FEA Contact pressure

[Pauli666]

Has anyone used contact pressure, and is there a way to show separate stresses across Contact Sufaces (as i thought the tick box implied).

I wonder if i am missing something, as an example a rod inside a cylinder, why does one part show contact (rod) but not the part it is contacting (cylinder)? Any help appreciated.

[Pauli666]

Is anyone using the AIS2011 Pro, FEA module to model contact pressure?

Do I need to add more detail to get a reply, or supply the simple model?

Any help from ADSK?

[henderh]

Hi Pauli,

  I can reproduce the issue and I'll try to answer your questions the best I can.

1)  Contact Pressure result.  This is the pressure at the contact interface, it is not really related to the "stress across contact surfaces".  For example, you have an assembly of two cubes placed on top of each other.  On the bottom face of the bottom cube, add a frictionless constraint (a fixed constraint would restrict the "outward" movement of the face, i.e. create tangential stress components).  On the top face of the top cube, add a 1 MPa load.  Enable "Detect and Eliminate rigid body modes" in the simulation properties and solve.  You will see that the contact pressure result is very close to 1 MPa.

  To make it even more realistic and slightly better results, you can use a "Sliding / no Separation" contact instead of the default bonded contact for the same reason as the frictinless constraint versus the fixed described above.

However, you are right that the contact pressure shows zero on one of the components.  I've logged it as 1380663 and sent it on for Development's investigation.  Thank you for reporting this!

2)  "Separate Stresses Across Contact Surfaces" is an advanced option and would be difficult to show the effects of turning it on and off in a simple dataset.  It would only be of interest if you are concerned with the stress components (not contact pressure) at the contact surfaces, and the bodies in contact are different materials, and you are using a bonded contact. With this option off as default, we average the stresses across the contact faces (surfaces) instead of keeping them separate.

  I hope this helps explain this option and we appreciate you bringnig the contact pressue issue to our attention.

Best regards, -Hugh

[jasonrecords]

Hugh,

I am using Inventor 2012 and seeing this same issue concerning contact pressure, one of the components shows zero while the other mating componetn will show contact pressure.

Has this issue been fixed in more recent versions of Inventor?

Is there an issue with reliability of the results or can I assume the same pressure is on the opposite mating component?

thanks,

Jason

[davef]

I am using Inventor pro 2015 and experiencing this same issue.  This is an old thread... is it possible that this is still an open and unresolved problem or am I doing something wrong?

[rayessle]

I realise that this is an old thread but is there any idea when this is going to be fixed.

I have been trying to get a report out showing he contact pressures between a pin and two clevis plates to no avail. Inventor seems to apply the graphical representation results randomly to the parts in the assembly. I have-re done the analysis by copying the simulation in the browser and can sometimes see the pressure on the pin only, the clevis plates only or a combination of one clevis plate & the pin where it touches the other clevis plate. This is in inventor pro 2017. tried also in inventor pro 2018 and the same happens. Really need this fixed so I don't keep looking like I don't know what I'm doing when the client is looking over my shoulder. Also doesn't inspire confidence in the client when I have to tell them that it is a bug in the software. Now they are questioning if the results can be trusted.

Ray Esslemont

[johnsonshiue]

Hi Ray,

Do you mind sharing an example exhibiting the problem? It may or may not be the same as the old thread. Without files, it could be hard to tell.

Many thanks!

[rayessle]

File attached. 

3 of the simulations in the browser show only the contact pressure on the pin. The simulation titled "303kN PLATE MESH REFINED" shows the contact pressure on the top of the pin but not the bottom and also on the part half block 1.

Regards

Ray Esslemont

EDIT: Sorry, forgot to say files are Inventor 2017 Pro

[chad.schmidt]

I'm seeing this also. Could easily get confused for there being no contact pressure.  Very old thread.  Don't see this getting fixed anytime soon.

[JDMather]

I do not see any simulation set up in the files that you attached.

Did you intend to include an assembly file in the attachment?

[chad.schmidt]

No need to its already logged as 1380663.  There are great examples showing this in previous posts to this thread.

[rayessle]

Oops. Forgot the assembly. Here it is to go with the previous zip file above.

Regards

Ray Esslemont

[johnsonshiue]

Hi! You will need to attach all ipt and iam files. The top-level iam file does not contain all the geometry.

Many thanks!

[rayessle]

The other files are in the zip file in post 8. I just forgot to add the assembly there.

Regards

Ray Esslemont

[engfcavalcanti]

I´m using Inventor Pro 2018 and my stress analysis result shows zero contact pressure in one of the parts of my assembly. The assembly involve two parts, one axle and one ball bearing using interference contact h7/u6. The pressure contact at the surface of the axle shows 60-70MPa, but at the bearing shows zero.

[johnsonshiue]

Hi! This sounds like the loads or the constraints are not set up properly. Please share an example here so forum experts can take a look and comment further.

This is a very old thread. If you don't mind, please start a new one, since your issue may not be the same as this thread.

Many thanks!

[rayessle]

This is a known bug for as long as I can remember. Screencast below shows behaviour. Only one part shows the contact pressure.

Ray Esslemont

Inventor 2018

[engfcavalcanti]

Hi Johnson, I´m sorry about restarting this old thread, but I´m trying to validate the applicability of the Timoshenko (Strength of Materials, Part II) Thick Walls Pressure Vessels theory on interference contacts assembling axles and  rings. Checking the posts above (old posts), I didn´t  find  any solution for the problem, that the stress analisys just shows the pressure contact in one of the parts.

[johnsonshiue]

Hi Guys,

This does look like a bug to me. Contact pressure should appear in both contact participants. Otherwise, the system would be out of balance. I will work with the project team and understand this issue better.

Many thanks!

[Pauli666]

Hi Johnson,

"However, you are right that the contact pressure shows zero on one of the components.  I've logged it as 1380663 and sent it on for Development's investigation.  Thank you for reporting this!" H. Henderson 2011, its only been 7 years?