FEM vibro-acoustic workflow

Step	Summary	Detailed help topic
1.	Create a FEM file.	Create a FEM using the Simcenter Nastran****Fem template. Set the Solver to Simcenter Nastran and set the Analysis Type to Vibro-Acoustic.	Create a new FEM file
2.	Define the fluid.	Create the 3D acoustic fluid mesh. In a vibro-acoustic analysis, the fluid and structural meshes can be dissimilar. For each mesh collector, choose the appropriate material and physical properties for your analysis. Note: Your meshing steps will be different depending on whether you are performing an interior or exterior acoustic analysis.	Meshing for FEM acoustic analysisFluid materials for acoustic analyses
3.	Mesh the structural model.	Mesh the structural model or import a structural mesh if desired.For each mesh collector, choose the appropriate material and physical properties for your analysis. Note: Your meshing and defeaturing steps will be different depending on whether you are performing an interior or exterior acoustic analysis.	Meshing for FEM acoustic analysis
4.	Create a Simulation file.	Create a Simulation file using the Simcenter Nastran Vibro-Acoustic simulation template.	Create a new Simulation file
5.	Create an AML (exterior acoustics).	Create an automatically matched layer (AML) to define a reflection-less artificial layer that absorbs outgoing waves regardless of their frequency and angle of incidence.	Create automatically matched layers
6.	Create microphone mesh.	Create a microphone mesh to measure sound inside or outside the fluid.	Create microphones
7.	Create structural or absorbent panels.	Create absorbent panels or acoustic absorber simulation objects on free faces of fluid elements.Or, you can use porous materials to model 3D acoustic absorbers.	Create a panelCreate an acoustic absorberPorous materials
8.	Create structural and acoustic constraints.	You can apply structural constraints only to structural nodes.You can apply acoustic constraints only to fluid nodes.You can add constraints at the solution level or to individual steps.	Create acoustic constraints
9.	Create structural and acoustic loads.	Add acoustic constraints and loads in the simulation file as needed: enforced motion load, enforced acoustic pressure, acoustic nodal force, or acoustic source.You can add loads only at the solution level. You can organize loads within load sets.	Defining acoustic sources and loadsModel and Load Pre-processing solution processUsing fields and expressions to define boundary conditions
10.	Create the solution.	Create a new solution with Solver set to Simcenter Nastran and Analysis Type set to Vibro-Acoustic.Alternatively, you can create a solution directly from a predefined load recipe to apply loads from an external file (for example, containing measurement data) to the simulation model.	Create or modify a solutionCreate a solution from a load recipe
11.	Define forcing frequencies.	Add Forcing Frequencies to solution subcases to excite the model.	Specifying forcing frequencies for a frequency response analysis
12.	Request the types of results to output.	The Vibro-Acoustic Output Requests modeling object specifies the types of results to recover from the solution: acoustic intensity, acoustic power, pressure/displacement, particle velocities, and modal contribution.You can specify output requests both for the solution and for individual solution steps.	Requesting output for Simcenter Nastran analyses
13.	Request modal and panel contribution responses.	You can analyze the contribution of a given mode to the response at a given node and degree of freedom. You can also analyze the contribution of a given vibrating structural panel (the sum of all its nodes) to the pressure response at a given acoustic node.Request responses for the modal and panel contributions by defining the parameters in the respective output requests.	Define modal contribution parametersDefine panel contribution parameters
14.	Define the vibro-acoustic solution parameters.	For vibro-acoustic solutions, in the Solution dialog box on the:Case control page.Create a Fluid-Structure Interaction Control Parameters modeling object, where you can define parameters that control the fluid-structure interaction for the analysis.Specify the Eigenvalue solution method, number of desired modes, and the frequency range of interest.Specify the type of modal damping for fluid and structure (only for SOL 111).Bulk Data page.Create a Fluid-Structure Interface Modeling Parameters modeling object, where you can define parameters that control the fluid-structure interface (coupling) for the analysis.For models with duct modes, anechoic end duct properties, fan noise sources, and surface dipole sources, select the Enable Adaptive Order for Acoustic Elements check box and set the FEM Adaptive Order - FEMAO options.Parameters page.Specify the type of damping for fluid and structure (only for SOL 111)	Define fluid-structure interaction control parametersDefine fluid-structure interface modeling parameters
15.	Solve the solution.	Solve the solution to generate the analysis results.	Solve the model
16.	Post-process results.	Use post-processing tools, such as contour plots or XY graphing, to analyze your results.You can display acoustic nodal pressure results with dB scaling.Nodal results are grouped by response node, type, degree of freedom, and subcase.Verify the quality of any one-way (weak) fluid-structure interface coupling.	Create contour plotsScaling acoustic resultsAnalyzing vibro-acoustic contribution dataPlot vibro-acoustic contribution dataPlot coupling quality results

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