ACOUSTICS_3_Damping_Acoustics_simulations

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声学仿真基础介绍

• 声学方程，声波的能量，声功率和声强； • 声级；
3）. 有限元方法及边界元方法介绍 4）. Virtual. lab-Acoustic 启动与图形界面介绍 5）. Virtual. lab-Acoustic建模基本知识
• 单位制； • 网格要求； • 单元的法线方向.
6）. Virtual. Lab 建模分析流程
Source Engine
Microphones Array Muffler
Virtual. Lab中的实现
Lw1
模拟试验中的 ISO3744场点
Lw2
传递损失: TL
TL Lwi Lwt
声衰减: NR
NR 20 log(Pn / P1)
Source
Engine
Lwi
Muffler
P Source
2. 时域2与pr频,t域 c1的2 关2 pt系r2,t： 0
时域
pr,t ~p(r) eit
k 2 2 f c c
2 ~p k 2 ~p 0
频域
求解方程都为运动学方程与结构运动学方程相同，可以将振动与声学方程进行
3. 有限元方法：
耦合求解，从而实现声振耦合的效果。
运动学方程： H i A 2Q p i F
• 映射规则是按照权重进行网格节点进行映射：
网格格式要求：
Virtual. lab-Acoustic建模基本知识
单元法向要求：
有限元网格模型的法线方向总是指向声腔的一面； DBEM的法线必须指向流体存在的一面； IBEM的法线可以指向内也可以指向外，法线方向确定了单元的正方向与负
方向，为了保证计算结果的正确性，有必要让单元法向方向保持一致。
• 在施加边界条件时一定要主要单元的法线方向，与法线方向一致是正值，否则为负值。

Simcenter3DAcoustics助力舰船声隐身设计

Simcenter3DAcoustics助力舰船声隐身设计1 背景潜艇的隐身性一般是指，在海洋中航行的潜艇，通过减小运行发出的噪声等措施，尽可能的避免被监测设备发现的特性。

随着各国的海洋实力与日俱增，不同型号和级别的潜艇层出不穷。

作为军事大国，很多国家很早之前就开始着手隐身潜艇的研发和制造。

其中，各类不同的潜艇，它们的隐身性也有所不同。

各国最尖端的隐身核潜艇中，法国自主研发的潜艇可以把自身运行发出的噪声降低至115分贝左右，然而，中国自主研发的某型号潜艇可以降低至110分贝左右。

俄罗斯和英国的战略核潜艇则可以将噪声降至更低。

然而，美国最新的攻击核潜艇“海狼”可以将噪声降低到95分贝。

这一潜艇为了增强隐身性能，整艘潜艇都被喷涂了吸收声音的橡胶和消音装置。

潜艇内的所有设备都被加装了降噪消音装置，潜艇内几乎全部大型机械使用了减震设备。

就这样，这一型号的潜艇成为了当今隐身性能最强的海底幽灵。

由于美国的隐身潜艇有着世界上最强的隐身性能，在现在的海上战争中，“海狼”级别的核潜艇很难被一般的声纳装置发现。

这样一来，隐身性能的优势展露无遗，甚至将决定战争走向。

因此，为了提高潜艇在现代海战中的胜率及生存率，必须要提高潜艇的声学隐身性能。

水下声学目标回波强度是潜艇声隐身性能的一项重要指标，因此如何利用声学仿真软件进行潜艇水下声学目标回波强度仿真对于提升潜艇的声隐身性能、提高设计效率显得尤为重要。

2 Simcenter 3D Acoustics水下声学目标回波强度仿真水下声学目标回波强度指主动声呐发射的声波与目标物反射的声波的比值，是描述水下目标回波特性的重要参数。

水下声学目标回波强度与目标的距离、方位、几何形状、材料组成、内部结构及声频率等因素有关，因此如何准确预测潜艇的水下声学目标回波强度，对于潜艇声隐身设计非常重要。

从二十多年前领导潮流的SYSNOISE软件开始，到近十多年前风靡一时的LMS b Acoustics软件，再到最近的Simcenter 3D Acoustics软件，西门子工业软件的声学软件已经经历了三代产品，其声学有限元(FEM)和边界元(BEM)已经经历了不同领域，上千个用户的验证。

LMS Virtual.Lab 电机噪声仿真计算

Example: DC Electric Motor Mechanical noise
Bearing ▪ Clearance ▪ Oil ▪ Moment
Mechanical Commutation ▪ Bar-to-bar variations ▪ Run-out
Armature/Shaft ▪ Unbalance ▪ Run-out ▪ Surface
Forces
LMS b
Mesh
16 Copyright LMS International - 2010
Load Identification
Force mapping tool: -Time to frequency: only main orders (few frequencies) -Extrusion: from 2D to 3D -Geometric mapping: from EM mesh to Structural Mesh
17 Copyright LMS International - 2010
Force generation Partnership JSOL - LMS
How many load points?
349 excitation Points?
886 excitation Points?
1847 excitation Points?
Electrical Motor EM noise Acoustic model
FEM Acoustics model
Valid up to:
8000 Hz
# nodes
12355
# elements
24 702 TETRA
HW

