.. _contact:

#######
Contact
#######

This chapter describes the syntax for defining interactions of contact surfaces. For more detailed information on the computational details of contact, consult [:footcite:`con:ref:hein`, :footcite:`sierraSMTheoryManual`].

Contact is the interaction of bodies when they touch. Contact algorithms ensure that surfaces do not interpenetrate and that the interface behavior is computed based on specified surface physics models.

To specify contact enforcement in a model, the user must:

- Identify all surfaces to be considered for contact. Usually this is the exterior surfaces of element blocks used in the analysis.
- Specify which contact surfaces will interact with each other. This could involve tying surfaces together, allowing surfaces to slide against each other, or allowing part of a surface to slide against other parts of the same surface.

Additional algorithmic options may be included to improve the robustness and accuracy of the contact computations.

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.. toctree::
   :hidden:
   :maxdepth: 1

   contact/constraints
   contact/enforcement
   contact/definition
   contact/surfaces
   contact/friction
   contact/interactions
   contact/periods
   contact/analytic
   contact/algorithm
   contact/specific
   contact/log
   contact/examples
   contact/issues
   contact/rigid
   contact/deprecated
