Tutorial Exercise on Ansys ACP PrepPost

The following notes will be taken from the tutorial provided by Ansys below:

 

This tutorial goes over a simple analysis with regards to ACP Pre and Post. It adds a couple of things that we are currently missing with regards to our own method of approach with evaluating composites. Primarily sampling points and failure criteria. These two are quite interesting and may prove useful.

 

*Please note that although the tutorial asks to open the archived tutorial, I don’t have access to it and made my own 200mm x 200mm sample*

 

ACP Pre

They start off by creating their own material, they don’t use any of the built-in ansys materials. They created their own UD Carbon Fiber and their own Core.

The way this is done is by the following:

  1. Go to engineering data

  2. Where it says “click here to add material” Name your materials, the names they used were “UD_T700” and “Corecell_A550”

  3. You then add the various properties you’d like to define such as “orthotropic elasticity” and “orthotropic stress limits” by double-clicking, below are the ones used for the carbon fibre (circled in red),

  4. You then add your values of these various constants in the boxes shown below (I believe for accurate composite simulation we should add AX-5201XL as our material that we use if it isn't the generic woven prepreg ansys gives).

  5. This example was done for the carbon fibre, to see what they did for the core refer to the tutorial as the process is the same, just gives different values.

Model

As always, remember to add your mesh and the various small things done for ACP pre. If you aren’t aware of what to do, consult either

Ansys ACP Simulation Notes

or

FEA Workshop 2.6.2021

 

Setup

Again, if you don’t know what to do, consult one of the two resources above although there are a couple differences the tutorial did, I will explain those below.

 

  1. They create a laminate of two +45/-45

  2. They then make a sublaminate

  3. The final difference is the way they make their stack up, it goes sublaminate, core, then three layers of 90-degree UD carbon fibre. Your modelling groups should then look like this:

 

Then, connect Setup in ACP Pre to Model in Static Structural,

 

Static Structural

This section is quite simple, all it is is adding a fixed support and a downwards pressure as shown in the figure below:

 

Figure 1: Downward pressure of 0.1 MPa and fixed supports on the 4 edges.

 

ACP Post:

This is where the real fun begins, I found out a lot of new things in this section.

 

Failure criteria

Before this, I didn’t really touch failure criteria but found some really cool things about it.

The failure criteria being evaluated were Max Stress, Tsai-Wu, Face Sheet Wrinkling, and Core Failure.

The way these are added is by the following:

  1. Go to definitions

  2. Right-click definitions, and click “Create Failure Criteria:

  3. Finally, check off any failures you’d like to see.

 

Sadly, the geometry I used wasn’t adequate, I believe it was too small compared to what they used in the tutorial, when I got this:

 

They got this:

Taking away cf (core failure) I get something like this

 

If I remember correctly, the value obtained from each element will not result in failure unless it is over one, in other words…when the element is orangey-red or red like in my first picture where they were all cf. This is because all of these failures are irf and when irf > 1, it denotes failure.

 

Sampling points

These are rather simple, you just create a sampling point and inside the sampling points properties, click on point, then click on your specimen to sample at that point.

 

You can then go into the analysis tab and after configuring a couple things like this:

As you can see, a graph pops up, this one in particular isn’t mine, this is:

If I’m interpreting the values correctly, this graph shows the values of stress (most likely in MPa?) within every single part of the sandwich construction, as you can see the very bottom of the panel would have a stress of -10 MPa in the 1 direction with a stress of around -1.25 MPa at the very top of the panel in the 1 direction. You can also do this for so many directions along with strains and failures, below is what each of the abbreviations means:

In my example, I evaluated s1, s12, and s2

 

Below is a graph of failures :

As you can see, this graph is evaluating the reserve factor, anything below 1 discloses failure. the first three layers have a possible failure with maximum stress in the 2 direction with tension? (this is rather confusing) the core has a core failure if I’m not mistaken, it is cut off. then the fifth layer has tsai-wu, etc. (Please correct anything that may be wrong here but I hope that they’re correct)

 

 

Small Conclusion

As you can see, there are a couple of things that we may start implementing into our simulations to give some more insight as to what may happen because as it is, I currently just get the stress and strains, that’s about it but I think that we should start incorporating the above things into ACP post to make more use of it!