Learning Forum

[Mahmoud Mosaad]

Good morning everyone!

I'm studying the effect of delamination on the stiffness of composites and I need to know if there is a way to get the 6x6 stiffness matrix of the composite after adding an interface layer "induced delamination"

thanks in advance!

[Reno Genest]

Hello,

Have you tried with a sampling point? See image below:

 

With a sampling point, you can do a CLT analysis (Classical Laminate Theory) and export the stiffness matrix at the sampling point for the laminate. 

 

Note that the complete stiffness matrix is an 8x8 matrix and includes the shear terms:

 

 

Maybe you are looking for the ABD matrix (6x6) only? You will find more information in th ACP help:

 

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v231/en/acp_ug/Laminate_Matrices.html?q=stiffness%20matrix

 

Let me know if this works for you or not.

 

 

Reno.

[Mahmoud Mosaad]

Hello,

Thanks for your answer but I did try using a sampling point but it gives me the stiffness matrix of the composite without considering the effect of the interface layer that I inserted. 

You can see if you add an ineterface layer, it will not be shown in the modeling ply of the sampling point. 

I hope if you can help me with another solution!! 

Thanks for your time and consideration!

[Reno Genest]

Hello,

Could you create a stackup of the laminate with the interface layer and do the CLT analysis of the stackup instead?

 

Reno.

[Reno Genest]

Hello,

The interface layer should not have any effect on the stiffness matrix. You are not adding any material to the laminate when using an interface layer. If you have plies of prepreg in a laminate, delamination occurs between the plies at the resin. The resin is already there and taken into account in the laminate.

 

Reno.

[Reno Genest]

Hello,

What you want to do is calculate the stiffness matrix before delamination and then after delamination. The before delamination stiffness matrix can be calculated in ACP (Pre). To calculate the after delamination stiffness matrix, first you need to do the delamination simulation in Mechanical (apply loads and BCs) and then use a sampling point in ACP (Post):

 

Let me know if this works for you. If it does not work, then I think you will have to calculate the stiffness matrix manually from the results (displacements) of different load cases in Mechanical. 

 

Let me know how it goes.

 

Reno.

[Mahmoud Mosaad]

Hello, 

At first, thanks for your time!
I tried using a sampling point before at pre- and post- but both give the same results because as I said the interface layer does NOT come up at the sampling point. 
regarding creating a stackup of the laminate with the interface layer and analysing it, I couldn't do that and don't know it it is possible! 
At the end, I think it should be calculated manually!
but at the end thanks a lot for your time and consideration!  

[Reno Genest]

Hello,

The interface layer does not add any material. It does not have any influence on the stiffness matrix and so this is why it is not part of the sampling point. The interface layers allows the simulation of delamination by putting interface elements betweent the solid elements. Without the interface layer, the solid elements are connected at the node and cannot separate.

You want to know the stiffness matrix when some solid elements in a laminate are no longer connected (delaminated). This is not possible in ACP. 

I did not fully understand your question at first.

Yes, I think you will have to perform the delamination simulation in Mechanical and calculate the stiffness matrix manually based on the loads, BCs, and displacements obtained.

 

Have a good day!

 

Reno.