The distance separating
two surfaces is called the clearance. The contact constraint is applied in
Abaqus when
the clearance between two surfaces becomes zero. The contact formulation
imposes no limit on the magnitude of contact pressure that can be transmitted
between the surfaces. The surfaces separate when the contact pressure between
them becomes zero or negative, and the constraint is removed. This behavior,
referred to as “hard” contact, is the default contact behavior in
Abaqus
and is summarized in the contact pressure-clearance relationship shown in
Figure 1.
Figure 1. Contact pressure-clearance relationship for “hard” contact.
By default, “hard” contact is directly enforced when using contact pairs in
Abaqus/Standard.
The dramatic change in contact pressure that occurs when a contact condition
changes from “open” (a positive clearance) to “closed” (clearance equal to
zero) sometimes makes it difficult to complete contact simulations in
Abaqus/Standard;
the same is not true for
Abaqus/Explicit
since iteration is not required for explicit methods. Alternative enforcement
methods (e.g., penalty) are available for contact pairs, as discussed in
Contact Constraint Enforcement Methods in Abaqus/Standard.
Penalty enforcement of the contact constraints is the only option available for
general contact. Other sources of information include
Common Difficulties Associated with Contact Modeling in Abaqus/Standard,
Common Difficulties Associated with Contact Modeling Using Contact Pairs in Abaqus/Explicit,
the “Modeling Contact with
Abaqus/Standard”
lecture notes, and the “Advanced Topics:
Abaqus/Explicit”
lecture notes.
