双层墙中填充空气或者吸声材料该怎么设置
小弟刚开始设计隔声的领域，问一个超弱的问题，用virtual lab计算双层墙的隔声量，如果在双层墙中填充空气或者吸声材料，中间那层空气和吸声材料应该怎么设置呢？ 如果是空气的话，简单啊，你就是有限元模型，定义了空气的流体材料属性就可以了。如果你中间有吸声材料，也可以直接建立其有限元模型的，然后定义吸声材料属性就行，如下图。
superxjw 发表于 2013-2-25 22:04 static/image/common/back.gif
如果是空气的话，简单啊，你就是有限元模型，定义了空气的流体材料属性就可以了。
如果你中间有吸声材料， ...
太感谢了太感谢了 greed777 发表于 2013-2-25 22:09 static/image/common/back.gif
太感谢了太感谢了
不客气，VL是很好用的，没事的话你把这些菜单都点着看看，慢慢就熟悉了。 本帖最后由 greed777 于 2013-2-26 17:21 编辑
superxjw 发表于 2013-2-26 08:13 http://forum.chinavib.com/static/image/common/back.gif
不客气，VL是很好用的，没事的话你把这些菜单都点着看看，慢慢就熟悉了。
问一个问题，为什么我在进行了“acoustic mesh preprocessing set”这个操作之后，再去进行添加“coupling surface”命令的时候就会跳出对话框,上面写着“selected acoustical groups do not contain any valid mesh entity. They should contain 3D faces or 2D elements form acoustic envelope.” 但是如果不进行“acoustic mesh preprocessing set”这个操作的话，就不会显示不能耦合。
greed777 发表于 2013-2-26 17:17 static/image/common/back.gif
问一个问题，为什么我在进行了“acoustic mesh preprocessing set”这个操作之后，再去进行添加“coupl ...
仔细检查步骤 应该是你前面少了什么步骤了 斑竹， 你能否试一下我试过许多次中间加吸声材料或者空气 都是报错 complexman2005 发表于 2013-2-28 16:57 static/image/common/back.gif
斑竹， 你能否试一下我试过许多次中间加吸声材料或者空气 都是报错
什么中间加吸声材料或空气？ 就是双层钢板或者双层墙 中间夹着空气或者吸声材料如何采用AML方法进行计算隔声量呢？ complexman2005 发表于 2013-3-1 11:35 static/image/common/back.gif
就是双层钢板或者双层墙 中间夹着空气或者吸声材料如何采用AML方法进行计算隔声量呢？
一样的，比如你从左到右依次为声学有限元网格（外表面为AML属性）、第一层结构网格（一侧与中间空气层耦合）、中间空气层（两侧与两侧结构网格耦合）、第二层结构（一侧与中间空气层耦合）、声学有限元网格（外表面为AML）属性。
应该就是这样，应该就是多设置几个耦合面而已。 声学有限元计算隔声量，不管是墙还是空气，都是要建声学有限元网格的。建议楼主发模型上来看看。 superxjw 发表于 2013-3-1 12:36 static/image/common/back.gif
一样的，比如你从左到右依次为声学有限元网格（外表面为AML属性）、第一层结构网格（一侧与中间空气层耦合 ...
主任，我做的是在有机玻璃上面粘结一层橡胶材料，那么该怎么建立模型，建立两个结构模型吗？两者之间怎么定义粘结关系？网格怎么划分？怎么分别定义材料属性呢？ 土豆丝 发表于 2013-5-16 19:50 static/image/common/back.gif
主任，我做的是在有机玻璃上面粘结一层橡胶材料，那么该怎么建立模型，建立两个结构模型吗？两者之间怎么 ...
按照道理，粘上去的东西，不能按照刚性连接来处理的，但是我个人觉得，如果你要简单一点，就做成一个整体网格，不同部分定义不同的属性就行。这个在VL声学有限元的帮助算例，直接声振耦合计算汽车挡风玻璃隔声量（中间是玻璃，两侧的两层是PVB）里面都有详细操作呀，看看那个算例就会了。 superxjw 发表于 2013-5-16 20:17 static/image/common/back.gif
按照道理，粘上去的东西，不能按照刚性连接来处理的，但是我个人觉得，如果你要简单一点，就做成一个整体 ...
我没有帮助文档，能不能详细说一下操作步骤呢，急急急！ 本帖最后由 superxjw 于 2013-5-16 20:37 编辑
帮助文档就在本版置顶的地方，你去下载了看一下吧，学这些东西，肯定是要习惯看帮助文档的。。。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 Loss The model contains a Visco-elastic frequency-dependent material.
