Dependent Variables in Contact Analysis

The and nodes will generate a number of degrees of freedom which depend on the settings and study type. You will see these degrees of freedom appear under in the solver sequence. There are two types of extra variables created:

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Variables changed until convergence is reached during the iterations. These variables appear in the nodes in the solver or in the node.

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Variables used to store the state, once the iterations have converged for a certain time or parameter step. These variables are appear in the node. In a stationary solver, the path to this node is . In a time-dependent solver it appears directly under .


	If you change settings in the Contact or Friction nodes after the solver sequence has been generated, dependent variables may be added or removed. The second case is never a problem, but when new dependent variables are created, they are not automatically added to the groups in the segregated solver. You may then encounter the error message “Segregated solver steps do not involve all components.” You can then either regenerate the solver sequence, or manually insert the missing variables into the Lumped Step and Previous Solution nodes.

In Table 2-8 the dependent variables which can be created by the or nodes are summarized. To shorten the variable names, the full scope has been removed. As an example, the contact pressure variable for pair p1 in component comp1, generated in the Solid Mechanics interface solid, will have the full name comp1.solid.Tn_p1. In the table, it is shown as Tn.

Table 2-8: Dependent variables occurring in contact analysis
vAriable Name	Description	Explanation	created	Solver nodE
Tn	Contact pressure	The contact pressure in the normal direction	Contact: Augmented Lagrangian used	Lumped Step
Tt	Friction force	The friction force vector	Friction: Augmented Lagrangian used	Lumped Step
cm_old	Previous mapped source coordinates	The location on the source where this point was located at last converged solution	Friction node present	Previous Solution
sliptot_old	Previous accumulated slip	Total slip in this point at last converged solution	Friction: Store accumulated slip selected	Previous Solution
contact_old	Contact variable in previous step	Non-zero if the point was in contact at last converged solution within the friction detection tolerance	Friction node present	Previous Solution
isContact_old	Contact status variable in previous step	Non-zero if the point was in contact at last converged solution	Contact: Add contact status to solver log selected	Previous Solution
isSliding_old	Sliding friction status variable previous step	Non-zero if the point was in a sliding state at last converged solution	Contact: Add contact status to solver log selected. Friction node present.	Previous Solution
isSticking_old	Sticking friction status variable previous step	Non-zero if the point was in a sticking state at last converged solution	Contact: Add contact status to solver log selected. Friction node present.	Previous Solution
Wcnt	Contact energy density	Elastic energy stored in normal contact by the penalty factor.	Contact: Store energy variables selected.	Segregated step
Wfric	Frictional dissipation energy density	Energy dissipated by friction	Contact: Store energy variables selected. Friction node present.	Segregated step
cma_old	Previous adhesive mapped source coordinates	Position on the source where this point was located when adhesion was detected.	Adhesion node present	Previous Solution
u_max_old	Maximum adhesion displacement at previous step	Maximum norm of adhesive layer displacement reached until previous step. Also used as indication of adhesion activation.	Adhesion node present	Previous Solution