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sriramsheval
Posts: 18
Registered: ‎10-21-2013
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Doubt about Analysis Approach

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11-12-2013 01:46 AM

Hi,

 

I'm Working on a static stress analysis, where I have to find the stress generated on wire due to applied torque on screw (see Cut sectional view of the model below). I made the analysis with the model below by applying the axial force (calculated from given torque) and performed the analysis.

1.JPG

 

My Colleague, contradicts with me that, I have to make a thread feature and assembly it with its mating threaded body and perform the same analysis. (See threaded model below)

2.JPG

 

Can any one please suggest which is the right method (Note: Thread strength/stresses generated is not in interest)

 

Should such/similar analysis, must be performed with/without thread, which is advisable and WHY?

 

Thanks in advance

Sriram

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Valued Mentor
Posts: 459
Registered: ‎08-30-2012

Re: Doubt about Analysis Approach

11-13-2013 06:12 AM in reply to: sriramsheval

 

Hi Sriram,

 

Did your colleague give any justification for his more complex analysis? The screw threads will require vastly more brick elements and more contact elements in parts that are not of interest. Also, applying an axial force would only make contact between the screw threads and the body threads. You would need to apply a torque to the screw (instead of an axial force) in order to move the screw into contact. Depending on the angle required to turn the screw, you may need to perform a large displacement analysis; that is, an MES analysis. So you made a simple model that runs in a short time (10 minutes?) into a moster that will take a day to setup, tune, and run. Why?

 

You may be missing one detail in your description. In real life, the force of the screw pressing on the wire is counter-balanced by the screw threads putting an equal and opposite force on the body. So you need to apply a surface force to the "thread" surface on the body. If you have both loads, your model includes all of the effects with a much simpler model.

 

That's my suggestion.

 

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

16 years experience with Simulation Mechanical
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Contributor
sriramsheval
Posts: 18
Registered: ‎10-21-2013

Re: Doubt about Analysis Approach

11-14-2013 01:23 AM in reply to: AstroJohnPE

Hi John,

 

I was thinking of the same way, but I was not sure.

 

So I posted here to get suggestion form experts.

 

Thanks for your suggestion.

 

Sriram

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