As the title says, I am trying to code in FEM a plate structure that either has a hole in one of the layers or one of the layers is made of patches of plates, rather than one whole plate. However, while I have a slight idea of how to implement this, I'm really not very sure and I would like some questions answered before I start trudging through my code haphazardly.
From what I understand of FEM, I understand that in order to represent a hole or a patch (which is basically a plate with a hole AROUND it) is to change the connectivity matrix for a given layer. However, I don't quite get how I would go about doing that. For example, if I had a 6x6 element plate structure and one of the layers of that plate was to have a 2x2 element hole in the middle, do I simply remove those elements from my connectivity vector? I just have a feeling that would cause some of my matrix dimensions to not match and throw the whole thing into chaos.
Additionally, what if the location/dimensions of my hole or plate didn't align perfectly with the coordinates of my elements? how do I implement that? Would I have to write a completely new coordinate system for my nodes?
I'm sorry if my questions seem either too obvious or too vague. I just wanted to know if I'm heading in the right direction before investing in any major change to my code. If any of you could point me in the right direction or provide some good practice/sample pieces of code that would be great. I'm learning FEM basically through trial and error.