Contact problem

[AndreCagliari]

Hi,
I'm working on a contact problem on a total knee prosthesys, and I'm starting with a simple preliminar problem: a sphere pressed on a block by a vertical force (both elements are made of steel).
My problem is that there is no contact:the sphere penetrate into the block without any visible deformation,and there is a node (that rappresent the initial contact between the two bodyes)that stay near the initial position.
Someone can tell me whych are the parametres that i can modify to solve this problem?
I don't know if there is only a visualization problem, or if contact wizard can do some problem (now I'm tryng to define contact without using contact wizard).
thanks

 

[elogesh]

Hai,

There is one example contact problem in ANSYS verfication manual similar to your problem.The results are verified with mechanical engineering design by shigley.

Few simple tips are,

Use surface to surface contact elements with default contact parameters.

Use style->displacement sacling->1

Use finer mesh around the contact regions.

We need few more error or warning information from you inorder to give further sugggestions.

Logesh.E

 

[mnaeem]

I have two plates in contact with each other. Top one is steel and the bottom one is concrete. Both the plates have been meshed with 8node solid45 elements. Between these plates, there is a pair of Target 170 and Contact 173 elements. When I try to solve the problem following message pops up "Target element is attached to Solid element, solution may not converge".
I am using default real constraints for contact pair.

Does any body have any idea what does this Warning mean?

 

[JaStKn]

Are your contact pairs ok?

Contact and target elements must have the same realconstants!

esel,s,real,,?

Also looking for the elementnormals of the contact elements!

esel,s,real,,?
/psym,esys,1

They must be opposed!

 

[mcintya]

Use the contact manager and plot the normals for the contact pair, make sure the point towards each other. You could try swapping the contact and target elements. The contact elements generally have a finer mesh than that of the target elements.

 

[maxPE]

Contact is non linear and Im still amazed at how many engineers think that it is a slam dunk. Make sure that you have the contacts on the correct surface and targets on the correct surface. (read ALL of the help on contact!)Reversing these can often turn a horrible pbm into an easy one. Also try full symetry..contacts and targets on both surfaces. In additon you may as a last resort change the pinball region and other parameter of the contacts...use this approach as a last resort. Try taking a section and doing a axisymetric problem first and see if that converges. Youve bitten of alot!

Max