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FE/WSM method for structural acoustic vibration calculation under Pekeris waveguide

A technology of waveguide and elastic structure, which is applied in the fields of underwater target detection and recognition, acoustic measurement, and acoustic radiation prediction of elastic structures.

Active Publication Date: 2021-01-22
TIANJIN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the coupling effect between structure and fluid, structure and environment is directly ignored in the near field, and it is impossible to accurately conduct research on the fields related to the near-field sound field of elastic structures (sound field measurement, vibration and noise reduction, and near-field sound radiation characteristics, etc.).
All of the above have led to the inability to effectively carry out research on acoustic radiation from elastic structures under waveguides from the perspective of theoretical solutions and numerical methods. However, it is of great significance to the acoustic radiation, prediction and identification of underwater structures in the ocean. Research approach to address structure-acoustic radiation in oceanic ducts

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  • FE/WSM method for structural acoustic vibration calculation under Pekeris waveguide
  • FE/WSM method for structural acoustic vibration calculation under Pekeris waveguide
  • FE/WSM method for structural acoustic vibration calculation under Pekeris waveguide

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Embodiment 1

[0047] see Figure 1 to Figure 5 , the embodiment of the present invention provides a FE / WSM-based Pekeris waveguide elastic structure vibration calculation method, the method includes the following steps:

[0048] Step 1: Use the finite element method to establish a multi-physics field coupling model of elastic structure-acoustic radiation under the local Pekeris waveguide, and perform discrete processing of the elastic structure under the three-dimensional Pekeris waveguide; use the finite difference method to solve each coupling model simultaneously, and extract the structure under the local Pekeris waveguide surface vibration data matrix U;

[0049] Among them, on the coupling surface where the surface of the elastic structure is in contact with the external fluid, the vibration velocity in the normal direction of the structure surface is the same as the vibration velocity of the external fluid medium, and the interaction relationship between the structural vibration equat...

Embodiment 2

[0057] The scheme in embodiment 1 is further introduced below in conjunction with specific examples, see the following description for details:

[0058] Such as figure 1 As shown, it is a schematic diagram of the FE / WSM theoretical model of the low-frequency acoustic radiation of any elastic structure under the Pekeris waveguide of the embodiment of the present invention. The theoretical model consists of the near-field finite element method for the discrete structure and the far-field wave superposition for the calculation of the sound field. Its calculation steps mainly include:

[0059] 1. Wave superposition method under Pekeris waveguide

[0060] Such as figure 1 As shown, the fluid density is ρ a , the fluid sound velocity is c a . The surface of the elastic structure is denoted as S, and n is the normal vector outside the surface of the structure. P is the sound pressure of the mid-point of the external fluid. Ω is the equivalent source surface inside the structu...

Embodiment 3

[0154] Calculation example 1: Calculation of point source sound propagation under Pekeris shallow sea waveguide

[0155] In order to verify the accuracy of solving Green's function by mirror method and normal wave method, Figure 5 As shown, it is a schematic diagram of the established point source sound propagation model under the Pekeris waveguide. The structure and environmental parameters of the Pekeris waveguide in the model are shown in Table 1. The point source depth is z s =10m, the field point depth is z=15m, and the adjacent distance is 1m. The upper boundary of the waveguide is the pressure release boundary, and the lower boundary is the semi-infinite liquid space (density, sound velocity, absorption coefficient) containing acoustic absorption. The depth of the waveguide is 30m, and the density and sound velocity of seawater are respectively. The near-field Green's function (17) solved by the image source method (ISM) and the far-field Green's function (23) derive...

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Abstract

The invention discloses an FE / WSM method for structural acoustic vibration calculation under a Pekeris waveguide, and the method comprises the steps of building an elastic structure acoustic radiationmulti-physical-field coupling model under a local Pekeris waveguide through employing a finite element method, and carrying out the discrete processing of an elastic structure under a three-dimensional Pekeris waveguide; solving each coupling model through a finite difference method, and extracting a structure surface vibration data matrix under the local Pekeris waveguide; adopting a wave superposition method to carry out space optimization distribution of virtual point sound sources in the elastic structure, solving a near-field Green function based on an accurate mirror image source methodof spherical wave decomposition, obtaining a transfer matrix of each virtual source and discrete nodes on the surface of the structure, and solving sound source intensity of each near-field virtual source through inverse operation of vibration data and the transfer matrix; solving a far-field Green function through a simple positive wave disturbance theory, and calculating a monopole matrix fromeach virtual source to a field point; multiplying the sound source intensity by the corresponding single-pole matrix to obtain a sound field; and superposing and summing the sound fields generated bythe discrete virtual sources at the far-field points so as to be equivalent to a radiation sound field of a continuous elastic structure.

Description

technical field [0001] The present invention relates to the fields of acoustic radiation forecasting, acoustic measurement, underwater target detection and recognition of elastic structures in shallow sea environments, and in particular to an elastic structure under a Pekeris waveguide based on FE / WSM (finite element / wave superposition method) Acoustic calculation method. Background technique [0002] Due to the gradual shift from land to ocean in the development and protection of resources by human beings, the extensive transitional area extending from the continental shelf to the ocean is a typical shallow sea environment with a water depth of less than 200 meters. There are a large number of underwater vehicles, transportation Elastic structures such as pipelines and offshore platforms, and the research on the acoustic-vibration characteristics of elastic structures in shallow seas have attracted great attention from scholars in recent years. It plays a pivotal role in r...

Claims

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Application Information

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IPC IPC(8): G06F30/23
CPCG06F30/23Y02T90/00
Inventor 钱治文翟京生徐昕阳赵海涵王晓健刘超
Owner TIANJIN UNIV
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