Tutorial Data Files:StructuralGroups.xmlSAFyoung.xlsLaminatedStructure.bdfFPmesh.bdfAMLsender.bdfAMLreceiver.bdfAcousticGroups.xmlSTEP BY STEP Tutorial:STEP 1 After starting LMS Virtual.Lab, create a new document in the Acoustic Harmonic FEM Workbench (Start file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Acoustics file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Acoustic Harmonic FEM).STEP 2Select File file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Import from the main menu. A file selector window appears allowing you to specify the file type and the file name. Importing Data]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. file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63446.gifSTEP 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 file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Materials file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif New Materials file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif New Viscoelastic Material...Materials feature in the Specification Tree file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif New Materials file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif New Viscoelastic Material]Define the materials as follows:
GLASSPVB
Young ModulusConstantPoisson RatioMass DensityYoung ModulusPoisson RatioMass Density
RealImaginary0.232500 kg_m3Frequency Dependent0.491066 kg_m3
7.15e+011 N_m21.401e+009 N_m2
file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63448.pngThe 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.file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63449.pngIn 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.file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63450.pngSwitch the Data Format to Linear Amplitude/Phase (deg) because the file contains the values like that. Click the Import button.file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63451.gifClick 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:file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63453.gifSTEP 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 file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Properties file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif New Structural Properties file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Create 3D-PropertyProperties feature in the Specification Treefile:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif New Structural Properties file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Create 3D-Property]file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63454.pngfile:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63455.pngfile:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63456.pngBefore the following steps please make sure the Mesh Parts are defined as types:PROPERTY0 – StructuralGlass – StructuralPVB – StructuralThis can be done by going to Tools file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Set Mesh Parts TypeSet Mesh Part Type file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif 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 file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Import Acoustic Mesh file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Model Mesh..., and select the file AMLreceiver.bdfUse Meter, Kilogram and Seconds units, and include the materials and properties.Similarly, import AMLsender.bdf. file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63457.pngfile:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63458.gifAt this point the mesh parts type definition window should look like this: file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63459.gifSTEP 6 Inserting the New Material and properties for the new imported meshesInsert a new Acoustic material as follows (use the default values for air):file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63460.gifInsert 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).file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63461.pngSTEP 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 file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Mesh Grouping file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif 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.file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63462.pngRight-click the Group Set, and use Mesh Grouping file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Group Selection Dialog…:file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63463.gifSimilarly 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 file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Group Selection Dialog…:file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63464.gifStep 8Save the analysis, but without closing.
SETTING UP THE ACOUSTIC CASESStep 1Insert a new acoustic automatically matched layer property to take into account the semi-infinite extent of the sender and receiver rooms. Insert a new AML property by right-clicking Properties, use New Acoustic Properties file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Automatically Matched Layer Property....file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63465.pngApply it to the two Acoustic groups AML Receiver and AML Sender. Switch the Radiation surface to User Defined, and select the AML Receiver group.file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63466.gifStep 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: file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63467.pngTo perform this calculation use No Load function Set and No Load Vector Set.Create new sets for all the rest.file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63468.gifSTEP 3Expand the Direct Vibro-Acoustic Response Analysis Case from the Specification Tree, right-click the Boundary Condition Set and use Acoustic Sources file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Distributed Plane Waves... with a Refinement Level of 2, a Radius of 4m, 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.file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63469.gifClick the OK button to generate a set of 12 spatially distributed plane waves. By now the model should look similar to this:file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63470.pngStep 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.file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63471.gifStep 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. file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/65044.pngDo the same for the Receiver Side in the end you should have two Coupling surfaces: file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/65045.gifStep 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 1.122462048. Click the OK button to add the frequency range definition.file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63474.pngRequest 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.file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63475.gifStep 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.file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/26000.gif 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).file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63476.giffile:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63477.gifYou 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. file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/50556.gif button from the toolbar and select the Solution Set feature. A third possibility is to use the menu Insert file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif 2D/3D Images file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif 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 button As 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. file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63478.gifSwitch 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. file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/63480.gifSave 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 file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif Other Analysis Cases file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/25979.gif 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:file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/65296.pngUpdate 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:file:///D:/Program%20Files/LMS/LMS%20Virtual.Lab%20OLH%2011-SL2/OnLineHelp/English/online/aco-tut/65298.gif
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