平面振膜换能器仿真方法研究

= ηa
∫ 1
πa2
a 0
2= πηa rdr
Fa ⋅ J2 (ka) π(ka)2 T J0 (ka)
(5)
DOI: 10.12677/mos.2020.93033
325
建模与仿真
董彩霞，陈维菲
其中， J2 (ka) 为二阶贝塞尔函数。由该式可以看出，当分母中 J0 (ka) = 0 ，即圆膜的振动频率为其共振
Modeling and Simulation 建模与仿真, 2020, 9(3), 322-331 Published Online August 2020 in Hans. /journal/mos https:///10.12677/mos.2020.93033
Figure 4. Variation of average diaphragm displacement with frequency 图 4. 振膜平均位移随频率的变化
3.2. 有效辐射面积
假设，在振动过程中，振膜的有效辐射面积会随频率变化，而整个振膜的位移在某给定频率下看作
恒定值ηa(r=0) ，根据式(4)，该值为：
林文静[2] [3]等人通过数值计算和有限元仿真的方法介绍了圆形薄膜自由振动的固有频率和固有模态；杜功焕等人[1]通过动能相等的方法介绍了圆膜在自由振动状态时的等效质量和等效弹性系数；王其申[4]通过势能相等和动能相等的方式，介绍了把自由振动状态下的分布参数系统等效成集中参数系统的两种方法。
本文在前人研究[1]-[9]的基础上，通过“等效”的方法，对圆膜在强迫力作用下振动时的等效集中参数及振动规律进行了理论研究，并以平板扬声器作为研究对象，使用数值计算和电路仿真的方法对其声学性能进行了计算和仿真，同时，使用 Klippel 及 AP 测试系统对其声学性能进行了测试。仿真与实测结果较高的吻合度表明，该方法对分布参数振动系统的研究具有一定的参考价值。最后，本文对仿真与实测结果的差异进行了分析，可以作为进一步研究的参考方向。

LMSVirtualLabAcousticsA新功能介绍

L M S V i r t u a l L a b A c o u s t i c s9A版新功能介绍作者：LMSb是由以振动噪声、疲劳、操稳性工程解决方案着称的LMS际公司推出的全球第一个功能品质工程集成解决方案。

b提供集成的多学科软件平台用于分析和优化机械系统的性能，包括结构完整性，噪声及振动，耐久性，系统动力学，操稳性及平顺性、多体动力学以及其它属性。

b包括所有关键过程步骤及所需的技术，可以远在进行昂贵的加工和实物样机之前对每个关键属性进行从头到尾的评价，并使仿真设计真正迈向功能品质属性为目标的功能化设计，大大提升了仿真设计在产品开发中的功能性和指导性。

bAcoustics是b的拳头产品，是市场上最先进的振动声学和流体声学分析软件，从诞生开始多年来一直是声学领域排名第一的仿真软件，也是声学领域中公认的工业标准。

bAcoustics提供了从振动噪声到流体噪声，从声辐射到声-振耦合，从部件级到系统级，从低频到中高频，从前处理、求解器直到结果后处理的一个完整的解决方案。

在2009年11月正式推出的9A版本中，推出了开创性的有限元和边界元求解方案。

下面我们为大家做详细的介绍：完美匹配边界层技术：Fem-PMLbAcoustics9A版本中的FEM-PML完美匹配边界层有限元技术则在将有限元求解速度提高10+倍的同时，还极大地拓展了声学建模的灵活性和仿真应用范围。

FEM-PML技术通过在有限元模型外部建立声吸收层，可以完美解决有限元外场声辐射的问题。

FEM-PML技术不需要像无限元一样需要一个规则的外表面（球形或者椭球形），可以设定在离有限元模型非常接近的位置。

这样可以大大降低一般外场声辐射的模型自由度数，提高计算速度。

可以认为，FEM-PML是无限元的替代技术。

有限元/无限元搭建的发动机模型FEM-PML技术搭建的发动机模型拓展的快速多级边界元技术在8B版本中推出的FM-BEM快速多极边界元技术使得超大规模边界元模型的求解成为现实，并将分析频率范围直接拓展到高频：该模块运用迭代技术来求解边界元方程，通过基于多极扩展和多层次分级蜂窝子结构的高级算法，使得求解边界元方程的计算速度极大提高，同时内存消耗极大缩减。

simtri.simplis仿真_中文教程

Simetrix/Simplis仿真基础近4年开发电源的过程，在使用仿真软件的过程中，对仿真渐渐有了个了解，仿真不能代替实验。

仿真软件显示电路不能工作，而实际确能工作，仿真不收敛，而实际电路永远不会不收敛。

但是仿真软件可以测试未知电路，可以验证自己的想法，甚至大大缩短开发过程，在你仿真的过程中，也可以更深入的理解开关电源的拓扑结构，控制模式等，假如你要实验一个电路，发现库里没有现成的IC,在自己搭建IC之后，你对整个IC具体是如何运作的必定了解的非常清楚。

如果你的模型足够精确，你可以得到和实验室非常接近的结果。

如果你的电路是错误的，你也不用担心“炸机”的危险。

Simetrix/Simplis是我个人比较喜欢用的一款仿真软件，相对与功能强大的SABER, Simetrix/Simplis具有操作简单，容易上手，速度快等特点，用来实验开关电源的各个功能电路非常不错，精通之后，也能进行更复杂的仿真实验，比如开关电源的损耗分析，环路分析，大信号分析，IC设计等。

“只要你能想到的，你就可以用电路实现！”虽然这几年一直在接触这款软件，但离“精通”还相差很远，但我想利用它简单易学的特点，让更多的人了解使用它，对实际开发有所帮助。

