steps of the method of any one of claims 1-9.

Description

Sound velocity calculation method and system based on pulse tube experiment Technical Field The invention relates to the technical field of sound velocity measurement, in particular to a sound velocity calculation method and system based on a pulse tube experiment, which can be used for measuring sound velocity of any structure. Background Accurate measurement of structural sound velocity is a key basis for achieving acoustic super-surface design and acoustic impedance matching. Currently, the main methods for measuring the speed of sound of a structure include pulse tube experiments and transients. The sound velocity measuring method based on the pulse tube experiment mainly comprises the steps of respectively measuring reflection coefficients of a sample under the conditions of an air backing (acoustic soft end) and a rigid backing (acoustic hard end), establishing a relation between input acoustic impedance and the reflection coefficients, and further solving sound velocity and attenuation coefficients. However, the equation involved in this method is an overrun equation, and includes two unknown variables, namely the speed of sound and the attenuation coefficient. In the process of solving the numerical values, because of the nonlinear characteristic of the equation, the numerical value iterative algorithm such as gradient descent is often needed, and the numerical value iterative algorithm is easy to fall into a local optimal solution, so that the calculation result is inaccurate and the stability is poor. In addition, the experimental measurement error can further aggravate the inconsistency of the solving result under two backing conditions, and the self-consistency of the sound velocity and the attenuation coefficient is difficult to ensure. In addition, although the transient method can directly calculate the sound velocity through the time difference, the transient method needs to be provided with a transmitting device and a receiving device, and the system is complex and the difficulty of low-frequency measurement is high. Therefore, the existing methods have obvious limitations in terms of numerical stability, accuracy, efficiency and applicability. Disclosure of Invention Aiming at the problems, the invention provides a sound velocity calculating method and a sound velocity calculating system based on a pulse tube experiment, which aim to solve the technical problems of unstable numerical value, low calculating efficiency and inaccurate result caused by difficult solving of an overrun equation in sound velocity calculation of the conventional pulse tube experiment method. In a first aspect, the present invention provides a method for calculating sound velocity based on pulse tube experiments, the method comprising: obtaining a first complex reflection coefficient of a tested sample under an air backing and a second complex reflection coefficient under a rigid backing respectively by utilizing a pulse tube experiment; based on the first complex reflection coefficient and the second complex reflection coefficient, jointly obtaining a real part and an imaginary part of a calculation result; acquiring the density of water, the sound velocity, the frequency in the water, the density of a tested sample and the thickness of the tested sample, and calculating to obtain a constant term; and calculating the sound velocity and attenuation coefficient of the tested sample according to the thickness, the real part, the imaginary part, the constant term and the frequency of the tested sample. Further, the real partAnd imaginary partThe method comprises the following steps of: ; Wherein, the A modulus value representing the first complex reflection coefficient; a modulus value representing a second complex reflection coefficient; A phase angle representing the first complex reflection coefficient; representing the phase angle of the second complex reflection coefficient. Further, the constant termThe calculation formula of (2) is as follows: ; Wherein, the Represents the density of water; representing the speed of sound in water; Representing the frequency; Representing the density of the sample to be tested; Indicating the thickness of the test specimen. Further, the sound velocity of the test sampleThe calculation formula is as follows: And (2) and ; Wherein, the Representing the attenuation coefficient of the tested sample; Representing the frequency; Representing the thickness of the tested sample; representing the constant term; representing the real part; Representing the imaginary part. Further, the attenuation coefficient of the test sampleThe calculation formula of (2) is as follows: And (2) and 。 Further, based on the first complex reflection coefficient and the second complex reflection coefficient, real parts and imaginary parts of calculation results are obtained in a combined mode, and the method specifically comprises the following steps: Respectively obtaining a first relation betwe