Creating contact initializations

By default, Abaqus adjusts the position of slightly overclosed surfaces in a general contact domain as discussed in Contact Initialization for General Contact in Abaqus/Standard and Contact Initialization for General Contact in Abaqus/Explicit. Contact initializations are used to modify the default behavior for contact surface adjustments. Each contact initialization definition contains a set of adjustment rules; the general contact definition specifies the surfaces to which each initialization definition is applied (see Specifying and modifying contact initialization assignments for general contact).

See Also
Defining general contact
Specifying and modifying contact initialization assignments for general contact
In Other Guides
Contact Initialization for General Contact in Abaqus/Standard
Contact Initialization for General Contact in Abaqus/Explicit

Context:

Contact initializations are intended to correct small gaps or overclosures between surfaces. Specifying large initialization adjustments can lead to mesh distortion and increased computational cost for an analysis.

  1. From the main menu bar, select InteractionContact InitializationCreate.

    The Create Contact Initialization dialog box appears.

  2. Enter a Name for the contact initialization definition, and select a Type for the contact initialization.

    The Edit Contact Initializations dialog box appears.

  3. You can specify the following techniques for treating Initial Overclosures between two surfaces:

    • Select Resolve with strain-free adjustments to adjust certain surfaces to be exactly touching at the beginning of the analysis without creating strain in the model. Only portions of surfaces that lie within the specified distance range are adjusted.

    • Select Treat as interference fits to resolve surface overclosures gradually over the course of the first step in the analysis; this technique creates strain in the model as the surfaces are displaced. Only portions of surfaces that lie within the specified overclosure distance range are adjusted using the interference fit.

      • To establish a uniform overclosure prior to resolving the interference fit, toggle on Specify interference distance, and enter a value for the overclosure distance. Portions of surfaces that lie within the specified distance range (both overclosures and openings) are adjusted to be overclosed by the specified amount. The adjustments occur at the beginning of the analysis without creating strain in the model; the subsequent interference fit resolution during the first step in the analysis will create strain in the model.

    • Select Specify clearance distance to adjust certain surfaces to be separated by a specified value at the beginning of the analysis without creating strain in the model. Only portions of surfaces that lie within the specified distance range are adjusted.

  4. Specify an overclosure distance range; nodes that are overclosed by a value less than the specified distance are adjusted using either strain-free adjustments or a gradual interference fit.

    • Select Analysis default to let Abaqus calculate a maximum overclosure adjustment distance based on the size of the underlying element facets on each surface.

    • Select Specify value to enter a maximum overclosure adjustment distance directly. If you enter a value that is smaller than the calculated analysis default for a surface, Abaqus uses the analysis default value for that surface.

    Warning:

    If two surfaces (or portions of two surfaces) are initially overclosed by a distance greater than the specified adjustment value, contact between these severely overclosed surface regions is not enforced for the duration of the analysis; see Contact Initialization for General Contact in Abaqus/Standard, for more information.

  5. Specify an opening distance range; nodes separated from the opposing surface by a value less than the specified distance are adjusted using strain-free adjustments.

    • Select Analysis default to ignore all open nodes during the initialization adjustments.

    • Select Specify value to enter a maximum opening adjustment distance directly.

  6. Specify other options.

    • Select Adjust nodal coordinates to resolve clearances/overclosures by adjusting the nodal coordinates without creating strain in the model. This option applies only to Abaqus/Explicit analyses and can be used only for clearances/overclosures defined in the first step of an analysis.

    • Select a Secondary node set for clearance to include in the initial clearance specification. The specified clearance is enforced at all secondary nodes in this node set irrespective of whether they are above or below their respective main surfaces. This option applies only to Abaqus/Explicit analyses when the clearance distance is specified. It cannot be used if either overclosure or opening distance is specified.

    • Select the Step fraction for interference value to define the fraction of the step time (between 0.0 and 1.0) in which the interference fit has to be solved. The default value is 1.0. This option applies only to Abaqus/Explicit analyses when the interference distance is specified.

  7. If you want to reset the values in the dialog box to the default values, click Defaults at the bottom of the dialog box.
  8. Click OK to save your contact initialization definition and to close the Edit Contact Initialization dialog box.