并希望引出玉来，使大家共同提高。

我打算先说一下软件操作过程，再举几个简单的实例，供大家参考。

由于水平有些，只能说这些基础的东西。

先说一下目录1.基础操作：放置元件2.导入PSPICE模型3.瞬态分析，DC分析，AC分析，参数扫描4.自建子电路，元件库5.用SIMETRIX仿真开环BUCK。

6.用SIMPLIS 仿真BUCK电路：POP分析，AC分析。

7.两个简单的实例：桥式整流带恒功率负载—表达式的应用填谷PFC PF值计算-波形的分析和处理更深入一点的实例如电流模式反激电路。

准谐振反激电路。

单极反激PFC电路。

LLC电路等。

做好后会和大家分享。

1.放置元件。

先打开程序，点击File——New Schematic,建立新电路图点这两处地方可以放置元件基本的元件如DC电源，波形发生器电源，分段源，受控源，电阻，电容，电感，变压器，MOS管，三极管，二级管，稳压管，压控开关，地，电压探头，电流探头，运放等都能找的到，如上图，也可以从Place——From Model Library菜单中找到更多的元件，如3842，TL431等。

几个耦合的例子

一般说来，ANSYS的流固耦合主要有4种方式：1，sequential这需要用户进行APDL编程进行流固耦合sequentia指的是顺序耦合以采用MpCCI为例,你可以利用ANSYS和一个第三方CFD产品执行流固耦合分析。

在这个方法中，基于网格的平行代码耦合界面(MpCCI) 将ANSYS和CFD程序耦合起来。

即使网格上存在差别，MpCCI也能够实现流固界面的数据转换。

ANSYS CD中包含有MpCCI库和一个相关实例。

关于该方法的详细信息，参见ANSYS Coupled-Field Analysis Guide中的Sequential Couplin2，FSI solver流固耦合的设置过程非常简单，推荐你使用这种方式3，multi-field solver这是FSI solver的扩展，你可以使用它实现流体，结构，热，电磁等的耦合4，直接采用特殊的单元进行直接耦合，耦合计算直接发生在单元刚度矩阵一个流固耦合的例子length=2width=3height=2/prep7et,1,63et,2,30 !选用FLUID30单元，用于流固耦合问题r,1,0.01mp,ex,1,2e11mp,nuxy,1,0.3mp,dens,1,7800mp,dens,2,1000 !定义Acoustics材料来描述流体材料-水mp,sonc,2,1400mp,mu,0,!block,,length,,width,,heightesize,0.5mshkey,1!type,1mat,1real,1asel,u,loc,y,widthamesh,allalls!type,2mat,2vmesh,allfini/soluantype,2modopt,unsym,10 !非对称模态提取方法处理流固耦合问题eqslv,frontmxpand,10,,,1nsel,s,loc,x,nsel,a,loc,x,lengthnsel,r,loc,yd,all,,,,,,ux,uy,uz,nsel,s,loc,y,width,d,all,pres,0allsasel,u,loc,y,width,sfa,all,,fsi !定义流固耦合界面allssolvfini/post1set,firstplnsol,u,sum,2,1fini再给大家一个实例！考虑结构在水中的自振频率：例子是一加筋板在水中的模态分析。

