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OptimistishHerr1-Visitor
1-Visitor
April 29, 2019
Solved

Problem in specifying rotation constrainsts

  • April 29, 2019
  • 1 reply
  • 13192 views

Actually, i am working on a differential which getting some forces from pinion.

 

These forces would make an impact on the body to rotate bolt in x-direction.

 

So, i want to hold the bolt in x-direction of rotation to see the effects of forces.

 

But as i am doing this i am geeting a warning that these constrainsts wont make any effect. 

 

Ihow should i move forward to analyse the case correctly 

Best answer by SweetPeasHub

Yes a cylindrical csy (created in simulate mode) is a way to do this.  Always attempt a Free Body Diagram.  You seem to be missing the loads/constraints at the output shafts. (R in my image).

 

Also, the pinion load may be statically redundant if using 2 pinion gears as is typical.  The load may be higher on one pinion gear than another based on manufacturing tolerances and wear.  I would not assume full halving of stress and load is happening due to the 2nd pinion gear.   

 

Also see this for my quiz on mechanizing a differential.

 

 

FEA RING GEARFEA RING GEAR

 

 

 

 

1 reply

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ChrisKaswer16-Pearl
16-Pearl
April 29, 2019

A basic, fundamental fact of 3D solid elements is that they do not/cannot possess DOF in rotational directions. I will assume you are modeling the areas you wish to apply rotational DOFs with solid elements. If so, Simulate will not allow this type of constraint. Some codes allow for "tricks" through clever interface coding to allow some application of rotational BCs - and these are usually limited, like the "TLAP" in Simulate.

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    OptimistishHerr1-VisitorAuthor
    1-Visitor
    April 29, 2019

    Thank you for your answer Chris

     

    What should I do in such case if I want to restrict the rotation?

     

    If it was not possible, then it would have been shown greyed. But at this point, i can apply it but it's not making an effect.

     

    Am I doing something wrong while defining other parameters or its just not possible?

    C
    ChrisKaswer16-Pearl
    16-Pearl
    April 29, 2019

    Can you use a pin/cylindrical joint constraint? This should allow you to trap the desired direction.

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