Rapid prediction method for noise of closed space structure

Abstract

The invention discloses a rapid prediction method for noise of a closed space structure. The method comprises the following steps: S1, dispersing each surface of the closed space structure into n equivalent sound source areas; s2, calculating the distance between the central point of the ith equivalent sound source area and the to-be-predicted point; s3, calculating the sound radiation efficiency of the ith equivalent sound source area; s4, calculating the equivalent sound source sound pressure of the equivalent sound source area i; and S5, according to an energy superposition principle, synthesizing the sound pressure of each equivalent sound source into a total sound pressure level. According to the method, the equivalent sound source region is directly divided, a tedious grid matching and mapping process is abandoned, and the efficiency is improved by 98% compared with that of a traditional method; the method can reflect the influence of different surface vibrations on noise, the calculation precision is remarkably improved, and the method can be widely applied to the fields of building design, environmental influence evaluation, noise treatment engineering and the like.

Description

Technical Field

[0001] This invention relates to the field of building structure vibration and noise control, and in particular to a rapid prediction method for noise in enclosed space structures. Background Technology

[0002] Structural noise is low-frequency sound waves (dominant frequency below 63Hz) generated by mechanical vibrations transmitted and radiated through building components (such as floor slabs and walls). Its wavelength can reach 5.4m, penetrating conventional sound insulation structures and forming standing wave resonances in enclosed spaces. Actual measurement data shows that floor structural noise caused by subway operation can reach 45-68 dB(A) at night, far exceeding the nighttime limit of 40 dB(A) for residential areas stipulated in the "Environmental Noise Quality Standard" (GB 3096-2008). Long-term exposure to this type of noise can lead to insomnia, anxiety, and decreased work efficiency. Statistics from a certain city's rail transit complaint system show that 72% of noise complaints are directly related to low-frequency structural noise.

[0003] Current mainstream finite element method (FEM) and boundary element method (BEM) require the establishment of a global vibration-acoustic coupled model, transferring data through mesh mapping. Taking a high-speed railway station as an example, it requires dividing into more than 5 million mesh elements, with a single full-frequency calculation taking 12 days (72-core server). Irregular structures (curved surfaces, irregular nodes) require repeated mesh adjustments, extending the preprocessing cycle by more than 40%. Although these methods have high theoretical accuracy, their modeling complexity and massive computational resource consumption severely restrict engineering applications. Most projects are forced to simplify the model due to the time consumption, resulting in inaccurate noise distribution predictions.

[0004] To address this, engineers have resorted to empirical formulas (such as the formulas recommended in the industry standard "HJ 453-2021 Technical Guidelines for Environmental Impact Assessment in Urban Rail Transit"), which rely solely on a single vibration velocity level to estimate sound pressure level. This approach neglects the influence of vibration acceleration distribution and changes in sound radiation efficiency, resulting in significant prediction errors for complex boundaries. This method fails to meet the stringent requirements for indoor acoustic environments stipulated in the "Green Building Evaluation Standard" (GB / T 50378-2019). Therefore, a rapid calculation method that balances efficiency and accuracy is urgently needed, compatible with existing test or simulation vibration data, enabling rapid response and controllable calculation precision. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for rapid prediction of noise in enclosed spatial structures with controllable accuracy.

[0006] Therefore, the present invention adopts the following technical solution:

[0007] A rapid method for predicting noise in enclosed space structures includes the following steps:

[0008] S1, discretizes each surface of the closed spatial structure as... Let there be an equivalent sound source region, and let the first... The coordinates of the center point of each equivalent sound source region are: The area is , =1~ ;

[0009] S2, calculate the first The center point and the point to be predicted of each equivalent sound source region distance :

[0010] S3, Calculate the first Sound radiation efficiency of an equivalent sound source region :

[0011] ,

[0012] In the formula, The critical frequency of a closed spatial structure; The center frequency of 1 / 3 octave band for the enclosed space structure or the frequency specified by the user;

[0013] S4, Calculate the equivalent sound source region equivalent sound source sound pressure :

[0014] ,

[0015] In the formula, air density; The speed of sound in air; Equivalent sound source region Vibration velocity at the center point The effective acceleration values ​​are exported from the structural finite element method software. The reverberation time of an enclosed space; For reference only; This is a directional correction factor;

[0016] S5, based on the principle of energy superposition, combines the sound pressure levels of each equivalent sound source. The overall sound pressure level is:

[0017]

[0018] in, For reference sound pressure level, .

