When the cohesive zone material defined at a contact interface is completely debonded, the contact behavior at that interface is changed to standard contact (KEYOPT(12) = 0) by default. This default behavior can be changed for certain CZM materials.

For the cohesive zone materials with bilinear material behavior (TBOPT = CBDD, CBDE or BILI on the TB command), you can specify that the cohesive zone interface be “healed” if the surfaces come into contact again after debonding. To activate this option, use the TBFIELD,CYCLE command to define the CZM material as a function of healing cycle number. You can use multiple TBFIELD commands to specify the material properties for any number of healing cycles, but be sure to start with a cycle number of zero.

For example, the following commands specify healing of the CZM interface if the contact surfaces come into contact after they are completely debonded:

TB,CZM,1,,,CBDE                  ! Activate the CBDE bilinear material behavior
TBFIELD,CYCLE,0                  ! Initial CZM definition (before healing)
TBDATA,1,σmax,Gcn,τmax,Gct,η,β     ! CZM properties
TBFIELD,CYCLE,1                  ! CZM definition for first healing cycle
TBDATA,1, ...                    ! CZM properties to be used after first healing

When the contact interface is completely debonded and the surfaces come into contact again, the debonding parameter is set to 0 - effectively healing the CZM. The healing cycle is incremented by one and the appropriate material data is interpolated for this healing cycle.

This healing option is only available when one of the supported cohesive zone materials is used with contact elements. It is not available when a cohesive zone material is used with interface elements.