Learning Forum

[Nekonomimi]

Hello.

I try to simulate delamination analysis for the DCB (double cantilever beam) specimen with CZM (Cohesive zone model).

The DCB specimen has cohesive elements between the two solids, and enforced displacement is on the corner of the upper adherend(please refer to the figure).

This analysis seems to have a good result by checking the reaction force at the displacement point.

Thus, I want to know the crack length propagation or coordinate position of the crack tips changing over time, but I don't have a method to do it.

The model is 2D, analysis setting is mechanical APDL, I used contact elements (CONTA 172 and TARGE169) to model CZM (please refer to the attached text file that I input command).

How can I get the crack propagation overtime on the cohesive elements?

VER1.txt

[John Doyle]

The contact elements do have a debonding parameter (DPARAM) that represents a measure of CZM 'damage'. It is available as a nonsummable miscellaneous result (NMISC).It is a scalar value between zero and 1.Zero=no damage.1= fully debonded. Please refer to Table 172.2: Contact172 Element Output Definitions available in the MAPDL Elements Manual.
At the tip of a cracked simulated with contact CZM, the damage parameter should be a small nonzero fractional value that is growing and will eventually equal 1.000 if it becomes fully debonded.
Perhaps you can extract all these DPARAM values to an element table with the commands below and use this information to assess where the crack tip is during the load history.By extracting these results at multiple time points during the load history, maybe you could use this information to approximate the crack propagation rate.
ESEL,s,ename,,conta172
ETAB,damage,nmisc,33
PRETAB,damage
There are other results, like energy released during debonded (DENERI), that can also be extracted in same way, if that is more helpful.

[Dorin Andoni]

Hello, I am doing another simulation, but it also has a CZM contact debonding in Workbench. I am new to the APDL language and I am confused on how can I get, since I have a mixed mode case, both DENERI and DENERII, and where do I add the commands for it in Workbench.
I would be really thankful if someone could help me with this!