SEA Ribbon

The ribbon allows you to quickly access tools and standard functions, and is located along the top of NVH. Click on an icon to open the related tool. Hovering over a group of icons may reveal additional tools.



Figure 1. SEA ribbon

Tools on the ribbon are grouped logically and organized by tabs, which appear along the top of the ribbon. When you click on any of the tabs, the set of tools on the ribbon change to reflect the working context.

The following tools are part of the SEA ribbon.

SEA Subsystem

From the Module Browser, click on a subsystem to manage it.


Figure 2. Create Seasubsystems
Name
Enter a unique name.
ID
Enter a unique ID.
Config
Element type.
Property
Use this field to assign a property model to the element. A property model may be chosen from the Property drop-down menu. The element materials and cross-sectional parameters defined in the selected Property record are displayed. Property records can be used to simplify the model definition in cases where many elements have the same properties. Use Property to define additional property models.
Damping
Specify the damping to the particular subsystem.
Use this field to assign a damping model to the element. A damping model may be chosen from the Damping drop-down menu. This list contains all predefined models that apply to the current element type. Use the damping option/icon to define additional damping models.
Geometry
Based on the element type, update the geometry parameters.
Subsystem Options
Experienced users can change the default choices for the SEA Subsystems for all element types. For certain structural element types, you can adjust the default bending stiffness or conductance of the element and add non-structural mass, component mass, or fluid loading to the element. When the options have been changed, the changes are indicated on the subsystem entity form in the SEA Subsystems field.

SEA Junction

A SEA junction is an energy flow path between two or more SEA subsystems corresponding to a single degree of freedom.


Figure 3. Create Seamjunctions
Junction
A SEA junction is an energy flow path between two or more SEA subsystems corresponding to a single degree of freedom.
Connection
Defines how model elements are connected. Connections provide paths for vibration and acoustic power flow between elements and establish degrees-of-freedom at the element interfaces. A single connection contains one or more SEA junctions.
Name
Enter a unique name.
ID
Enter a unique ID.
Connection type
A predefined type which describes the general form of the connection. The connection type is chosen from the Config drop-down menu.
There are three types of connections in SEAM:
  • Structural
  • Acoustic
  • Structural-Acoustic
Geometry
Choose the type of structural connection and specify its dimension.
Note: Geometry type changes based on the connection type specified.
Template
A variety of connection templates are available. Template details (highlighted) are available.
Note: Template type changes based on the connection type specified.
Under Template, specify the connection elements (the list is dependent on the connection type).
Contact Stiffness
Model element contact stiffness (or element contact stiffness per unit length for line junctions) due to isolation systems. Stiffness values for various degrees of freedom are entered. A blank or zero stiffness indicates no isolation is present for the DOF. Multiple elements in a connection may be isolated. Frequency-dependent stiffness may be defined using a function.
The stiffness DOF's are listed in the isolated element's local coordinate system (x,y,z) rather than the global connection coordinates (X,Y,Z). The z axis is perpendicular to the element surface.
Mass per unit length
Translational and/or rotational masses at a junction (or mass/length for line junctions) are specified in this section. A junction mass changes the junction impedance, which may reduce or otherwise change the coupling between the elements in the connection. A translational mass changes the junction impedance for all translational degrees of freedom and a rotational mass changes the junction impedance for all rotational degrees of freedom. Frequency-dependent masses may be defined using a function.
Constrained DOFs
Structural junctions typically involve translation and rotation through several degrees of freedom (DOF). This option allows you to block energy transmission through any DOF by constraining its motion. Physically, constraining a DOF in SEA means that the elements are free to move (translate or rotate) without causing a reaction or transmitting energy to other elements in the connection. This is opposite of the definition of a constrained DOF in an FEA model, where the elements at the DOF are rigidly constrained to have no relative motion.
Cross Coupling
Cross coupling junctions connect the bending and in-plane subsystems within the same structure. This coupling is observed for real-world structures, even when the junction appears symmetric.

SEA Excitation

An excitation is generated from an input load. An excitation acts on an SEA subsystem or junction, whereas an input load acts on a Altair SEAM element or connection.

SEAM calculates subsystem power inputs at each frequency band based on the Input Load specifications.


Figure 4. Create Seamexcitations
Name
Enter a unique name.
ID
Enter a unique ID.
Input Load
Power input to the model from vibration and acoustic sources.
Config type
A predefined type which describes the general form of the Input Load. The Input Load type is chosen from the Config drop-down menu.
Note: The Input Load type determines the Input Load parameters, so the Input button remains inactive until an Input Load type is selected.
Power Input
The power into an element is directly specified. Use the Power Input type when simple power transfer functions are desired or when detailed calculations of input power have been performed outside of SEAM. This type is particularly useful when power input has been measured during a test.
Reverberant
The reverberant vibration or sound pressure level is specified directly at an element. SEAM calculates the required input power to achieve the specified response.
Applied Load
This includes point forces, displacements, velocities, or accelerations specified at an element or a connection. Use the Applied Load type to simulate shaker tests or other compact excitation sources. SEAM uses the subsystem impedances to calculate input power for applied loads.
Subsystem
Subsystem on which the load is applied.
Subsystem Type
Subsystem type forces on which the load is applied.

