MERGE_FAILURE_COHESIVE
Contact and tied interfaces
*MERGE_FAILURE_COHESIVE
mfid, $\sigma_{fail}$, $\tau_{fail}$, $G_{I}$, $G_{II}$, $\Delta_{ref}$
mfid, $\sigma_{fail}$, $\tau_{fail}$, $G_{I}$, $G_{II}$, $\Delta_{ref}$
Parameter definition
Variable
Description
mfid
Merge failure command ID
$\sigma_{fail}$
Tensile failure stress
$\tau_{fail}$
Shear failure stress
$G_{I}$
Modus I energy per unit area
$G_{II}$
Modus II energy per unit area
$\Delta_{ref}$
Element reference size
Description
Specifies failure of a merged interface MERGE. Failure is initiated when:
$\left( \frac{\xi \sigma}{\sigma_{fail}} \right)^2 + \left( \frac{\xi \tau}{\tau_{fail}} \right)^2 \geq 1$
where $\xi$ is a scale factor accounting the inability to resolve stress concentrations at coarse element grids:
$\xi = \mathrm{max} (1, \sqrt{\Delta/\Delta_{ref}})$
$\Delta$ is the local characteristic element size on the slave side of the merge interface. The stress unloading from failure is a linear function of the crack opening distance. It is defined such that the consumed energy per unit area of cracking $G$ is:
$G = \sqrt{\left( \frac{\sigma}{\sigma_{fail}} G_I \right)^2 + \left( \frac{\tau}{\tau_{fail}} G_{II} \right)^2}$
