I'm needing to perform a modal analysis of a composite plate. For instance a plate may be 8 layers with 0/90/45/90 stacking sequence. Then in between the 4th and 5th layers there is some small region of delamination (teflon tape), where the layers are not bonded. How can I model this in ANSYS? Should I just define the connections such that the region of delamination is not connected? Or perhaps using a CZM interface?
Hi Brandon,
In modal analysis the CZ won't work because it is not an incremental procedure to understand the interactions of the cohesive zone method. If you use modal analysis I suggest to model the delaminated region as NOT connected to the main construction.
If you want to see the real responce of the structure you should perform a force responce analysis and use contact interactions between the two delaminated interfaces.
The CZM is to predict the delamination and NOT to model the already existed delamination.
I hope I helped.
Regards
Dear Brandon,
First of all you should accept the fact that the delamination can be modeled only as an opening between the nodes of the 4th and 5th ply. Then in case you already know the direction of the opening (expansion of the delamination) you can use either VCCT or CZM method depending on the loading modes imposed to the plate (Mode I, Mode II or mixed mode). In any case I agree with Christoforos that you can model only the damage propagation while the initial damage (already existing delamination) can not be modeled using something else than a gap.
Regards,
Antonis Stamopoulos
Thank you all for the responses! I am only interested in the effect the size of the interior delaminated region has on the modes. I will be simulating multiple configurations with varying sizes of delamination! I will most likely just disconnect the delamination from the main construction.
Any idea on how exactly to disconnect nodes in APDL, Modal, or ACPre?
Hi, an efficient way is to create two parts.
The first part will have the thickness from the 1st to the 4th ply while the second from the 5th to the desired number of plies.
The next step should be to divide your parts into sections, see attachment. That is, you should define the delaminated region. Assuming the delaminated region is the 5th section you should define kinematic/displacement constrain interactions between the top face of the first part and the bottom face of your second part in all sections except the delaminated one.
Regards
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