Properties



Figure 5. Create Properties
Name
Enter a unique name.
ID
Enter a unique ID.
Card Image
A predefined type which describes the general form of the element that the property can be applied to. The property type is chosen from the Card Image drop-down menu.
Note: The property type determines the property parameters so the Input button remains inactive until a property type is selected.
Material
Assign material models to the property. The number of materials required depends on the element cross-section. For example, a layered cross-section can contain up to four materials. In these cases, you must enter a material in the first data cell. A material may be chosen from the drop-down menus located in the material field. These lists contain all predefined models which apply to the current property type.
Type
Options based on the Card Image type selected.

Dampings

Damping models are used to associate damping properties with an element. The damping models in SEAM can be used for many complex applications.



Figure 6. Create Dampings
Name
Enter a unique name.
ID
Enter a unique ID.
Damping Type
A predefined type which describes the general form of the damping. The damping type is chosen from the Config drop-down menu.
Note: The damping type determines the damping parameters.
From the Config drop-down menu, select one of two basic damping types. The basic damping types are:
  • Structural - General damping model for a structural element.
  • Acoustic - General damping model for an acoustic element.
Parameters
Use the parameter fields to enter the data for the damping model. The parameter fields that are displayed depend on the damping type selected:
  • Structural Damping parameters
  • Acoustic Damping parameters

Parameters



Figure 7. Create Parameters
Structural Output
Specifies the output reference quantity for structural subsystems. A reference value is required to normalize the output. For example, for global units of IPS, to get the structural response in g’s, select acceleration with a reference value of 386 (in/sec2).
Acoustic Output
Specifies the output reference quantity for acoustic subsystems. A reference value is required to normalize the output.
Energy Output
Specifies the output reference energy quantity for all subsystems. This value is not currently used in SEAM. Set the energy output reference quantity by editing the second entry on Line 12 of the SEAM parameter file.
Power Output
Specifies the output reference power quantity, including modal power, for all subsystems. This value is not currently used in SEAM. Set the power output reference quantity by editing the first entry on Line 12 of the SEAM parameter file.
Variance Options
Specifies the type of variance analysis, if any.
None
Omits the variance analysis.
Analysis Bandwidth
Uses the bandwidth specified in the Frequency Limits field for the variance analysis.
Narrowband
Performs a variance analysis.
Solution Type
Specifies if the analysis is steady-state or transient.
Select transient to activate the Transient Parameters section, where you can indicate:
  • If the system is to start at rest or at steady-state.
  • The total number of time steps.
  • The time steps per second.
SEAM has limited support for transient analysis, however more transient options are available under SEAM.
Output Options
Specifies if the output is in decibels or linear values.
SEAM Unit
Specifies the units the model is represented in.
Transient Parameters
Specifies options for the Transient Solution type.
Output Options
Specifies the format of the output quantities of responses.
Echo Print Input
Specifies the input files to echo in the output file.
Output Characteristics
Specifies the output quantities printed in the output file. If Response output is selected, you can output the response from all elements and subsystems or only selected subsystems by clicking and selecting one or more elements in the model. This is useful if the model has many elements and attention is focused on a smaller subset of elements.
Global Reference
Specifies the reference values required to normalize the output for different kinds of output.

Run

Run the SEAM code to analyze the model after it has been generated. SEAM displays its progress, which may be closed after the run is completed.

Plot

Use the Plot Manager to plot SEAM results. You can plot model results versus a baseline model or overlay plots from different elements or connections within the same model. The plot controls vary depending on the quantity presented. Plot Manager has three sections:
Results
Results contains the list of responses available from solving the loaded model.
These are subsystems characteristics that you can select to study further. Their organizational structure:


Figure 8.
Subsystems
After selecting the result type, select a subsystem.
Plot Section
Used to display results of the analysis in a 2D plot.
The plot section contains the additional options energy flow and table.
Energy Flow
Present the energy flow after running a model for a particular subsystem. The energy flow into a given subsystem is plotted versus the connected subsystem and is displayed in the SEAM Energy Flow Graph window. A positive value represents energy flow into the subsystem, and a negative value represents energy flow out of the subsystem.


Figure 9. Energy Flow
Table View
Provides a spreadsheet view of SEAM results. This view displays the actual numerical values of the calculated quantities.


Figure 10. Table view