importGeometry pde not closed volume H I Beam Partial Differential Equation Toolbox

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Hello everyone. I'd appreciate if you can give me a hand.
I'm creating a H beam STL file in matlab and trying to load it in pde tool but it says:
Error using pde.DiscreteGeometry
Failed to create geometry, the input does not form a closed volume.
This may be due to missing faces or gaps in the input.
The thing is that the stl file is for sure okay. I check the geometry with two different software (3d builder from windows) and AutodeskSimstudio Tools 2016 R3. Both shows a closed volume mesh (empty of course). Even Simstudio can create a full volume (not empty) thanks to the fact that the mesh is closed.
I attach some pictures of the STL and the STL itself (.zip).
Inside view:
Outside view:
View from Autodesk (to take a look of the triangles) :
The code I used here (I attach the other two functions to run it):
clc
clear all
close all
a1=2;
b1=1;
c1=2;
d1=0.5;
k=20;
a2=2;
b2=1;
c2=2;
d2=0.5;
nodes = [...
-a1/2 0 0; ...
-a1/2 0 b1; ...
-d1/2 0 b1; ...
-d1/2 0 b1+c1; ...
-a1/2 0 b1+c1; ...
-a1/2 0 b1+b1+c1; ...
a1/2 0 b1+b1+c1; ...
a1/2 0 b1+c1; ...
d1/2 0 b1+c1; ...
d1/2 0 b1; ...
a1/2 0 b1; ...
a1/2 0 0; ...
a2/2 k 0+(b1+c1/2-c2/2-b2); ...
a2/2 k b2+(b1+c1/2-c2/2-b2); ...
d2/2 k b2+(b1+c1/2-c2/2-b2); ...
d2/2 k b2+c2+(b1+c1/2-c2/2-b2); ...
a2/2 k b2+c2+(b1+c1/2-c2/2-b2); ...
a2/2 k b2+c2+b2+(b1+c1/2-c2/2-b2); ...
-a2/2 k b2+c2+b2+(b1+c1/2-c2/2-b2); ...
-a2/2 k b2+c2+(b1+c1/2-c2/2-b2); ...
-d2/2 k b2+c2+(b1+c1/2-c2/2-b2); ...
-d2/2 k b2+(b1+c1/2-c2/2-b2); ...
-a2/2 k b2+(b1+c1/2-c2/2-b2); ...
-a2/2 k 0+(b1+c1/2-c2/2-b2) ];
%edges = [1 2;2 3;3 4;4 5;5 6;6 7;7 8;8 9;9 10;10 11;11 12];
% faces are oriented such that normals point outwards
f1 = [1 12 11 2; 3 10 9 4; 5 8 7 6]; %root face
f2 = f1+12; %tip face
f3 = [12 13 14 11; 10 11 14 15; 9 10 15 16; 8 9 16 17; 7 8 17 18; 6 7 18 19; 5 6 19 20; 4 5 20 21; 3 4 21 22; 2 3 22 23 ; 1 2 23 24 ; 12 1 24 13];
faces = [f1;f2;f3];
tri = triangulateFaces(faces);
fv.faces = tri;
fv.vertices = nodes;
stlwrite('Hbeam.stl',fv);
smodel = createpde('structural','static-solid');
importGeometry(smodel, 'Hbeam.stl');
Thank you!

Accepted Answer

Cris LaPierre
Cris LaPierre on 17 Jan 2022
Edited: Cris LaPierre on 17 Jan 2022
A quick check with an STL checker (Materialize MiniMagics) found 16 bad edges, which prevents the STL from being 3D printed (what the software is for). It is likely the same issue that is resulting in the warning you are seeing.
When I repair the stl (using an online tool, fixed stl is attached), it imports without error.
unzip('Hbeam_fixed.zip')
smodel = createpde('structural','static-solid');
gm = importGeometry(smodel, 'Hbeam_fixed.stl');
pdegplot(gm)
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