Surface Interaction

Use the Surface Interaction dialog to define the *SURFACE INTERACTION card.

Supported cards:

Mechanical interaction properties

*SURFACE BEHAVIOR
*CONTACT DAMPING
*FRICTION

Thermal interaction properties

*GAP CONDUCTANCE
*GAP HEAT GENERATION
*GAP RADIATION

The Surface Interaction dialog contains the following buttons:

Table 1.
Button	Action
OK	Updates the Engineering Solutions database with the changes and closes the Surface Interaction window.
Apply	Updates the Engineering Solutions database with the changes without closing the Surface Interaction window.
Cancel	Closes the Surface Interaction window without any update.

Surface Interaction: Define Tab

Use the Define tab to select the surface interaction properties.

The available options are: Surface behavior, Contact damping, Friction and Gap Conductance. Once you select an interaction property, its corresponding tab will be activated. You can also define optional parameters (Pad thickness) and data lines (out-of-plane thickness for 2D model or cross-sectional area at every nodes for node based surface). See the Abaqus Online Documentation for a detailed description of these parameters.

In addition, the Gap heat generation value can be defined directly in this dialog, it does not require you to open a new tab, as the other options do. If the Gap heat generation is enabled, the following two values need to be defined:

Dissipated energy fraction - specifies the ratio of how much of the energy in a non thermal contact such as friction is producing heat
Weighting factor - decides how much heat goes in one or the other surface of the contact

By default 50 percent of one value is applied to the other (so the default value is 0.5).

Surface Interaction: Surface Behavior Tab

Use the Surface Behavior tab to create *SURFACE BEHAVIOR cards with optional parameters and corresponding data lines.

The supported optional parameters are: No separation and Pressure overclosure. Options vary according to the selection made in the Pressure overclosure drop down.

Five types of pressure-overclosures are supported:

Table 2.
Pressure overclosure	Description
Hard	In the 2D/3D template, selecting this option provides four new radio buttons: Augmented lagrange, Direct, Penalty, and None. If Penalty is selected, select whether the penalty is linear or nonlinear and enter the corresponding information in the fields that appear. In the Explicit template, there are no data lines needed for this option.
Exponential	There are three fields to define the data line for this option. They are: Clearance at zero contact pressure, Pressure at zero clearance and Direct (for 2D/3D templates only) or maximum stiffness (for explicit only).
Linear	There are two fields to define the data line for this option. They are Direct (for 2D/3D templates only) and Slope of the pressure-overclosure curve.
Tabular	There is a table available for defining the data line values for this option. You need to input the number of data lines required at the Number of data lines entry box. Clicking the corresponding Set button will update the table to have the specified number of rows. For inputting values in the table, click on a cell to make it active and write down the values from keyboard. The table works like a regular spread sheet. You can also read comma delimited data from a text file by clicking Read from file. This button opens a file browser window. Select the file and click Open to export the comma delimited data. The row number is set to the number of data lines found in the file. Note: Right-click in the table to display a pull-down menu containing copy, cut and paste options. Comma delimited data can be copied/cut into or pasted from the clipboard using these options. Hot keys, for example, Control-C, Control-X and Control-V on PC, can also be used. Left-click in a cell to activate the cell. Click in an active cell to move the insertion cursor to the character nearest the mouse. The Shift and Control keys can be used with a left mouse click to select multiple items in a table. Press Control and the left or right arrow key to move the cursor within the active cell. Use the left, right, up and down arrows to change the active cell. Press Backspace to delete the character before the insertion cursor in the active cell. If multiple cells are selected, Backspace deletes all selected cells. Press Delete to delete the character after the insertion cursor in the active cell. If multiple cells are selected, Delete deletes all selected cells. Table columns can be resized by positioning the cursor along a column border, pressing the left or right mouse button, and dragging the border to a new position.
Scale Factor	Modify the default contact stiffness by a scale factors. Available only in the Explicit user profile.

Surface Interaction: Contact Damping Tab

Use the Contact Damping tab to create *CONTACT DAMPING cards with corresponding parameters and data lines.

The supported parameters are: Definition and Tangent fraction (explicit only). The two definition types supported are: Damping coefficient and Critical damping fraction (explicit only). The data item entry options change based on the current template. See the Abaqus Online Documentation for a detailed description of these parameters.

Surface Interaction: Friction Tab

Use the Friction tab to create *FRICTION cards with corresponding parameters and data lines.

