# Connector friction behavior

 Frictional effects can be defined in any connector with available components of relative motion. A typical connector might have several pieces that are in relative motion and are contacting with friction. Therefore, both frictional forces and frictional moments may develop in the connector available components of relative motion. To define connector friction in Abaqus, you must specify the following: the friction law as governed by a friction coefficient; the contributions to the friction-generating connector contact forces or moments; and the local tangent direction in which the friction forces/moments act. The friction coefficient can be expressed in a general form in terms of slip rate, contact force, temperature, and field variables; defined by a static and kinetic term with a smooth transition zone defined by an exponential curve; and limited by a tangential maximum force, $Fm⁢a⁢x$, which is the maximum value of tangential force that can be carried by the connector before sliding occurs. Abaqus provides two alternatives for specifying the other aspects of friction interactions in connectors: Predefined friction interactions for which you need to specify a set of parameters that are characteristic of the connection type for which friction is modeled. Abaqus automatically defines the contact force contributions and the local tangent directions in which friction occurs. Predefined friction interactions represent common cases and are available for many connection types (see Connection types). If desired, known internal contact forces (such as from a press-fit assembly) can be defined as well. User-defined friction interactions for which you define all friction-generating contact force contributions and the local tangent directions along which friction occurs. The user-defined friction interactions can be used if predefined friction is not available for the connection type of interest or if the predefined friction interaction does not adequately describe the mechanism being analyzed. Although more complicated to utilize, user-defined interactions: are very general in nature due to flexibility in defining arbitrary sliding directions via connector potentials and contact forces via connector derived components; allow for the specification of sliding directions, contact forces, and additional internal contact forces as functions of connector relative position or motion, temperature, and field variables (the internal contact forces can also be dependent on accumulated slip); and allow for several friction definitions to be used in the same connection applied in different components of relative motion. The following topics are discussed:
 Related Topics About connectors Connector behavior Connector functions for coupled behavior In Other Guides *CHANGE FRICTION *CONNECTOR BEHAVIOR *CONNECTOR DERIVED COMPONENT *CONNECTOR FRICTION *CONNECTOR POTENTIAL *FRICTION Defining friction

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