×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

where lies the shell?

where lies the shell?

where lies the shell?

(OP)
hi to everybody.

This is my first post.
Question: a cylinder, 5in inner diameter, 0.1in thick.
I want to mesh it with a shell.
How should I model the cylinder?
A cylindrical surface 5in diameter, or a cylindrical surface
5+2*0.1= 5.2in diameter?
How chooses the program in which direction grows the thicknes of the shell?

Thanks!

edu

RE: where lies the shell?

Model the "mid-surface" of the cylinder i.e. the diameter of the cylinder will be (5 + 0.1) inches. Once you specify the thickness of the shell (0.1 inches) you will be modelling the exact dimensions of your cylinder.


------------
See FAQ569-1083 for details on how to make best use of Eng-Tips.com

RE: where lies the shell?

(OP)
I still have doubts.
For example in the VM6 problem of the Verification Manual, there is cylinder with rext=4.953 and t=0.094,  and the problem wasn't solved taking into account a radius r-t/2.
Is this because the value of the thickness is too small?

Thanks Drej!

RE: where lies the shell?

In cases such as this, I think that Drej and I would agree that you should be doing some hand-calcs first in order to satisfy your "doubts".  In your particular case, I would suggest that you run both the "thin-shell" equations a la "Timoshenko" and the "Lame" equations are well.  Then, once you have satisfied yourself with the hand calc (and only then) should you attempt to run your FE calcs.

RE: where lies the shell?

Forget that problem and deal with the real world. VM6 doesn't explicitly state that the radius "r" is to the outer, centre or inner radius of the cylinder. It's just not clear from the notes. I've done this many, many, many, many times before using the mid-surface of the geometry but, as mentioned, do a test FE model on a simple closed form cylinder problem (see Roark for example problems on closed form solutions, or google it) to satisfy yourself.


------------
See FAQ569-1083 for details on how to make best use of Eng-Tips.com

RE: where lies the shell?

Hi all

You always need to make hand-calcs so you know in what direction your result ought to be. Also you will need it for your report.
Always give an explination why Ansys gives a certain result solution. And yes thats the difficult part.

H.Adams

Garry

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources