Description: The following options associated with a general contact interaction can now be defined in Abaqus/CAE:

• Contact stabilization in an Abaqus/Standard interaction

• Specification of “feature edges” in an Abaqus/Standard interaction

• Additional methods for defining feature edges in an Abaqus/Explicit interaction

• Specification of an interference distance as part of a contact initialization in Abaqus/Standard

• Specification of an initial clearance distance as part of a contact initialization in Abaqus/Standard

Contact stabilization introduces viscous damping to oppose incremental relative motion between two surfaces in an Abaqus/Standard general contact interaction. The main purpose of the damping is to stabilize rigid body motion before the surfaces come into contact, at which point contact and frictional forces counteract the motion. A contact stabilization definition is created in Abaqus/CAE using the contact stabilization editor; you provide a name for the stabilization definition and a set of stabilization factors (see Figure 10–6).

General contact includes a supplementary edge-to-surface contact formulation that is activated to improve contact resolution for so-called feature edges. In Abaqus/CAE you can now specify feature edges for Abaqus/Standard interactions based on either a specific feature angle (the angle between the normals of two facets connected to the edge) or the perimeter edges of a shell or surface; you can also request that no feature edges be activated on a particular surface. These three options had been available previously for Abaqus/Explicit interactions. Two new options for specifying feature edges are now available for Abaqus/Explicit interactions only: you can activate all edges in a surface or only explicitly selected edges in a surface definition (see Figure 10–8). The limitation on feature angles has also been removed for both Abaqus/Standard and Abaqus/Explicit interactions; you can now specify any feature angle between 0° and 180°.

Contact initializations in an Abaqus/Standard general contact interaction are used to specify whether initial overclosures should be resolved without generating stresses and strains or treated as interference fits that are gradually resolved over multiple increments. Abaqus/CAE now allows you to specify an initial interference distance as part of an initialization—nodes within the requested search tolerance are repositioned using strain-free adjustments so the surfaces are overclosed by the specified interference distance; the overclosure is resolved as an interference fit when the analysis begins. You can also now specify an initial clearance distance—nodes within the requested search tolerance are repositioned using strain-free adjustments so the surfaces are separated by the specified clearance distance. Figure 10–9 highlights the new options in the contact initialization editor.

Interaction module:
   InteractionContact StabilizationCreate
   Create Interaction: General contact (Standard): Contact Properties: 
      Stabilization assignments: Edit
   Feature edge criteria assignment editor: Select the surface, click the arrows to transfer the surface to 
      the list of feature assignments, and enter PERIMETER, ALL, PICKED, NONE, or an angle value 
      in the Feature Edge Criteria column.
   Contact initialization editor: Treat as interference fits: Specify interference distance
      or Specify clearance distance