×
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

Axisymmetric Model with Twist

Axisymmetric Model with Twist

Axisymmetric Model with Twist

(OP)
Greetings,

I am attempting an analysis of some experiments in which a hollow tube with non-uniform thickness is loaded proportionally in tension and tosion (such that the nominal axial and shear stresses are proportional).

I am using an axisymmetric analysis with CGAX4 elements. Let me describe my model; see the attached image:

X corresponds to the tube thickness direction, Y is the tube's cylindrical axis, Z is normal (out of the computer screen) (see image).

I link both the top surface (with normal +Y) and bottom surface (normal -Y) to its own reference node and create a kinematic coupling constraint. On the bottom, I fix the reference point.
On the top, I permit no translation in X, Z, and no rotation about X or Z. Then, I apply a concentrated force in Y and a moment about Y to this node.

Of interest is the radial contraction of the OD of the structure as it is loaded. Thus, to calculate each node's radial coordinate, I need its X and Z coordinate. In ODB viewer I see that as the model shears, there is displacement in Z. The initially undeformed 2D structure shears in the Z direction under the action of the applied torque, resulting in this Z displacement. However the Z coordinates of every node at every increment is zero!

Can anyone with experience using CG elements explain? Is the Z-displacement I see in ODB viewer meaningless or artificial? Thank you very much.


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