×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

Deactivating TIE in first step, and then activating TIE in second step.

Deactivating TIE in first step, and then activating TIE in second step.

Deactivating TIE in first step, and then activating TIE in second step.

(OP)
Hi everyone.



What I am trying to achieve is pre-tension of some supportive tubes. The reason is that the tubes support a pipe, which is experiencing thermal expansion. To level out the displacement due to heat-transfer, then the tubes are moved a given displacement as a pre-tension.

In first step I want to use *BOUNDARY to give the block below a displacement.
In the second step I want to activate the tie, such that the lower surface (which is the master-surface) is not displaced also.

This is not possible to do with TIED surfaces, as seen below.
Do any of you have any suggestions how to achieve this in some other way or am I missing something?

Step 0 - Pre-Tension of Stays
*STATIC
*MODEL CHANGE, REMOVE, TYPE=CONTACT PAIR
SCR_Stay_Bot_S, SCR_Stay_Bot_M

*BOUNDARY, OP=MOD
MOVE3,1, ,-17.0
MOVE3,2, ,0.0
MOVE3,3, ,0.0
MOVE4,1, ,-17.0
MOVE4,2, ,0.0
MOVE4,3, ,0.0


Step 1 - Pressure
*STATIC
*MODEL CHANGE, ADD, TYPE=CONTACT PAIR
SCR_Stay_Bot_S, SCR_Stay_Bot_M

*BOUNDARY, FIXED
MOVE3,1,3,0.0
MOVE4,1,3,0.0
*DLOAD, OP=NEW
,GRAV,9820,0,0,-1
SCR:press_shell,P,0.386
ScavRec_Press_Shells,P,0.386
Exht_Pressure,P,0.386

***ERROR: CONTACT PAIR (SCR_STAY_BOT_S, SCR_STAY_BOT_M) IS A TIED CONTACT
PAIR. *MODEL CHANGE CANNOT BE USED FOR TIED CONTACT PAIRS

RE: Deactivating TIE in first step, and then activating TIE in second step.

Try with no separation (and rough friction) contact. It will only approximately replace tied contact but should let you achieve desired effect.

RE: Deactivating TIE in first step, and then activating TIE in second step.

(OP)
Hi FEA way, thanks for your reply. I have tried out the matter, that you have described and it seems to be running - but not converging as it is down in incredibly small time steps/increments.

RE: Deactivating TIE in first step, and then activating TIE in second step.

Analyses with contact often exhibit convergence issues. You may have to provide some additional stabilization to your model as rigid body motions might occur. Try enabling automatic stabilization in the step settings. If that doesn’t work there are also special options for contact that increase the chance of convergence. Also reduce initial and maximum increment size and increase maximum number of increments.

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! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close