Dependent Variables in Contact Analysis

The , , , and nodes will generate a number of degrees of freedom depending 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:

•

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

•

Variables used to store the state, once the iterations have converged for a certain time or parameter step. Such state variables are not immediately visible in the solver sequence, but it you select the node under in the solver sequence, you will see them listed as ‘Internal variables’.


	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 node.

In Table 2-11 the dependent variables that can be created by the , and 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 similar to comp1.solid.Tn_p1. In the table, it is shown as Tn.

Table 2-11: 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
cm1_old cm2_old cm3_old	Previous mapped source coordinates	The location on the source where this point was located at last converged solution	Friction node present	Internal state variable
sliptot_old	Previous accumulated slip	Total slip in this point at last converged solution	Friction; Store accumulated slip selected	Internal state variable
contact_old	Contact variable in previous step	Nonzero if the point was in contact at last converged solution within the friction detection tolerance	Friction node present	Internal state variable
isContact_old	Contact status variable in previous step	Nonzero if the point was in contact at last converged solution	Contact: Add contact status to solver log selected	Internal state variable
isSliding_old	Sliding friction status variable previous step	Nonzero if the point was in a sliding state at last converged solution	Contact: Add contact status to solver log selected. Friction node present.	Internal state variable
isSticking_old	Sticking friction status variable previous step	Nonzero if the point was in a sticking state at last converged solution	Contact: Add contact status to solver log selected. Friction node present.	Internal state variable
Wfric	Frictional dissipation energy density	Energy dissipated by friction	Friction present and Compute frictional dissipation energy selected.	Segregated step
activation_old	Adhesion condition at previous step	Nonzero if the adhesion condition was fulfilled at the last converged solution	Adhesion node present	Internal state variable
cma1_old cma2_old cma3_old	Previous adhesive mapped source coordinates	Position on the source where this point was located when adhesion was detected.	Adhesion node present	Internal state variable
um_max_old	Maximum displacement jump at previous step	Maximum norm of displacement jump vector reached until previous step.	Decohesion node present and Displacemet based damage selected	Internal state variable
Ydm_max_old	Maximum damage energy at previous step	Maximum value of the stored undamaged elastic energy at previous step	Decohesion node present and Energy based damage selected	Internal state variable
vdmg_old	Viscous damage at previous step	Value of the viscous damage variable at the previous step	Decohesion node present and Delayed damage selected	Internal state variable
Wdmg_old Wsd_old dmg_old		These variables are related to the computation of the energy dissipated by damage	Decohesion node present and Compute damage dissipation energy selected.	Internal state variables