[0019] In step S3 above, the critical frequency The calculation formula is:

[0020] ,

[0021] in, The speed of sound in air; The thickness of each surface of the enclosed space structure; Let be the longitudinal wave velocity of the vibration propagation, where The elastic modulus of a closed spatial structure. For the density of a closed space structure, Poisson's ratio for a closed spatial structure.

[0022] Preferably, for large building interior structures, f ≤ 200Hz.

[0023] In step S4 above, the reference value The calculation formula is:

[0024] ,

[0025] in, The volume of the enclosed space; The surface area that encloses the enclosed space.

[0026] In step S4 above, the directionality correction coefficient The calculation formula is:

[0027] ,

[0028] in, Equivalent sound source region The number of walls that the boundary contacts, and its value is an integer ranging from 0 to 3.

[0029] In step S4, the reverberation time T of the enclosed space can be obtained by querying the space according to its purpose or by calculating it according to the Sabine formula.

[0030] In step S4 above, the structural finite element software is Midas or Ansys.

[0031] The prediction method of this invention is applicable to the structural noise assessment of rooms inside large buildings such as stations, hospitals, and office buildings, and is especially applicable to noise control projects of buildings along rail transit lines, buildings above depots, and industrial plants.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. This invention directly divides the equivalent sound source region, eliminating the cumbersome mesh matching and mapping process. It only requires inputting wall geometry parameters and vibration acceleration data to complete the prediction of the sound pressure level of the entire room in a short time. Compared with traditional methods, it improves efficiency by 98%, significantly shortens the design cycle, and significantly improves computational and design efficiency.

[0034] 2. By introducing an equivalent sound source region and a directivity correction coefficient, this invention accurately quantifies the sound radiation characteristics of complex surfaces, reflecting the impact of different surface vibrations on noise. The calculation accuracy is significantly improved compared to traditional empirical formulas (such as HJ 453-2021), providing technical support for structural noise prediction and control.

[0035] 3. This invention introduces the product of vibration velocity and the square root of area, ensuring that the total energy remains approximately constant under any discretization method. This avoids the shortcomings of traditional methods, such as coarse mesh overestimating local sound pressure, fine mesh underestimating energy concentration effect, and sound energy being affected by mesh density. This feature greatly reduces the dependence on engineers' meshing experience, enabling junior technicians to quickly obtain reliable results.

[0036] 4. This invention simplifies structural noise prediction through global modeling and energy correction, transforming it from a "high-threshold task" for professional acoustic teams into a "routine operation" for ordinary engineers while ensuring accuracy. It can be widely applied in fields such as architectural design, environmental impact assessment, and noise control engineering, and has significant industrialization and promotion value. Attached Figure Description

[0037] Figure 1 This is a flowchart of the method for rapid prediction of noise in enclosed space structures according to the present invention. Detailed Implementation

[0038] The method of the present invention will be described in detail below with reference to the accompanying drawings.

