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Subject: Re: How to mesh --- Please help!
Author: Jan Christian Anker
Date: 1998-12-17 15:24:00

Here are some of the experiences I have made in
modeling cylinders.

1) Before you start modeling, take a look at closed form
solutions, they might give you some very good ideas
about mesh divisions in longitudinal direction.
Given that the cylinder is fixed at one end, a good element
distribution in longitudinal direction might be

1t, 1.6t, 2t, 4t, 8t, 16t, 32t, ... t = wall thickness.

2) If you use SOLID45, a division of one element per 7.5
degrees in circumferential direction might give you
results that are sufficiently accurate. With SOLID95,
use one element per 12.5 degrees.

3) If you have load concentrations, abrupt thickness changes,
or changes in material properties, use fine element meshes
near these "disturbances".

4) One SOLID45 through the shell thickness is usually enough
in my experience. (If you need to account for plasticity,
you might need significantly more elements through the
thickness).

5) You might want to test statements 1 - 4 above by running
some tests against analytical solutions. (It is easy to do
if you do the model generation as suggested by Steve Owen).

Good luck!

Jan Christian Anker

ANKER - ZEMER Engineering A/S
e-mail: jc.anker@a...
Phone: +47 22 13 95 80 FAX : +47 22 13 95 95
Address: Grindbakken 1, N-0764 OSLO, Norway

> -----Original Message-----
> From: Steve Owen [SMTP:Steve.Owen@a...]
> Sent: Thursday, December 17, 1998 3:10 PM
> To: 'xansys@o...'
> Subject: [xansys] Re: How to mesh --- Please help!

> From: Steve Owen

> It is very unlikely that you will get a satisfactory result with tets on
> this model. If you are using 5.5, try the new sweeping tool and mesh
> with 45s or 95s. You should first map mesh either the inner or outer
> surface of the cylinder using a shell element (63, 93) and use that as
> your source. The target will be the opposite surface. To specify
> number of elements through the thickness do an lesize on one of the
> lines connecting the two surfaces. The default limit for aspect ratio
> is 1:20 before we Ansys will give you a warning. If you are comfortable
> with increasing that, you can manually change the aspect ratio limit
> using the SHPP command.

> Steve Owen
> Senior Development Engineer
> ANSYS Inc., Pittsburgh, PA
> http://www.andrew.cmu.edu/user/sowen/

> > -----Original Message-----
> > From: Tham [SMTP:cstham@f...]
> > Sent: Thursday, December 17, 1998 2:29 AM
> > To: xansys@o...
> > Subject: [xansys] How to mesh --- Please help!

> > From: Tham

> > Hi,

> > Im trying to mesh a hollow cylinder , with the outer radius is 203 mm
> > and
> > thickness 7.1 mm, the length of the column is 4010 mm. I managed to
> > model
> > the column using Ansys build-in modelling tools (hollow cylinder), but
> > when
> > I tried to mesh it (after selecting the solid92 element and entering
> > the
> > material properties), it hangs most of the time. Then, I try to set
> > the
> > mesh to coarser (Im using smart meshing tool), and finally Ansys
> > managed to
> > mesh the cylinder but with huge number of elements and nodes! (more
> > than
> > 100,000).

> > So, the question is what should i do to reduce the elemnet size? I
> > tried to
> > set the element size coarser by using the global size but still can't
> > mesh
> > it properly.

> > Thanks in advance.

> > Rgds,
> > Clement Tham

Posts possibly associated with message #78AuthorDateScore
63How to mesh --- Please help!Clement Tham1998/12/17 
64Re: How to mesh --- Please help!Marc Seidel1998/12/17 
66Re: How to mesh --- Please help!David Gross1998/12/17 
67Re: How to mesh --- Please help!Xiao Gong1998/12/17 
68Re: How to mesh --- Please help!Tom Davis1998/12/17 
69Re: How to mesh --- Please help!Steve Owen1998/12/17 
70Re: How to mesh --- Please help!Paris Altidis1998/12/17 
74Re: How to mesh --- Please help!Peter Budgell1998/12/17 
77Re: How to mesh --- Please help!Viktor Doundakov1998/12/17 
78Re: How to mesh --- Please help!Jan Christian Anker1998/12/17 
89Re: How to mesh --- Please help!Dan Bohlen1998/12/18 
93Re: How to mesh --- Please help!Clement Tham1998/12/21