【精品】Virtuallab声固耦合的隔声量仿真分析教程

【关键字】精品FEM Direct Vibro-Acoustic Analysis Case Tutorial Objective:The goal of this tutorial is to calculate the acoustic response of a glass/PVB plate (a laminated safety glass with a Polyvinyl butyral layer in between).The tutorial includes using the following analysis cases:•Structural Modal case•Direct Structural Forced Response•Direct Structural Vibro-Acoustic Response•Transmission LossThe model contains a Visco-elastic frequency-dependent material.Pre-Requisites:Software Configurations that are needed to run the tutorial:•Licenses to set up the case in LMS b: "Desktop (VL-HEV.21.1 or equivalent)"and "Finite Element Acoustics (VL-"•When solving the acoustic response case, the license for product "LMS bFEM Vibro-Acoustics Structural Solver VL-VAM.45.2" is needed.•Solving the Random Post-processing case to get the Transmission Loss curve willrequire the license for "Random Vibro Acoustic Analysis (VL-"Tutorial Data Files:StructuralGroups.xmlSAFyoung.xlsLaminatedStructure.bdfFPmesh.bdfAMLsender.bdfAMLreceiver.bdfAcousticGroups.xml[All data files can be found on the APPS n DOCS DVD, in an archive called VAM_DirectVA-TL. For ease of use, it is best to copy all files to a local folder.]STEP BY STEP Tutorial:STEP 1After starting LMS b, create a new document in the Acoustic Harmonic FEM Workbench (Start Acoustics Acoustic Harmonic FEM).STEP 2Select File Import from the main menu. [The Import command can also be selected from the contextual menu of the Links Manager, by right clicking]A file selector window appears allowing you to specify the file type and the file name. [For more details, see ]Select the file type NASTRAN Bulk File (*.bdf, *.NS, *.nas, *.dat) and browse for the file LaminatedStructure.bdf and click the Open button. A new dialog box appears requesting the selection of data that needs to be imported from the file. The data entries that are not available in the file are grayed out.Select in Split into Multiple Mesh Parts under Mesh Creation and set the unit system to Meter, Kilogram, Second, click the OK button.STEP 3Next, the different structural materials will be defined. The two outer layers of the panel are made of Glass. To incorporate the 2% structural damping of this material, it will be modeled as a viscoelastic material with a constant complex Young modulus. The inner layer is made of PVB.Insert Materials New Materials New Viscoelastic Material...[Right-click on the Materials feature in the Specification Tree New Materials New Viscoelastic Material]Define the materials as follows:The PVB material at the center of the windshield has strong frequency dependent stiffness properties and is nearly incompressible. The frequency dependency can be incorporated in a viscoelastic material using an edited load function. The values can be imported from the Excel document SAFyoung.xls as follows:Check Frequency Dependent, and right-click the input field.Select New Function.In the Attributes tab, enter as Name Young’s modulus PVB.In the Values tab, click the Import a file button, and browse to the excel file to select it.Switch the Data Format to Linear Amplitude/Phase (deg) because the file contains the values like that. Click the Import button.Click the OK button of the Function Editor GUI.Click the OK button on the Material GUI.On the Edited Load Function Set, create (using the context menu) a 2D display of type Complex(Edited Load Function) on the Young’s modulus and check the curve:STEP 4Defining two Structural 3D properties for Glass and PVB, applied to the structural groups Glass (with the defined material Glass) and PVB (with the defined material PVB).Insert Properties New Structural Properties Create 3D-Property[Right-click on the Properties feature in the Specification Tree New Structural Properties Create 3D-Property]Before the following steps please make sure the Mesh Parts are defined as types:PROPERTY0 – StructuralGlass – StructuralPVB – StructuralThis can be done by going to Tools Set Mesh Parts Type[Right-click on the mesh in the Specification Tree, Set Mesh Part Type Set as Structural Mesh Part]STEP 5In the next step, the model mesh will be imported from two Nastran input files. They each contain a mesh on which we will apply an AML property (Automatically Matched Layer), one on the receiver side, and one on the sender side.:File Import Acoustic Mesh Model Mesh..., and select the file AMLreceiver.bdf Use Meter, Kilogram and Seconds units, and include the materials and properties. Similarly, import AMLsender.bdf.At this point the mesh parts type definition window should look like this:STEP 6Inserting the New Material and properties for the new imported meshesInsert a new Acoustic material as follows (use the default values for air):Insert also a New Fluid Property. Call it also air, use the just defined material 'Air', and apply it to the two Acoustic mesh parts (Sender and Receiver side).STEP 7To facilitate the creation of the structural and acoustic model, some element groups have been predefined in xml files. To import these groups, first create mesh group sets.Insert a New Group Set, either from the contextual menu or with Insert Mesh Grouping Group Set....By right clicking the Group Set feature in the Specification Tree, insert a mesh group named Structural Groups, and in it import the 5 groups from the file StructuralGroups.xml. Right-click the Group Set, and use Mesh Grouping Group Selection Dialog…:Similarly insert a mesh group named Acoustic Groups, and in it import the 4 groups from the file AcousticGroups.xmlRight-click the group set, and use again Mesh Grouping Group Selection Dialog…:Step 8Save the analysis, but without closing.SETTING UP THE ACOUSTIC CASESStep 1Insert a new acoustic automatically matched layer property to take into account thesemi-infinite extent of the sender and receiver rooms. Insert a new AML property byright-clicking Properties, use New Acoustic Properties Automatically Matched Layer Property....Apply it to the two Acoustic groups AML Receiver and AML Sender. Switch the Radiation surface to User Defined, and select the AML Receiver group.Step 2Insert a Direct Vibro-Acoustic Response Analysis Case to compute the structural response and acoustic pressure fields in both the sender and receiver acoustic domains for each of the distributed plane wave excitations:To perform this calculation use No Load function Set and No Load Vector Set.Create new sets for all the rest.STEP 3Expand the Direct Vibro-Acoustic Response Analysis Case from the Specification Tree, right-click the Boundary Condition Set and use Acoustic Sources Distributed Plane Waves... with a Refinement Level of 2, a Radius of4m, and an Acoustic Pressure on 1Pa. The plane waves will be used to excite the system and to calculate the transmission loss characteristics of the panel.Since the panel is not aligned with the xy plane, this coordinate plane cannot be used to define the location of the plane wave sources. So, for the Half Space Plane select Plane defined by Group and select the acoustic group Coupling Sender.Select the Negative Half Space side.Click the OK button to generate a set of 12 spatially distributed plane waves.By now the model should look similar to this:Step 4We will now restrain the border of the glass panel.Right-click the Restraint Set, add an Advanced Restraint on the 3 Translational DOFs, and use as support the Structural Group BCs.Step 5Coupling surface definition