SEA Junctions

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



Figure 1. SEA Junctions Ribbon


Figure 2. Create Seam Junction
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).


Figure 3.
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.