×
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

Shell vs. CBend vs. CBar

Shell vs. CBend vs. CBar

Shell vs. CBend vs. CBar

(OP)
I'm trying to model a bend of rectangular hollow-section tube. Typically, I have used Cbars to model and output the elforce and then apply various factors (stress concentration due to bend; extra shear from torsion etc.) to calculate the "applied stress" on the tube.

As a simple test case, I have setup a 90deg bend test case, separately, with CBend and CBar elements. CQuad model is used as a benchmark.

The bent tube is being pulled apart by a load. However, the stiffness of the 1D elements is almost double of the shell's. Also, CBar and CBend results are practically identical.

1. Is this the limitation of 1D vs 2D elements?

2. What would be the better approach in modelling thin-walled rectangular tubes with bend, on assembly-level model without using CQuads?

3. Would the bend stress concentration and torsional shear have been modelled within the 1D elements already?


Thank you all.

RE: Shell vs. CBend vs. CBar

It would make sense to me that the smaller your wall thickness to diameter ratio is the worse your results are going to be.  1D elements would not account for walls warping and changing shape under load.  Like how with 1D beam theory as a guide I could design a pretty stiff column with just aluminum foil.  Just my 2 cents.

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