will be used to couple the upper and lower surfaces of the panel to the envelope surface of the acoustic cavity. When setting the Coupling Surface, the coupling between the structure and the fluid is on both sides.To correctly define the two-sided coupling in a transmission loss calculation, two coupling surfaces need to be created. From the Coupling Surface Set.1 feature, double-click the Coupling Surface Set.1, and add the two surfaces: Structural Group CouplingSender and Acoustic Group Coupling Sender. Use a tolerance of 10mm and select as Coupling Type One side. Click the Apply button.Do the same for the Receiver Side in the end you should have two Coupling surfaces:Step 6Double-click on the Direct Vibro-Acoustic Response solution to update the analysis parameters. In the current tutorial, the response at the center frequencies of the third octave bands between 160Hz and 2000Hz will be analyzed. In the Result Specifications tab, select User Defined values for the Argument Axis Definition and remove the standard analysis frequency range. Add a new frequency range definition and select a Logarithmic Step definition with a starting frequency of 160Hz, an ending frequency of 2000Hz and a step of 1.8. Click the OK button to add the frequency range definition.Request Vector results at Field Points and for the Acoustic Potentials. No need to solve for Structural Displacements for now.Adjust the Solving Parameters. If your system is set up for parallel processing (see the Advanced Acoustic Installation manual), try one of the Parallelism types. Use the Direct solver.Adjust also the Job and Resources, e.g. to use multiple threads.Leave the Output Sets empty, meaning that results will be computed wherever possible.Step 7Update the Direct Vibro-Acoustic Response Solution to compute the acoustic pressure fields and structural deformations. This will take a while, as there are 23 frequencies and 12 load conditions. Save your model.Step 8Displaying the resultsOnce the computation is finished, right-click the Direct Vibro-Acoustic Response Solution Set.1 feature and select Generate Image from the contextual menu.[or select the solution feature and click the Generate Image toolbar button.]The Image Generation dialog box will appear, select the Pressure.Double-click the image feature in the Specification Tree, and in the Occurrences tab select the for example the first Load Condition (meaning the loading by the first distributed plane wave source) and set the frequency at 508Hz, click the OK button. For better visualization you can hide the Nodes and Elements feature, and the Boundary Conditions feature (with its plane wave sources).You can also display the 2D image curve for the Acoustic Power on the Kirchhoff surfaceRight-click the Direct Vibro-Acoustic Response Solution Set.1feature and select New Function Display... from the contextual menu. The New Function Display dialog box will appear requesting you to select the different display images.[Also you can use the button from the toolbar and select the Solution Set feature. A third possibility is to use the menu Insert 2D/3D Images New Function Display]Select the 2D Display from the list and click the Finish button.A new window, containing X- and Y-axes along with the Select Data dialog box will now appear. In the Select Data dialog box, select Kirchhoff Surface Radiation: S and click the Display buttonAs each of the distributed plane wave sources are independent, the sound power can be obtained by simply adding the individual contributions. So, select all 12 Data Cases, and check the option Sum over data cases.Switch the x-axis format to Octaves, and the Y-axis to dB(RMS). You can use dot markers for the curve by right-clicking it, using the Options... command in its context menu, and then changing the settings in the Visualization tab.Save your modelStep 9To get the transmission loss curve, we need to divide the total acoustic power on the receiver side by the total power on the sender side. Before we can do that, we need to combine the individual cases (one for each distributed plane wave source) to get the total power curves.Insert a Random Post-processing Case with Insert Other Analysis Cases Random Post-Processing Case...Refer to the solution of the previous response case, and select to process for a Cross Power Set with Unitary Uncorrelated Load Cases:Update its solution using the context menu on its solution feature Random Response Solution Set.X. This will go fast.Right-click the sub-solution Global Indicator Set.X and create a New Function Display on it. Select the 2D Display as scenario, and click the Finish button.A 2D display window will appear with the Select Data dialog box open. In the General tab, switch the drop-down selector to Transmission Loss, and select the entry Coupled Surface:S and click the Display button.You can see a TL value of 30.461911 dB for the 319.996 Hz octave band:Theory for Panel Transmission LossCalculation of Transmission Loss using Vibro-Acoustic FEMThis topic describes how to set up a model and the computation to compute the Transmission Loss (e.g. for a panel) using the LMS b tools.Step1.Import of an Acoustic and Structural meshand a structural mesh with the modal data in the Acoustic Harmonic FEM workbench. There is no need to have a field point mesh.Step2. Create a New Acoustic PropertyDefine the Acoustic Properties including fluid properties and possible impedance on the panel. Create an property for the source room on all faces that are not coupled to the panel and not touching the joined wall. The wall must be a zero velocity boundary condition. Also create an Automatically Matched Layer (AML) on the anechoic room side, which is defined as a Kirchhoff surface.Step3. Insert the boundary conditionCreate an acoustic boundary condition by selecting Insert Acoustic Boundary Conditions and Sources Acoustic Boundary Condition and Source Set… from the main menu. The Boundary Condition Set Creation dialog box appears as shown in the image below:Click the OK button to close the dialog box. A new Acoustic Boundary Conditions and Sources feature appears in the Specification Tree as shown in the image below:Now, similarly add to the Acoustic Boundary Condition and Sources an acoustic source of type in the source room.Step4. Insert a Vibro-Acoustic Response and Random Post-Processing Analysis CaseInsert the Modal-based by selecting Insert FEM Analysis Cases Modal Based Vibro-Acoustic Response Analysis Case… from the main menu, or click the Create aModal Based Vibro-Acoustic Response Analysis Case… button from the FEM AnalysisCases toolbar. Define the Mesh Mapping and select the structural shells and the two groups of acoustic faces (one in the source room and one in the receiver room). Compute theModal-based Vibro-Acoustic Response Analysis case. It will compute the Incident Power and the Radiated Power for each source.Similarly, insert a, and Compute it. It will compute the Total Powers and store it in asub-solution called Global Indicator Set as:•Total Incident Power, having Physical Type as INPUT_POWER and Response ID asCoupled Surface:S.•Total Power radiated by the Acoustic Mesh, having Physical Type asACOUSTIC_POWER and Response ID as Kirchhoff Surface Radiation:S.•If you have a field point mesh which is not needed to compute the Transmission Loss), it will also compute the Total Power on the Field Point Mesh having Physical Type asACOUSTIC_POWER and Response ID as Field Point Mesh:S.The Random Response Solution Set computes also the Transmission Loss with the following formula:Where,is the Incident Poweris the Radiated PowerStep5: Post-ProcessingStandard results will be post-processed on the analysis cases.The Incident Power, Radiated Power and Transmission Loss are stored as Expressions, Load Functions by the Global Indicator Set, and can be displayed in a 2D Function Display.The Transmission Loss will be stored with Physical Type as "ABSORPTIVITY" and Response ID as "Coupled Surface:S"Manual calculation of Transmission Loss by using Edited Load FunctionStep1.Insert an .To insert an Edited Load Function, select from the main menu Insert Functions CreatorEdited Load Function… or use the Create an Edited Load Function button available in the Functions Creator toolbar.Step2.Import Kirchhoff Surface Radiation:S function from Global Indicators of the Random Post-Processing Solution Set of the Acoustic document. Take only the Real Part.Step3. Again, import the function Acoustic Power on Field Point Mesh:S from Global Indicators of the Random Post-Processing Solution Set of the Structural document. Take only the Real Part and Amplitude of that Part.Step4. Multiply this function with 0.5. As the actual incident power is half the power through the field point mesh. This is because the incident pressure is imposed as total pressure on the wall.Step5. Now, divide these two functions and take the Log of that function and finally multiply it with 10.Step6.To visualize the computed Transmission Loss, right-click the Edited load function in the Specification Tree and select the New Function Display… option from the contextual menu. Select 2D Display from the list and click the Finish button. From the Select Data dialog box select Transmission Loss using the drop-down menu.BEM Symmetry Plane SetThe mathematical formulation of the Boundary Element method leads to dense matrices, with the consequence that a linear increase in model size N (number of nodes and elements, or more generally, number of DOFs) leads toA parabolic increase (order N**2) for the BEM matrix storage requirementsA cubic increase (order N**3) for the BEM matrix solution timeTherefore, it is very advantageous to exploit symmetry characteristics in the geometry of the sound-radiating structure to the full extend. If you need to model only one-half, one-quarter or one-eighth of a vibrating structure, this leads to a drastic reduction in memory requirements and solution time for the problem at hand.The Symmetry Plane Set command allows you to define the acoustical symmetry oranti-symmetry conditions with respect to planes that are parallel to the coordinate axis planes (XY, YZ or XZ). The Symmetry Plane or Baffle will be correctly visualised, if the Mesh is Acoustic (Mesh Type: Acoustic) and a Mesh Preprocessing Set is inserted in the Specification Tree.To insert a new Symmetry Plane Set, click the Insert/Edit a Symmetry Plane Set button in the Acoustic Model Definition toolbar or select Insert Symmetry Plane Set from the main menu. A new dialog box will appear as shown in the image below.Figure: Symmetry and Anti-Symmetry Plane dialog•Planes X, Y and ZThese planes are defined by their position along the perpendicular direction withrespect to the coordinate axis plane; for instance, the X-symmetry plane X=1000mm defines a symmetry plane parallel to the YZ plane and passing through the point(1000,0,0).Although the geometry should always be symmetrical in order to allow the definition of symmetry and anti-symmetry planes, the actual acoustical conditions can besymmetrical (identical) or anti-symmetrical (opposite) with respect to the planedepending on the type of plane selected. The following table summarizes the effect of defining symmetrical or anti-symmetrical conditions for both acoustical and structural boundary conditions:Figure: Symmetry and Anti-Symmetry conditions summaryUp to three mutually perpendicular symmetry or anti-symmetry planes can be defined simultaneously. Of course, only one symmetry or anti-symmetry plane can be defined parallel to each coordinate axis plane XY, YZ or XZ.Since acoustical symmetry implies zero normal velocity, defining a symmetry plane is acoustically equivalent to the presence of a rigid, 100% reflecting floor. In other words, if you are modeling a situation where the sound-radiating structure is located on a hard floor, e.g. the concrete floor of a semi-anechoic chamber, the presence ofthis floor can be represented simply by a symmetry plane.Conversely, since acoustical anti-symmetry implies zero acoustic pressure, defining an anti-symmetry plane is acoustically equivalent to the presence of pressurerelease surface. This kind of surface can be used to model free surfaces like awater-air interface. E.g., if you need to model the acoustic radiation into water from a submarine at a certain depth, you can model the presence of the sea surface above the submarine by defining an anti-symmetry plane.When defining these kinds of planes, they are represented by colored square surfaces. You can also change the colors of the planes by selecting Tools Options AcousticsDisplay tab.•By default, symmetry planes are represented by semi-transparent bright greensquares with an opaque border as shown in the image below.•By default, anti-symmetry planes are represented by semi-transparent bright bluesquares with an opaque border as shown in the image below.The presence of these surfaces will also have an important impact on the type of boundary conditions that are created by the Acoustic Mesh Preprocessing operation.•BaffleThis functionality is useful for handling the acoustic transparency problems and allows you to compute the insertion or transmission loss. It is only available in the AcousticHarmonic BEM Workbench when the model type is Indirect type. The baffle isrepresented as a symmetry plane but with red color as shown in the image below.The Transmission loss and Insertion loss can be computed in term of pressure or acoustic power. This is quite straightforward when it is done on the pressure, but some postprocessing is needed when it is done on the power. The Incident Power and Transmitted Power can be calculated by using the following formulae.Incident PowerUsually for the transmission loss computation, an acoustic diffuse field is defined on one side of the baffle. The Incident Power can be computed with the following formula:where Prms is the diffuse field acoustic RMS pressure and S is the surface of the structure impacted by the incident diffuse field. This is valid for a diffuse field generated by a sum of文档来源为:从网络收集整理.word版本可编辑.欢迎下载支持.plane waves. The total input power is the sum of the individual source power. This can be easily computed in an edited load function.Transmitted PowerThe Transmitted Power can be computed by defining a hemispherical field point mesh almost touching the baffle and computing the field response. The total Transmitted Power will then be computed in the random post processing case. When updating the solution, if there is acoustic power through field point mesh available in the input solution, the total acoustic power will be computed with the following equation:where Wt is the total acoustic power, NLC is the number of pseudo load-cases, are the singular values (Virtual Autopowers) and Wi is the acoustic power for load case i.此文档是由网络收集并进行重新排版整理.word可编辑版本！。

