Create an Area Junction

An Area junction is created between two subsystems. The junction is created on the surface that joins two subsystems.

  1. From the Model ribbon, SEA Junctions group, click the Area tool.
    Figure 1.


  2. From the secondary ribbon, use Struct-Acoustic when there is a structural subsystem between two cavities.
    Figure 2.


  3. In the Create Seam Junction Entity Editor, define the following options for Struct-Acoustic.
    Figure 3.


    Name
    Enter a unique name.
    ID
    Enter a unique ID.
    Config
    Specify the element type.
    Template Type
    Choose from the one of the following template types:
    Area/LRad(opt)
    Enter the Area of the surface.
    Acoustic
    Select the first acoustic.
    Structure
    Select the subsystem.
    Acoustic
    Select the second acoustic.
    Use User Defined TL
    Select it if required.
    Realized Noise Control Treatment
    Realized Noise Control Treatments are automatically added after solving. Realized NCTs are added only when there are NCTs assigned to SEA structural subsystems (plate and shell) connected to a cavity. These realized NCTs can be visualized both on 2D structural subsystems and SEA junctions.
    Location
    Select the surface.
    Leak Definition
    Select options as necessary.
    Contact b/n Structure and Acoustic
    Acoustic Subsystem > Layer Stiffness - Use Curve > Value
    Select a subsystem and enter a value or select Use Curve.
    Options
    Corrections for small areas > Mass law sound transmission
    By default, mass law sound transmission through structures separating two acoustic spaces is included in the SEAM connection. You can turn off this transmission, for example, to study the relative importance of mass law versus resonant transmission. In general, retain mass law transmission in the model.
    Z Translation > Added Mass PUA - Use Curve > Value
    Specify an added mass per area in the connection. The added mass decreases mass-law transmission though the structure.
    Insertion Loss (Above/Below/mass-law) - Use Curve > Value
    Define an insertion loss for the structural-acoustic coupling as either a constant value or a function versus frequency. Use the insertion loss to include the effects of a panel trim or barriers, which is defined as the difference in transmission loss for the bare structure and the treated structure. The first two options for Insertion Loss address the insertion loss from the structure to the acoustic spaces “above” and “below” the structure in the structural acoustic connection parameter form element boxes, respectively. The third option for Insertion Loss addresses the mass law transmission between the two acoustic spaces in the connection.
  4. From the secondary ribbon, use Acoustic when two subsystems are directly connected.
    Figure 4.


  5. In the Create Seam Junction Entity Editor, define the following options for Acoustic.
    Figure 5.


    Use Acoustic junction when two subsystems are directly connected. Create an enclosed boundary using surfaces and convert into cavities using bounding options.
    Name
    Enter a unique name.
    ID
    Enter a unique ID.
    Config
    Specify the element type.
    Geometry
    Type
    Keep Area as the default type.
    Area
    Enter the area of surface.
    Edge Connections
    Select to create edge connections.
    Top Acoustic Subsystem
    Select the Acoustic Subsystem
    Bottom Acoustic Subsystem
    Select the Acoustic Subsystem
    Location
    Select the surface.
    Options
    For Transmission Loss Type, select Transmission Loss or Transmission Coefficient.
    Transmission Loss or Transmission Coefficient
    Enter a user-defined transmission loss or transmission coefficient in dB or as a transmission coefficient in linear units. The relationship between the transmission loss and the transmission coefficient and the calculation of coupling is described in the SEAM Reference Manual. See Acoustic Coupling with Known Transmission Loss.
    Enter a value or select Use Curve.