Modifying the Default Contact Behavior

Automatically detected contacts default to a bonded behavior, but you can modify the properties for the selected contact or contact group in the Tool Options under Group Properties. You can specify how the contacts are grouped, specify a different contact behavior, and specify linear and non-linear properties. These changes apply to all contact pairs in the current contact group. Individually selecting contact pairs applies only to conversion options.

Note: These options apply only to the Default Bonded Contacts group. Once a group is converted to a permanently bonded group or a sliding contact, additional options are available. For more information on these, see Defining Contacts and Contact Tool Guides and Options.

For Detection distance, specify the Min and Max radius of contact detection that Discovery will use to obtain a good convergence during solve.
To modify the grouping behavior, select an option under Contact Face Grouping:
- Select Group faces by body to generate the contact based on grouped bodies.
- Select Group tangent faces to generate the contact based on grouped topologies, such as groups of tangent faces.
- Select No grouping to generate the contact on all separate faces.
For a structural-thermal simulation, select Specify thermal conductance to specify a value for the conductive heat transfer between contact surfaces (the thermal contact conductance). You can specify the thermal conductance as a value, or you can specify a material and material thickness, which Discovery then uses to compute the thermal conductance (material conductivity/thickness). If thermal conductance is not switched on, heat is transferred between the two faces as if there was perfect conduction.

If contact occurs, a small value of thermal contact conductance yields a measured amount of imperfect contact and a temperature discontinuity across the interface. A small thermal contact conductance can also be used to represent a thin layer of material with a different conductivity, such as a gasket.

For large values of thermal contact conductance, the resulting temperature discontinuity tends to vanish and perfect thermal contact is approached.

Note: While Discovery can solve with a value of 0, which specifies no heat transfer between the faces, a project with a 0 value for thermal conductance is invalid when exported to Workbench. You must then replace zero conductance with some small value.

CAUTION: When a contact is excluded or removed due to the suppression of a body, then the thermal conductance is not retained if the action is undone.