COMSOL Multiphysics 在声学领域的应用案例集

算例：1.声学器件2D轴对称喇叭单元电磁-声-固耦合分析这是一个动态电磁式圆锥形扬声器模型，通常用于中低频段声音重放，电磁场模块的小信号分析计算静电力和静态的音圈阻抗，声固耦合应用模式分析喇叭振膜的振动以及声波的辐射，最外层采用完美匹配层边界条件（PML）模拟无限大空间，输出结果包括随频率变化的灵敏度曲线和阻抗特性曲线等。

模型来源: Acoustics_Module/Industrial_Models/loudspeaker_driver。

压电声学传感器压电传感器能把电信号转换成声压辐射，反过来，也能把声场压力转换成电信号。

这种换能器采用压电材料和声场应用模式，在声场-结构交界面处考虑到了结构变形对声场的加速度影响以及声场对结构的反向压力的作用。

该模型广泛应用于阵列式麦克风，超声传感器、超声探伤、无损检测、声纳、成像等。

利用COMSOL Multiphysics的拉伸耦合变量，仅需2D 的计算即可得到3D的结果数据。

模型来源: Acoustics_Module/Tutorial_Models/piezoacoustic_transducer声表面波（SAW）气体传感器特征模态分析该案例研究了SAW气体传感器的共振频率，声表面波(SAW)是能够沿着材料表面传播的波，它的振幅随材料深度按指数规律迅速衰减。

SAW器件在很多电子元件中都有广泛的应用，例如滤波器，振荡器和传感器等。

SAW由一个相互交叉的换能器构成(IDT)，换能器刻蚀在压电LiNbO3 (铌酸锂) 基底上，并覆盖一层薄的聚异丁烯 (PIB)膜，当暴露在空气中时，PIB 膜选择性的吸收CH2Cl2 (二氯甲烷, DCM) ，PIB 膜的质量随之增加，从而导致特征频率向低频扩展。

模型来源：Acoustics_Module/Industrial_Models/SAW_gas_sensor。

光声传感器特征模态光声器件广泛用于检测气体化合物的浓度，它是基于器件的光共振吸收现象，气体分子的非弹性碰撞将激发能量转换为热能，样品的调制照射会引起周期性的压力变化，该压力变化可以被光声传声器检测到，其信号检测灵敏度依赖于光声器件的几何形状，利用声学器件的共振特性可以改善其灵敏度。

Acoustic Parameter Editing Method, Acoustic Parame

专利名称：Acoustic Parameter Editing Method,Acoustic Parameter Editing System,Management Apparatus, and Terminal发明人：Akihiro MIWA申请号：US17455731申请日：20211119公开号：US20220172745A1公开日：20220602专利内容由知识产权出版社提供专利附图：摘要：An acoustic parameter editing method is used in a management apparatus and a terminal. The management apparatus includes a first parameter memory configured toindicate an acoustic parameter and is connected to a sound signal processing engine configured to perform a sound signal processing by reflecting the acoustic parameter. The terminal includes a second parameter memory having the same memory structure as that of the first parameter memory in at least apart thereof. The management apparatus receives the acoustic parameter to update the first parameter memory. The terminal receives the acoustic parameter to update the second parameter memory when not connected to the management apparatus, and to update the first parameter memory when connected to the management apparatus. When the first parameter memory is updated, the terminal updates the second parameter memory in synchronization with the updated first parameter memory.申请人：Yamaha Corporation地址：Hamamatsu-shi JP国籍：JP更多信息请下载全文后查看。

声学仿真及在工程中的应用

FFT & MSC Software Confidential
5
频率域仿真和时间域仿真
• 频率域仿真：针对不随时间变化的现象，线性问题，计算频率响应函数和传递函数
• 时间域仿真，瞬态仿真：可针对瞬态随时间变化现象，非线性声学激励，发动机（动力总成）加速过程，冲击，碰撞现象等
FFT & MSC Software Confidential
Time domain simulation SPL (time domain)
FFT & MSC Software Confidential
18
Engine Slap Sound Analysis
• Engine Slap Sound Analysis
– The Sound from contact between Cylinder inner wall and Moving Piston
•
• •
TM
DGM Etc.
基于有限元方式
FFT & MSC Software Confidential
3
声学仿真历史发展
• 21世纪前：边界元方式模型规模： x0,000
• 目前主流方式：
有限元方式模型规模: x00,000 to x0,000,000
• 发展方向：
有限元： FEM & DGM 模型规模 x0,000,000 to x00,000,000 大规模问题，高频率问题
声学仿真及在工程中的应用
周泽声学仿真业务发展经理
2015年5月27日
FFT & MSC Software Confidential
1
Actran 软件及技术特点介绍

lms virtuallab acoustics 声学

lms virtuallab acoustics 声学简介LMS b Acoustics（简称为b Acoustics）是一种声学仿真软件，它是由LMS公司开发的。

