Extrusion to Volume Model

SOFiSTiK Teddy
,
1

Hello!

I am trying to compare the response of a shell model with an equivalent 3D solid model in SOFiSTiK 2025, but I obtain a very large difference in displacement and I cannot identify the reason.

Shell model

The shell model is created using one structural area:

SAR 1 T 100 MNO 1

The pressure is applied using

AREA SAR 1 TYPE PZ -100

And the maximum displacement is approximately 54 mm.

Solid model

The solid model is created by meshing the same structural area into QUAD elements and then extruding them:

+PROG SOFIMSHC urs:2
head Geometry

syst spac gdiv -1000 gdir negz

ctrl mesh 2+64
ctrl hmin 0.10
ctrl deln 0

spt 1  0 0 0
spt 2  3 0 0
spt 3  3 0 3
spt 4  0 0 3

spt 5  0 0.1 0

sln 1 1 2 fix ppmm
sln 2 2 3
sln 3 3 4
sln 4 4 1
sln 5 1 5  sdiv -5

sar 1 grp 1 mno 1
sarb out 1,2,3,4

end


+PROG SOFIMSHA urs:3
head Generate BRIC Mesh
syst rest
grp 2
bric prop mno 1
extr type sar 1 path sln 5
echo full
end


+PROG SOFILOAD urs:5
head loads
lc 1 type none
area sar 1 type pz -100.0
lc 2 type none
area sar 1 type px -100.0
lc 3 type none
area sar 1 type py -100.0
end


+PROG ASE urs:6
syst prob line
lc 1,2,3
echo elem full
end

Here, the maximum displacement is only about 5 mm.

Questions

  1. Is EXTR TYPE QUAD GRP ... the correct workflow for generating a solid model from a shell?

  2. Should the original QUAD elements remain active after extrusion?

  3. Can the pressure still be applied with AREA SAR, or should it be applied directly to the generated BRIC boundary faces (GFA)?

Any guidance or example would be greatly appreciated.

Thank you

2

Hi mnkhzaya,

attached a small example file with equivalent displacements.

example_bric.dat (3.2 KB)

Best regards,

Nora

3

Hi Nora!

Thank you for your example!

Here is the model I am working on:

image
image613×754 141 KB

And the TEDDY Script:

+PROG SOFIMSHA urs:3
head Generate BRIC elements
syst rest
grp 2
bric prop mno 1
extr type sar 1 path sln 5 snap topo
end

+PROG SOFILOAD urs:5
head loads

lc 1 type none
area qgrp 1 proj yy  wide 0 type pyp $$
p1 100 0 0 0 $$
p2 100 3 0 0 $$
p3 100 3 0 3 $$
P4 100 0 0 3

lc 2 type none
area qgrp 1 proj xx  wide 0 type pxp 100

lc 3 type none
area qgrp 1 proj zz  wide 0 type pzp -100
end   

+PROG ASE urs:6
syst prob line
lc 1,2,3
grp 1 off
end

Here, the LC1 works because I’m applying the load on the QUAD face elements in the thickness direction, but when I try to apply load from the side (LC2) and the top (LC3), it doesn’t work anymore. I think the reason is because to apply from the side and top, I can no longer use QGRP 1 and instead need the surface area of the BRIC element.

Do you have any idea for applying area load LC2 from the side and LC3 from the top surfaces of BRIC element?

Thank you!

4

Hi mnkhzaya,

applying loads on the QUAD surface should be fine. See attached revised input file:

example_bric2.dat (1.8 KB)

Best regards,

Nora

5

Hi Nora!

Thank you very much! I really appreciate it :slight_smile: