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slippage/tolerance between threaded hole and a hole on simulation

Question asked by Arkmando Arratia on Jun 19, 2014
Latest reply on Jun 25, 2014 by Jared Conway

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Hi guys,

I have a threaded hole 30 mm in diameter on one plate steel a-36 and a 35 mm hole on another plate steel 4140. When I try running a thermal simulation both materials expand at different rates. The holes can be adjusted for a 2 1/2 thousandths of an inch which will cover a lot of stress generated. My problem is that I do not know if solidworks can account for this? When I fix both holes (concentric) I see stresses much higher than the materials resistance which I think is because the materials do not have any tolerance to move and starts generating stresses right away. delta temperature is 200F.

Regards,

Arkmando

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Shaun Densberger Jun 19, 2014 1:58 PM
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When I try running a thermal simulation both materials expand at different rates.

Are you doing a thermal simulation, or are you applying a temperature load in a structural analysis? Do both materials have the same coefficient of thermal expansion?

The holes can be adjusted for a 2 1/2 thousandths of an inch which will cover a lot of stress generated. My problem is that I do not know if solidworks can account for this?

I don't understand what you mean by this; can you provide further explanation? Are you saying that there's a 0.0025" clearance between the plates?

When I fix both holes (concentric) I see stresses much higher than the materials resistance which I think is because the materials do not have any tolerance to move and starts generating stresses right away.

I don't understand what you mean by this; can you provide further explanation? Are you applying a fixed constraint on the inner surface of the holes?
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- Arkmando Arratia @ Shaun Densberger on Jun 20, 2014 10:03 AM
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  Hi Shaun,
  
  Are you doing a thermal simulation, or are you applying a temperature load in a structural analysis? Do both materials have the same coefficient of thermal expansion?
  Static simulation with thermal loads
  
  The holes can be adjusted for a 2 1/2 thousandths of an inch which will cover a lot of stress generated. My problem is that I do not know if solidworks can account for this?
  I would like solidworks simulation take into account the tolerance I have added to my axle to reduce stress concentrations. I ran 2 simulations one with both parts having the same diameter and the second one with one parte being -.022" smaller. I get the same results, same stress concentrations.
  
  When I fix both holes (concentric) I see stresses much higher than the materials resistance which I think is because the materials do not have any tolerance to move and starts generating stresses right away.
  In the study I have set global bounded to global contact bonded and contact set as no penetration between the outer and inner faces of my model. I believe that these set up bonds both parts together and denies all slippage. What connection should I use if I want slippage?
  
  Thank you for your time
  Arkmando
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Jared Conway Jun 19, 2014 6:41 PM
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what is the goal of the analysis?
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- Arkmando Arratia @ Jared Conway on Jun 20, 2014 9:47 AM
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  Hi Jared,
  The goal of my analysis is to determine the fit needed between and axle and a bearing. they both have different temperatures and if I set them with the same opening/diameter they generate very high stresses. I would like to add a tolerance to the axle h6 -.022" smaller than the bearing diameter to reduce the stresses. I have already done this but stresses do not change, they remain exactly the same. Is there a way to reduce stresses in my analysis be doing something like this or should I take a different approach?
  
  Regards,
  Arkmando
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  - Jared Conway @ Arkmando Arratia on Jun 20, 2014 5:49 PM
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    what element size are you using?
    
    what change are you expecting?
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    - Arkmando Arratia @ Jared Conway on Jun 24, 2014 3:26 PM
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      -I am using 20mm element size. Does than mean I should use smaller element size of at least .5mm?
      
      -I am expecting a decrease in stress between the axle and the bearing
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      - Jared Conway @ Arkmando Arratia on Jun 25, 2014 12:43 AM
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        20mm element size and a tolerance of 0.022". how will the mesh be able to capture that small of a feature with such a large element size?
        
        even if you mesh at such a small amount, i think the change in stress that you're expecting will be in the level of accuracy from an FE solution.
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slippage/tolerance between threaded hole and a hole on simulation

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