Connectors

You will need connectors if you are working with multiple components in your FE Model.  We have four types of connectors: Tie Constraint, Cyclic Symmetry, Structural Bonded Contact, and Thermal Bonded Contact.

Tie Constraint

A Tie Constraint is a rigid connection that ties two nodes together. Tie constraints make the displacement of the selected nodes equivalent, effectively removing one degree of freedom from the system. 

Choose the Independent nodes and the Dependent nodes using a Boundary Selection block. The Independent boundary looks for the Dependent boundary within a specified tolerance. An error will occur if the tolerance is too low to find the boundary. This error can be fixed by increasing the tolerance or editing the boundary. The Rotation checkbox toggles the option to tie rotational degrees of freedom. You can see an example of this below.

Cyclic Symmetry (Beta)

The Cyclic Symmetry block creates tie constraints between an FE Mesh’s upper and lower boundaries.  To reduce file size and drastically reduce the run time for parts exhibiting cyclic symmetry, a single sector can be used to assume consistent results for all identical segments of the revolved feature.  Currently, the Cyclic Symmetry block only works with parts that do not contact the axis of revolution.

Tip:
Although it is unnecessary, you can create a conformal mesh between the upper and lower boundaries of the sector using the Remesh Surface with Cyclic Symmetry (Beta) block. In some cases, this will yield more accurate results.

Structural Bonded Contact

A Structural Bonded Contact is an elastic connection between the two models that allow relative motion with a defined stiffness. It’s usually used if you have two surfaces glued together with some material that has a vastly different stiffness than the connected surfaces, which allows the connected surfaces to not move entirely in sync but have specific resistance between them. It’s often used to calculate contact failure and to model connected/welded surfaces more accurately, but generally for any connection dictated by a finite stiffness.

The setup of the Structural Bonded Contact is very similar to the setup of a Tie Constraint, but now we define the contact stiffness.

Tip:
We recommend a contact stiffness of 0.5 * (Young’s Modulus of Part 1 + Young’s Modulus of Part 2).  Another method of determining the contact stiffness is k = E * A/d (where A is the contact area and d is the contact layer thickness).

Thermal Bonded Contact

The Thermal Bonded Contact block creates a bonded contact between two FE boundaries, allowing heat flux between the two components. Contact resistance can be defined to account for a thin membrane material at the boundary, such as thermal paste. The contact resistance between two materials is often calculated from experimental tests of contact conductance.