# how to find out node coordinates for a simple quad element?

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S Priya 2021 年 8 月 16 日
コメント済み: S Priya 2021 年 8 月 17 日
I want to know how to find out the node co-ordinates for a simple shell element?

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### 採用された回答

Wan Ji 2021 年 8 月 16 日

Hi, friend! It seems you are studying the finite element method.
For fem analysis, two important things for preprocessing are nodes and elements.
Usually nodes are stored in a n-by-d matrix (n is the number of nodes, d is the dimension), for example
nodes = [0,0,0; 1,0,0; 1,1,0; 0,1,0; 0,2,1; 1,2,1];
elements are stored in a m-by-s matrix, in a quad element with 4 nodes, s=4, and m is the number of elements. Elements record the node identity and their arrangement in an element. Here two elements are
elements = [1,2,3,4; 3,4,5,6];
IF YOU want show the two shell elements, then use patch function
patch('vertices', nodes, 'faces', elements, 'facevertexcdata', nodes(:,3),'facecolor','interp')
colormap(jet)
IF you want get the nodes of the second elements, just do
ecoor = nodes(element(2,:),:)
ecoor =
1 1 0
0 1 0
0 2 1
1 2 1
Here 2 represents the second element.

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### その他の回答 (1 件)

Fabio Freschi 2021 年 8 月 16 日
It depends on your data structure: now your qeustion is rather vague.
Assuming that you have the node coordinates in the Nx3 array P and the connectivity matrix in the the Mx4 array T and you want to know the node coordinates of the element idx, you may write
Pelem = P(T(idx,:),:);
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S Priya 2021 年 8 月 17 日
I have only the relations between the x, y and z coordinates for the shell facet (quad) element. what would be the further steps for carrying the fem analysis?

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