×
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

Abaqus Explicit. Ignored Boundary Condition

Abaqus Explicit. Ignored Boundary Condition

Abaqus Explicit. Ignored Boundary Condition

(OP)
Dear All,

First of all, thank you for reading this. I am new to Abaqus and especially Abaqus Explicit but have a lot of experience with FEM, implicit and explicit.
I am investigating using Abaqus explicit for the following application and I am running into a singular error.

I have two hexagonal ducts with non constant cross-section. Please refer to the attached file. One duct is pinned at the base (throught a reference point) and also constrained from X-Y translations in a region near the center (as shown in the first picture).
The second duct is not constrained at one end and is being pulled with a smooth prescribed displacement at the other end.
The ducts are specified a Surface to Surface contact with friction and linear pressure-Overclosure normal behavior with a contact stiffness of 1000 (N/mm).

No problem running this with Abaqus Implicit. I am investigating using Abaqus Explicit (I made of the necessary changes, like element types, step, etc..) but results are mind-boggling.

Abaqus Explicit results: the duct with prescribed pulling simply rolls away from the constrained ducts as shown in the attached file.

Can anybody with experience with Abaqus explicit give advices / opinions?

Thank you for your time!

-Francesco

RE: Abaqus Explicit. Ignored Boundary Condition

"The second duct is not constrained at one end and is being pulled with a smooth prescribed displacement at the other end."

Not constrained?

RE: Abaqus Explicit. Ignored Boundary Condition

(OP)
Hello Mustaine3,

the duct being pulled (the front duct in the images on the attached file) is not constrained at the base (the right end side). The only BC is therefore the prescribed displacement.

This model obviously doesn't seems very useful as it. I am building it step by step, so once I get it to work with two components, I'll add more.

Would you have any idea of why when running it explicitly (rather than standard) it ignores the applied displacement and rather rolls away from the static duct? I am thinking it has something to do with the contact algorithm.

Thanks again for your time.

RE: Abaqus Explicit. Ignored Boundary Condition

Then remove your current contact definition and use the general contact with the default settings and the default contact behavior. Usually they work pretty good.
Your linear pressure-overclosure curve is unusual and could be the problem.

If that's not helping, zip and attach your .inp.

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