×
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

Contact between plates

Contact between plates

Contact between plates

(OP)
Hello there!

I am conducting a simple simulation where I have placed 2 plates of equal dimension and thickness one upon another. I have pinned one corner and restricted motion in the z direction for the edge faces. I have applied an equal shear load on all the edge faces for both the top and bottom plate and have implemented a contact between the 2 plates. When I run the simulation, I find that the 2 plates don't deform the same, even though the boundary conditions and loading conditions are the same. What could be the reason for this behavior? Could it be due to the contact?

I have attached the inp file below. It takes barely 15-20 seconds to run. Do help in brainstorming!

RE: Contact between plates

Could you also attach a picture of your model ? Did you try with tie constraint between the plates instead of contact ?

RE: Contact between plates

You have a singular system with a possible rigid body motion for each part. So there isn't a unique solution.

RE: Contact between plates

Your model only solves thanks to self-equilibrating load. Otherwise it would fail to converge due to rigid body motion - spinning around the fixed edge. You have to constrain this RBM first.

RE: Contact between plates

(OP)
Hello guys!

I had tried changing the mode of contact implementation. I was using a small sliding formulation with a node to surface discretization. I changed it to a finite sliding formulation and tested it for both node to surface and surface to surface discretization and it worked well!

@FEAway yes I do understand about the self-equilibrating load part of it. I initially tried to use a point load and the solver didnt converge at all. I didn't want to use a tie constraint and intentionally used a contact. I had posted a question last week about my composite plate with a hole rotating, and i was trying to solve a plate without a hole first. Changing the sliding formulation appears to have solved the rotation problem too! If you have any idea as to why that is so do let me know.

@Mustaine3 I am not exactly sure what that means. I will follow up on that if I find any issues in the simulations hereafter.

RE: Contact between plates

You can't solve that problem until you create a statically defined model. So prevent the rigid body motion of your two parts by making sure they cannot rotate free about one axis. Add some more boundary conditions, or springs, or stabilization or run it quasi-static or whatever else would do it.

RE: Contact between plates

Generally it is advised to use default finite sliding contact in the vast majority of analysis cases. Small sliding is only needed in specific situations when we are sure that sliding between contacting surfaces will actually be small. In such cases we may use small sliding assumption to speed up the analysis.

RE: Contact between plates

Before running stress analyses, I personally run a modal analysis to quickly ensure my BCs are specified appropriately. The cost benefit ratio of this strategy is so low that it makes little sense not to do it. Besides, one also gains some insight into the lowest modes that will influence the results heavily.

*********************************************************
Are you new to this forum? If so, please read these FAQs:

http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083

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

White Paper - The Evolving Landscape of Commercial Battery-Powered Trucks
What’s driving the evolving landscape of truck electrification? What are the barriers, motivators and strategies for accelerating the electric transition? What insights and resources are available for today’s design engineers working to achieve industry disruption and evolution? For answers to these and other pertinent questions, read this white paper. Download Now
eBook - Rethink Your PLM
A lot has changed since the 90s. You don't surf the Web using dial-up anymore, so why are you still using a legacy PLM solution that's blocking your ability to innovate? To develop and launch products today, you need a flexible, cloud-based PLM, not a solution that's stuck in the past. 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