Problems with Surface Contact

[Anonymous]

Hi, 

I am working on replicating a problem we had in our facility a couple of days ago, where a small metal chip got inbetween the back of a seal face and the seal face carrier and caused issues. I created a basic model in Inventor, where I added a small extrusion to replicate the chip, then mated the back of the floating seal to the surface of the chip. Then I opened it in simulation mechanical and put a force on it, forcing the seal into the carrier. The goal was to see how the seal rested in the carrier with the chip under it when force is applied, however, no matter what i do for contact setting, the seal just passes right through the seal carrier when it shows the dislocation. Any Ideas?

[KubliJ]

Hi @Anonymous,

Unfortunately I am not able to use your attached model.  It opens to a empty model file.  So, my following advice is going to be a little generic.

First and most likely issue will be with the loading.  I do not recommend using a force, instead use a Prescribed Displacement.  You can ramp it up slow enough and then stop the analysis when the reaction forces match your intended force.  This adds stability to the load and also ensures that there is not too much motion that the solver misses it.  This I am thinking is the most likely best fix for you.

The other possible issue is too large a time step.  Parts are moving too much between steps that contact is not initiated.  Reducing time step size may help.

Outside of that, not sure what the issue might be without looking at the model.

Thanks,

James

[Anonymous]

Hi, 

Much apologies for the bad attachment. I have included some pictures for your review. The first photo shows the forces and constraints, while the second and third show the chip I made in the seal carrier. The force that I applied to the seal face is a force that exist in our operation and I also want to see it's affect on the floating seal with the chip. 
Thanks,

Jim 

[KubliJ]

Hi Jim,

I see that you are running a linear static stress analysis.  In Simulation Mechanical, for contact to occur, parts must already be in contact and have a matched mesh between the two faces.

Also, you may want to consider using symmetry to better constrain the model.  the part you are pushing down on appears to rely only on contact to keep in in place.  If you use quarter symmetry, it will give you two split (symmetry) planes to constrain the model to.

Thanks,

James

[KubliJ · Accepted solution]

Something to add is that you may want to consider a non-linear (MES) analysis.  MES can handle a gap, especially if you are looking for the effects of impact.

Thanks,

James

[Anonymous]

Unfortunately, 
I have tried a nonlinear analysis and I'm still having the same issues despite what I put in for the timestep and distance. One idea I had was to set up a impact plane for the seal and have it line up with the back of the groove the seal would fall into, but after I applied to I received an error that stated that "nodes were detected on both sides of impact plane" or something of that caliber. Would it be possible to make an impact plane only applicable to one part? and not the other? 

[John_Holtz · Accepted solution]

Hi @Anonymous

My suggestion is to try the archive again (app button > Archive > Create > Model Only). That would be the best way to get the material properties, loads, etc.

The impact plane will not work. As you suspected, it applies to the entire model.