The supported friction types (mutually exclusive parameters) are: Default (Coulomb), Elastic slip, Slip tolerance, Lagrange multiplier, and Rough. Depending on the template loaded and friction type selected, the window layout changes to show only the relevant options for defining other parameters and data items. Other supported optional parameters are: Exponential decay, Test data, Anisotropic, Taumax, and Dependencies. See the Abaqus documentation for detailed descriptions of these parameters.

Note: The friction type User is not supported in the Contact Manager. However, it is supported in Engineering Solutionsin the *SURFACE INTERACTION card image.

For all friction types (except Rough), there are four options to define the friction coefficient:

Table 3.
Option	Description
Direct	This is the default method for defining the friction coefficient. Selecting this option means that the Exponential decay and Anisotropic parameters will not be written in the input file. The No of Dependencies checkbox and corresponding entry box should be used to define the Dependencies parameter. There is a table available for defining the corresponding data lines. The available data items are: Friction coefficient, Slip rate, Contact pressure, Average temperature at the contact point, and average field variable values. The column numbers in the table will change based on the setting for No of Dependencies. The row numbers can be defined at the No of data lines entry box. Click Set to update the table to reflect the specified number of rows. To enter values in the table, click on a cell to make it active and write down the values from keyboard. The table works like a regular spread sheet. You can also read comma delimited data from a text file by clicking Read From a File. This button opens a file browser. Select the file and click Open to export the comma delimited data. The row number will be set to the number of data lines found in the file.
Anisotropic	Defines the data lines for the Anisotropic parameter. The No of Dependencies check box and corresponding entry box should be used to define the Dependencies parameter. There is a table available for defining the corresponding data lines. The available data items are: Friction coefficient1 (first slip direction), Friction coefficient2 (second slip direction), Slip rate, Contact pressure, Average temperature at the contact point, and average field variable values. The column numbers in the table will change based on the setting for No of Dependencies. The row numbers can be defined at the No of data lines entry box. Click Set to update the table to reflect the specified number of rows. To enter values in the table, click on a cell to make it active and write down the values from keyboard. The table functions like a regular spread sheet. You can also read comma delimited data from a text file by clicking Read From a File. This button opens a file browser. Select the file and click Open to export the comma delimited data. The row number will be set to the number of data lines found in the file.
Exponential decay	Defines the data lines for the Exponential decay parameter. The available data items are: Static friction coefficient, Kinetic friction coefficient, and decay coefficient
Exponential decay, test data	Defines the data lines for the Exponential decay, test data parameter. The available data items are: Friction coefficient at point 1 (first data line), Friction coefficient at point 2 (second data line), Slip rate at point 2 (second data line) and Kinematic friction coefficient (optional third data line).

When using the Direct and Anisotropic tables:

Right-click in the table to display a pull-down menu containing copy, cut and paste options. Comma delimited data can be copied/cut into or pasted from the clipboard using these options. Hot keys, for example, Control-C, Control-X and Control-V on PC, can also be used.
Left-click in a cell to activate the cell. Click in an active cell to move the insertion cursor to the character nearest the mouse.
The Shift and Control keys can be used with a left mouse click to select multiple items in a table.
Press Control and the left or right arrow key to move the cursor within the active cell. Use the left, right, up and down arrows to change the active cell.
Press Backspace to delete the character before the insertion cursor in the active cell. If multiple cells are selected, Backspace deletes all selected cells.
Press Delete to delete the character after the insertion cursor in the active cell. If multiple cells are selected, Delete deletes all selected cells.
Table columns can be resized by positioning the cursor along a column border, pressing the left or right mouse button, and dragging the border to a new position.

Surface Interaction: Gap Conductance Tab

Use the Gap Conductance tab to define the heat transfer between two surfaces.

Two definitions are possible, both of which can be combined:

Clearance dependant relationship
Pressure dependent relationship

If enabled, the upper part of the dialog writes a *GAP CONDUCTANCE card with the distance versus conductance relationship entered in the table. If you enable the Pressure dependent definition in the lower part of the dialog, the same card with an additional PRESSURE parameter is written out, specifying a pressure versus conductance relationship.

For both tables, additional dependencies can be specified by increasing the number in the No of Dependencies field.

Surface Interaction: Gap Radiation Tab

Use the Gap Radiation tab to define a viewfactor versus distance relationship for heat transfer between surfaces which are very close to each other.

Emissivities for both involved surfaces can be defined. By default, the dialog offers two datalines to define a function of the viewfactor depending on the gap with between two surfaces. The length of the table can be increased by changing the Number of datalines field.