b Acoustics提供了一种强大的工具，用于预测和优化产品在各种声学环境下的性能。

本文将介绍b Acoustics的基本概念、功能和应用。

功能b Acoustics提供了一系列功能，用于分析和优化产品的声学性能。

以下是其中一些主要功能：声学模拟b Acoustics使用有限元方法（FEM）进行声学模拟。

用户可以创建复杂的声学模型，并应用各种边界条件和激励来模拟不同的声学环境。

该软件能够精确地预测声学场的分布、声压级、振动模式等参数。

声学优化b Acoustics提供了优化工具，用于改善产品的声学性能。

用户可以设置优化目标，例如减少噪声、提高声质量等，并利用软件的优化算法自动搜索最佳解决方案。

通过优化，产品的声学性能可以得到显著提升。

声学材料建模b Acoustics包含了广泛的声学材料数据库，用户可以根据其产品的特性选择合适的材料。

此外，软件还提供了材料性能预测工具，用户可以根据材料的物理特性和声学特性进行定制建模。

声学设计评估b Acoustics可以进行声学设计评估，帮助用户优化产品的声学性能。

通过对不同设计方案的模拟和比较，用户可以选择最佳的设计方案，并预测其声学性能。

应用b Acoustics广泛应用于各个领域，以下是一些典型的应用场景：•汽车工业：b Acoustics可以用于汽车噪声和振动控制，以改善车辆的舒适性和安静性。

它可以预测和优化车内外噪声水平，并评估不同材料和设计方案对噪声的影响。

•航空航天工业：b Acoustics可用于航空航天器件和结构的声学设计和优化。

它可以模拟飞机发动机噪声、飞机机身振动等，并优化设计以减少噪声和振动。

•电子产品：b Acoustics可以应用于电子产品的声学设计和优化。

通过模拟和分析，可以改善电子设备的音质和降低噪声水平，提供更好的用户体验。

NI ELVIS II系列产品规格说明说明书

Modes ..............................................Analog edge triggering, analog edge triggering with hysteresis, and analog window triggering
Arbitrary Waveform Generator/Analog Output
Number of channels.........................2
DAC resolution................................16 bits
DNL.................................................±1 LSB
Maximum working voltage for analog inputs (signal + common mode) ................ ±11 V of AIGND
CMRR (DC to 60 Hz) ..................... 90 dB
Source..............................................AI<0..15>, ScopeCH0, ScopeCH1
Small signal bandwidth (–3 dB)......1.2 MHz
Input FIFO size................................4095 samples
Scanlist memory ..............................4095 entries
Data B signal stream, programmed I/O

声疲劳仿真计算实例-virtual.lab版

Step 4 Carry out the acoustic preprocessing
Insert->Acoustic mesh preprocessing set.
Double click the Grid Support in the tree and the select the acoustic mesh. Right click on the Acoustic Mesh Preprocessing Set and select Update.
声疲劳仿真计算实例
Acoustic fatigue
By Li Zenggang
Mobile: Email: forengineer@
Step 1 Import the structure and acoustics meshes
Start->Acoustics->Acoustic Harmonic BEM File->Import. First select nastran input file
Step 5 Define the material and property
Insert-> Materials->New Materials ->New fluid
Material. Accept the default value. Change the Name to air. Insert ->Properties->New Properties -> New acoustic fluid property. Select the acoustic mesh and the fluid material from tree.

一种低延迟三电平APF的方案设计及仿真研究

一种低延迟三电平APF的方案设计及仿真研究刘光亚;朱晓蒙;李响【摘要】为实现谐波检测低延时与补偿电流跟踪控制的高实时性,以此提升三电平有源电力滤波器(active power filter,APF)的动态响应性能与稳态滤波精度.设计一种低延迟三电平APF系统方案:用移动窗积分算法降低ip-iq检测中常用二阶巴特沃斯(butterworth)低通的延迟时间;提出运用基于等距结点牛顿后差插值的瞬态重复校正预测控制方案,实现传统电压空间矢量脉调(space vector pulse width modulation,SVPWM)与无差拍算法的复合控制策略,消除传统SVPWM控制拍数的延迟.Matlab对系统方案仿真对比:三电平APF系统采用低延迟方案时启动阶段响应快且稳,负载突变后过渡响应快,稳态总谐波畸变率(total harmonic distortion,THD)为1.36％,具备明显优势.研究表明:低延迟三电平APF系统方案通过降低谐波检测延迟与电流跟踪控制延迟,提高了APF系统的滤波性能.【期刊名称】《科学技术与工程》【年(卷),期】2016(016)017【总页数】7页(P192-198)【关键词】三电平有源电力滤波器;低延迟;移动窗积分;牛顿后差插值预测;无差拍;电压空间矢量脉调【作者】刘光亚;朱晓蒙;李响【作者单位】湖北工业大学电气工程学院,武汉430068;湖北工业大学电气工程学院,武汉430068;湖北工业大学电气工程学院,武汉430068【正文语种】中文【中图分类】TM761.2现阶段电力电子设备应用广泛，而属于典型非线性负载的电力电子设备可使电网受到谐波污染，谐波治理与无功补偿装置在此环境下得到了应用和发展[1]。

针对无源滤波器的局限性研究出的有源电力滤波器可主动消除谐波与补偿无功，动态性能优越[2]。

实时准确的谐波检测法和实时高性能的电流控制方案一直是APF研究的热点及难点，因此构建一个低谐波检测延迟与可消除补偿控制滞后的有源滤波器系统方案具有现实意义。