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2-D Plane stress Neat-fit problem

Hi,

 

I model a 2D plane stress of a plate with center hole and a separate circle surface that is same location as the hole to simulate a neat-fit contact problem as shown below.

modelmodel

However, from looking the results, it seems like the hole deforms too much, and there is penetration between circle region and the hole edge despite the defined edge-edge contact. 

ResultResult

 

Can someone take a look at my model and let me know what may have gone wrong? Here is the link:my model

 

Thank you 

 

7 REPLIES
Solution
Solution
Accepted by topic author Cocoki
‎08-10-2016 09:12 AM

Re: 2-D Plane stress Neat-fit problem

HI,

 

Check first the real scale for the deformation. I guess your plot is with "exagerate" scale.

And then the pentartion value. If it is too much you can play with the contact settings

 

Solution
Solution
Accepted by topic author Cocoki
‎08-10-2016 09:12 AM

Re: 2-D Plane stress Neat-fit problem

Dear Cocoki,

I am not able to open your model:

Opening model file from Femap version 11.10. Temporary file being created: 
Reading...
Unable to open Student Version Model in this version.

But I suggest the following:

  • Apply symmetry and study 1/2 model: split your plate with hole & center circle model and apply the symmetry condition constraining on edges the translation in the axis normal to symmetry plane, this will stabilize the center circle for contact condition.
  • Use a better quality QUAD mesh, draw a circle around the hole to imprint the surface and get a washer-like surface, this way you will have perfect QUAD 4-nodes elements around the hole.
  • In CONTACT is very important that node location of both CENTER CIRCLE & HOLE PLATE to be coincident in space, this will avoid interference or initial penetration between bodies.

initial_penetration0.png

And finally check the deformation scale factor, use 1:1, this way you will see real deformation, if penetration exist then it will appear clearly in the screen.

Best regards,

Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Re: 2-D Plane stress Neat-fit problem

Thank You very much. You are right about the exagerated scale. The actual deformation is much less.

Re: 2-D Plane stress Neat-fit problem

Ok. I supposed that. One must take care about it. The plot is the plot and one can play with scale parameters. The results are the real things. You should check the penetration. Let`s say that if the displacement is 1mm penetration should be 0.0001 or less (or check with other contact parameters and check if the results change a lot. like a mesh converge study). Theoretically penetration is enforced to be 0 but augmented langrage method (I think It is the method used in sol106) gives some penetration (less iterations than forcing 0). It is a comprimise between iterations/results

Re: 2-D Plane stress Neat-fit problem

Hi jon_morga,

 

 

How can I perform a penetration check in Femap? 

Re: 2-D Plane stress Neat-fit problem

Hi,

 

I think with contact separation. I do not remmeber now but:

- positive: separation

- negative : penetration

 

But I am not sure. Check it if it has sense. I eman if it is opening you have postive or not

 

Re: 2-D Plane stress Neat-fit problem

Thank you!