Using Contact Surfaces

The Contact Region

To define contact between two entities, Trelis requires each entity to be defined as a separate contact region. Each region can be made up of multiple 1D or 2D entities.

To create a contact region

  1. On the Command Panel, click on FEA BCs and then Contact Region.
  2. Click on the Create action button.
  3. Specify ID(s)/Name settings.
  4. Select the Contact Region Entity and specify the Entity ID(s). This can also be done using the Pick Widget function.
  5. Click Apply.

Create Contact Region [id] [Name <'name'>] [{Add|On} {Sideset|Surface|Curve|Face|Tri|Edge} <entity_list>]

To modify a contact region

  1. On the Command Panel, click on FEA BCs and then Contact Region.
  2. Click on the Modify action button.
  3. Specify ID(s)/Name and optionally Change Name.
  4. Select Add Entities or Remove Entities.
  5. Select the Contact Region Entity and specify the Entity ID(s). This can also be done using the Pick Widget function.
  6. Click Apply.

Modify Contact Region {id_list|'name'|All} [Name <'name'>] [{Add|Remove} {Sideset|Surface|Curve|Face|Tri|Edge} <entity_list>]

The Contact Pair

To create or modify a contact pair

  1. On the Command Panel, click on FEA BCs and then Contact Pair.
  2. Click on Create or Modify.
  3. Enter the appropriate settings.
  4. Click Apply.

create contact pair [id] [name <'name'>] [master contact region <id|'name'>]  [slave contact region <id|'name'>] [friction <value>] [tolerance <value>]  [tied {on|OFF}] [General <on|OFF> [Exterior <on|OFF>]]

modify contact pair {id_list|'name'|all} [name <'name'>] [master contact region <id|'name'>] [slave contact region <id|'name'>] [friction <value>] [tolerance <value>] [tied {on|OFF}] [General <on|OFF> [Exterior <on|OFF>]]

A contact pair is composed of two contact regions.  One region will be the ‘master’ surface, and the other will be the ‘slave.’  2D contact regions can not be mixed with 1D contact regions.  The friction coefficient can also be included.  The tolerance keyword is currently unused.  Use the tied keyword to specify that the contact is to define tied contact between the two contact regions, essentially “gluing” the parts together.  Currently, this option is only available when using the Abaqus Exporter.

The General keyword can be used to specify general (i.e. global) contact without specifying surfaces/curves to use as contact pairs. Currently, this keyword is only valid when exporting to Abaqus. If the Exterior keyword is used with the General keyword, then Abaqus will consider all exterior surfaces when determining contact regions. If the Exterior keyword is omitted, then the user must provide a master contact region and/or a slave contact region.

 

Auto-Contact Tool

With the auto-contact tool, Trelis can search for contact pairs and automatically set up all of the necessary contact regions and contact pairs.

Create Contact Autoselect [{Volume|Surface|Curve} <ids>] [Master Volume <id>] [Maxgap <value>] [Curve_Contact]

The optional geometry list can be used to limit Cubit’s search to only a subset of entities. If this list is omitted, all bodies in the model will be searched. The optional master volume keyword can be used to tell Trelis which volume should be used as the master contact region. If this keyword is omitted, the user will not have control over which volume is the master region. The maxgap keyword can be used to control how Trelis searches for contact regions. This value is used as the maximum amount of gap that can exist between two surfaces and be identified as a contact region. If this keyword is omitted, the geometry tolerance is used. The curve_contact keyword can be used to indicate the model requires curve contact as opposed to surface contact.