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Contact Bushing press-fit in sleeve

7 REPLIES 7
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Message 1 of 8
jrm_1971
1308 Views, 7 Replies

Contact Bushing press-fit in sleeve

I have a contact where the outside diameter of the bushing shown is a surface-to-surface with the inside diameter of the sleeve. Dimensionally, the bushing OD = sleeve ID, so metal to metal press fit

 

There are two contact pairs, surface-to-surface on the same sides of symmetry

 

Analysis: MES with non-linear material models

 

Mesh is all bricks:

 

Material (just standards out of SIM 2011)

Sleeve: Alum. 6061-T6

Bushing: Brass (knowing real world is bronze but that's not a standard option in SIM Pro 2011)

 

For the nodal predescribed displacement (translation), the load curve is set to time: 0, multiplier 0 and time: 4,  multiplier: 1

 

Element data: Large displacement, isotropic elastic

 

No midside nodes included in the element data

 

Contact Problem Type: Low speed contact press-fit

Contact Method: frictionless

Contact Type: Automatic

 

Analysis Type:

Duration: 4 s  and Capture rate: 20

 

Stops at 3 out of 80 time steps, there is this error in the log "

** Error : reading restart file, r9. restart file recording element group data is corrupted. Resume or restart job can not be completed. This happens, when original job was terminated improperly."

 

Problem is I am expecting the bushing to fully "insert" into the sleeve (i.e. fully displace in -Z by 1.3) and it's only displacing -4.085e-6 as well as give the stresses. It's not doing it. I have tried various other contacts and Nodal BC symmetry about Z along where planes XZ and YZ cut through the bushing wall.

 

 I have been through both Mirza's and Shoubing's AU tutorials. I also tried Rz to make sure there's no FBM.

 

Time to call in help.

 bushing contact.png

bushing contact disp.png

bushing contact stress.png

7 REPLIES 7
Message 2 of 8
jrm_1971
in reply to: jrm_1971

I just ran this with tet mesh and even though it went through all 80 time steps, no improvement on the stress and displacement. Please help.
Message 3 of 8
John_Holtz
in reply to: jrm_1971

Hi jrm,

 

First off, I think you are misinterpreting the red flag "penetration = 4.085E-6". Your figure shows that the top part has moved -0.049 in the Z = -1.3 inch total travel * (3 steps out of 80 steps). So the bushing has moved that far into the sleeve. Correct? (assuming that the bushing is "resting" on top of the sleeve at time 0)

 

The red penetration flag indicates that the OD of the bushing has penetrated the ID of the sleeve by 4.085E-6 inches. It's hard to tell from the figures, but if the bushing OD = sleeve ID, then there should be no interference, therefore no stress and very little force to move the bushing. If the solution is generating stresses, it is either because the contact distance is larger than 0 and you have created a mathematical interference, or the mesh is creating the problem described in Figure 2 on the Help page "Simulation Mechanical > English > 2013 > Help > Simulation Mechanical > Setting Up and Performing the Analysis > Analysis-Specific Information > Nonlinear Analyses > Loads and Constraints > Surface-to-Surface Contacts > Advanced Controls".

 

I may be misinterpreting things because I cannot get a full resolution image from the post. If you cannot determine exactly what is occurring, please consider attaching an archive of the model to a reply. See "Create, Post, or Provide an Archive of your model".



John Holtz, P.E.

Global Product Support
Autodesk, Inc.


If not provided already, be sure to indicate the version of Inventor Nastran you are using!

"The knowledge you seek is at knowledge.autodesk.com" - Confucius 😉
Message 4 of 8
jrm_1971
in reply to: John_Holtz

John,

 

Thank you for that. However, regardless of what is shown in the pictures, the analysis is not reaching the ultimate goal with the BCs I gave: To fully insert the bushing into the sleeve under press-fit conditions. ie if the bushing is 1.3" and the sleeve is 1.3", the bushing should press fully into the sleeve. Under real world conditions, for a metal-to-metal press fit, in theory, I would expect some stress, hence, if you were in machine shop, the press fit would require either an arbor or hydraulic press. The pressure (stress) in compression.

 

I reviewed http://wikihelp.autodesk.com/Simulation_Mechanical/enu/2013/Help/0031-Autodesk31/0237-Setting_237/02...

and get it. However, in real world conditions, wouldn't one expect the math model to emulate the "press"? BTW, I did the User-specified option for contact distance, didn't help.

 

Basically, how is the ultimate goal reached? I thought this would be really simple exercise.

 

Message 5 of 8
John_Holtz
in reply to: jrm_1971

Hello,

 

Without having your model, it is difficult to know what is going on.

 

I created a similar model and ran two analyses:

  1. No gap, no interference between sleeve and bushing
  2. 0.003 inch interference between sleeve and bushing.

Open the archive with Mechanical / Multiphysics AFTER removing the false extension of ".txt". I did not include the results do to the size of the archive, but it only takes a few minutes to analyze.

 

Let us know if there are any questions.

 

 



John Holtz, P.E.

Global Product Support
Autodesk, Inc.


If not provided already, be sure to indicate the version of Inventor Nastran you are using!

"The knowledge you seek is at knowledge.autodesk.com" - Confucius 😉
Message 6 of 8
jrm_1971
in reply to: John_Holtz

Astro,

 

I tried to open the FEM file and cannot because it's 2013. I have 2011.

Message 7 of 8
jrm_1971
in reply to: jrm_1971

AstroJohn,

 

I tried to open your model and cannot since it is 2013. Also, to invoke the interference of 0.003 did you do that with the geometry (i.e. make the bushing OD 0.003 over the sleeve ID) or did you do that with the software? I am not seeing that option in 2011 SIM Pro nor how to invoke the results like you have done.

Message 8 of 8
John_Holtz
in reply to: jrm_1971

Hi JRM,

 

I think there are two options in regard to the different versions of the software that we are using

:

1) You upgrade your software to version 2013. Then you can open the archive that I provided.

 

2) You provide the archive of your model, and anyone with version 2011 or newer can check it out to see what is happening. Detailed instructions on how to do this are given in the post "Create, Post, or Provide an Archive of your model".

 

For the second item related to the interference, it looks like either method could be used in your situation. However, it is much easier to make the change in the software rather then updating the CAD model numerous times -- if you were to try multiple interferences. The distance between the two surfaces when contact is initiated is entered as follows:

  • right-click on the contact pair in the browser.
  • Choose "Settings".
  • Click the "Advanced" button.
  • On the General tab, set the "Contact distance" to "User-defined" and enter the distance: the interference fit in this case. (In version 2011, it is "Contact tolerance > User-defined")

 



John Holtz, P.E.

Global Product Support
Autodesk, Inc.


If not provided already, be sure to indicate the version of Inventor Nastran you are using!

"The knowledge you seek is at knowledge.autodesk.com" - Confucius 😉

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