highly distorted elements 2

[vinsce]

Hello !!

I need some advice concerning a problem of distorted elements that happens after a plastic/rubber contact (using conta174 and targe170). The geometry deals with 2 plates. The element used is solid187 with non linear activation. I refined the mesh at the contact interface.
I applied a non excessive load (100N) on the top plate and blocked the 4 lines of the bottom plate.

When I launch the calculation I have a problem that indicates "one or more elements have become highly distorted". If you need further information to answer my question, you can ask me whatever you need.

If someone has any idea to help me...

Thank you.

 

[EngineerTex]

I assume that this is ANSYS. Without seeing what the distorted part looks like, I can't be sure, but it probably isn't anything to worry about. If it really bothers you, you can refine the mesh further, but increase the refinement to the entire solid(s) as opposed to just the area at the interface.

I get that warning on a pretty routine basis and I've never encountered problems. Just look at a number of cross-sections and make sure that the deflection and stresses are flowing in a manner consistent with the loads and restraints. There may be a few elements which end up a little odd, but FEA is not a magical box. It has limitations and you will get hotspots where you know for a fact that the answer is wrong. But that doesn't make the rest of it incorrect.

Engineering is not the science behind building. It is the science behind not building.

 

[vinsce]

Thanks a lot,
Indeed this "error message" was predictable as the structure deformation is so important... Sorry I'm a beginner
Now I have another question that deals with a second contact that occurs after the load increases and I don't know how to face this problem. Maybe I can rise the load until the contact occurs and impose the contact conditions... Or maybe an ansys command exists but I didn't find it...

If someone has an idea...

Thanks !!

 

[GregLocock]

A picture is worth about 2796 words. Hint.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[vinsce]

Sure,

I would really appreciate some advice concerning my problem. You can find attach a picture describing the matter of my preoccupation.

Thanks a lot.

 

[Ron]

This could be caused by a large difference in moduli, particularly between the top plate and the "sandwich" layers. Check the compatibility of your material properties. You might need to model the interlayer as springs.

I'm not familiar with your particular FEA program, but have seen this in others.

 

[Ron]

Hey Greg...I only got 2795 out of the picture...does that mean you have the last word?

 

[vinsce]

Thanks Ron,

Good advice.

But I succeeded in solving my initial problem, I posted my second message because of the contact between the 2 bottom layers(cf picture)that occurs after the elastomer deformation.

I don't know what condition to take into account between the 2 surfaces that will be in contact during the load increment...
I'm working with Ansys Mechanical LS-Dyna

Thanks for all your previous answers.