[0039] See Figure 1 The method for rapid prediction of noise in enclosed space structures according to the present invention includes the following steps:

[0040] S1, discretizes each surface of the closed spatial structure as... Let there be an equivalent sound source region, and let the first... The coordinates of the center point of each equivalent sound source region are: The area is , =1~ ;

[0041] S2, calculate the first The distance between the center point of each equivalent sound source region and the point to be predicted :

[0042] ,

[0043] in, The coordinates of the point to be predicted;

[0044] S3, Calculate the first Sound radiation efficiency of an equivalent sound source region :

[0045] ,

[0046] In the formula, The critical frequency of a closed spatial structure; The center frequency of 1 / 3 octave band for an enclosed space structure or a user-specified frequency (in the interior structure of large buildings). (below 200Hz)

[0047] in, The calculation formula is as follows:

[0048] ,

[0049] in, The speed of sound in air; The longitudinal wave velocity of the vibration propagation. The elastic modulus of a closed spatial structure; Density of enclosed spatial structures; Poisson's ratio for a closed spatial structure; This refers to the thickness of each surface of the enclosed spatial structure.

[0050] S4, Calculate the equivalent sound source region equivalent sound source sound pressure :

[0051] ,

[0052] In the formula, air density; The speed of sound in air; Equivalent sound source region Vibration velocity at the center point Effective acceleration values ​​exported from structural finite element software (Midas, Ansys); The reverberation time of an enclosed space; For reference only; This is the directivity correction coefficient; the reverberation time T of the enclosed space can be obtained by querying the space's purpose or by calculating it according to the Sabine formula.

[0053] The reference value The calculation formula is as follows:

[0054] ,

[0055] in, The volume of the enclosed space; The surface area that encloses the enclosed space.

[0056] The directional correction coefficient The calculation formula is as follows:

[0057] ,

[0058] in, Equivalent sound source region The number of wall surfaces that the boundary contacts, and its value is an integer ranging from 0 to 3.

[0059] S5, based on the principle of energy superposition, combines the sound pressure levels of each equivalent sound source. The overall sound pressure level is:

[0060]

[0061] in, For reference sound pressure level, .

Claims

1. A rapid prediction method for noise in enclosed space structures, characterized in that, Includes the following steps: S1, discretizes each surface of the closed spatial structure as... Let there be an equivalent sound source region, and let the first... The coordinates of the center point of each equivalent sound source region are: The area is , =1~ ; S2, calculate the first The center point and the point to be predicted of each equivalent sound source region distance : S3, Calculate the first Sound radiation efficiency of an equivalent sound source region : ， In the formula, The critical frequency for a closed spatial structure; The center frequency of 1 / 3 octave band for the enclosed space structure or the frequency specified by the user; S4, Calculate the equivalent sound source region equivalent sound source sound pressure : ， In the formula, air density; The speed of sound in air; Equivalent sound source region Vibration velocity at the center point The effective acceleration values ​​are exported from the structural finite element method software. The reverberation time of an enclosed space; For reference only; This is a directional correction factor; S5, based on the principle of energy superposition, combines the sound pressure levels of each equivalent sound source. The overall sound pressure level is: in, For reference sound pressure level, .

2. The rapid prediction method according to claim 1, characterized in that, The critical frequency mentioned in S3 The calculation formula is: ， in, The speed of sound in air; The thickness of each surface of the enclosed space structure; Let be the longitudinal wave velocity of the vibration propagation, where The elastic modulus of a closed spatial structure. For the density of a closed space structure, Poisson's ratio for a closed spatial structure.

3. The rapid prediction method according to claim 1, characterized in that, In S3, for large building interior structures, f≤200Hz.

4. The rapid prediction method according to claim 1, characterized in that, In S4, the reference value The calculation formula is: ， in, The volume of the enclosed space; The surface area that encloses the enclosed space.

5. The rapid prediction method according to claim 1, characterized in that, In S4, the directional correction coefficient The calculation formula is: ， in, Equivalent sound source region The number of walls that the boundary contacts, and its value is an integer ranging from 0 to 3.

6. The rapid prediction method according to claim 1, characterized in that, In S4, the reverberation time T of the enclosed space can be obtained by querying the space according to its purpose, or calculated according to the Sabine formula.

7. The rapid prediction method according to claim 1, characterized in that, In S4, the structural finite element software is Midas or Ansys.

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