Create a Structural Junction

Learn how to create a structural junction.

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


  2. From the guide bar, select Lines or Points to create the appropriate structural connection.
    Figure 2.


  3. Select the geometry to represent the junction and click Apply to create a manual connection.
  4. Use the Create Seam Junction Entity Editor to update the junction's details.
  5. In the Create Seam Junction Entity Editor, verify that Point is selected and define the following options.
    Figure 3. Create Seam Junction - Point


    Name
    Enter a unique name.
    ID
    Enter a unique ID.
    Config
    Specify the element type.
    Geometry
    Based on the element type, update geometry parameters.
    Number
    Enter a number.
    Template
    There are five types of templates for point junctions.
    Parallel
    The parallel template is used to model line or point connections between two parallel structures. The connection is assumed to be in the middle of the subsystem. To model two parallel structures connected at their edges and view this effect on the junction impedances and coupling, select Connect at Edge. If beams, pipes, or frames are used, their axes are assumed to be aligned in the same direction.
    Beams
    Up to six beams or pipes can be connected at a junction. The elements are either in-line or perpendicular. Connections to the middle of a subsystem are modeled by dropping the same element name into two symmetric entry spaces.
    Beam-Plate
    Models a beam or pipe perpendicular to a plate or shell. A connection in the middle of a subsystem is modeled by dropping the same element name into two symmetric entry spaces (A and C, B and D).
    X-Cross
    Models a connection of up to four structures with either in-line or perpendicular connections. The template is mainly intended for plate and shell connections. A connection in the middle of a subsystem is modeled by dropping the same element name into two symmetric entry spaces (A and C, B and D).
    Frame
    Models a frame stiffener (beam, pipe, or plate strip) on a plate or shell. A frame in the middle of the structure is modeled by putting the same plate or shell element in entry spaces G and H.
    MC Escher
    An 'MC Escher' junction models a junction with many SEA subsystems that are connected in a way that is not physically accurate, but are needed to define complicated structures.
    Structure F
    Choose the first subsystem.
    Structure G
    Choose the second subsystem.
    Connect at Edge
    Click on square if the edges are to be connected.
    Location > Points/Lines
    Choose the point/line where the junction must be created.
    Element Contact Stiffness
    Use this option to model element contact stiffness (or element contact stiffness per unit length for line junctions) due to isolation systems. A blank or zero stiffness indicates no isolation is present for the DOF. Multiple elements in a connection may be isolated.
    The stiffness DOFs 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's surface. See Masses and springs in the SEAM Reference Manual for more details. Use the Contact stiffness table to define all stiffnesses.
    Figure 4. Contact stiffness table


    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 DOF
    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.