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Active Member
Cubed-I
Posts: 6
Registered: ‎05-08-2012
Accepted Solution

Twisting Motion about a parts axis In Mechanical or Inventor

804 Views, 7 Replies
09-21-2012 06:26 PM

I am looking to generate a twisting force on a part, and for the life of me I cannot seem to find the correct combination of commands to generate this in Autodesk mechanical 2012. I can perform this operation in Anysis (At my old employer) but currently do not have access to anysis anymore. So I am looking for a little help. This is my first week tearing into Simulation so I am very limited in the operation of the program. (I have already done the hand calculations but Pretty Pictures can sometimes help people understand/interpret your results more quickly)

 

Anyone know how to do this? I flipped through all the tutorials and did not see a clear defined way of doing it the closest way I have seen is to add it through beam, (On the Model tree far left hand side)  then element def. but I can only set a radius and I cannot add any loads. 

 

Any help is appreciated. 

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Active Member
ilyasramdzan
Posts: 7
Registered: ‎05-22-2012

Re: Twisting Motion about a parts axis In Mechanical or Inventor

09-23-2012 10:25 PM in reply to: Cubed-I

Hi,

 

What I understand from your description is that you intend to apply a moment on a surface, no? If that is the case, in Simulation Mechanical 2012, you will need to add the beam as you cannot directly apply a moment to brick elements (brick elements do not transfer rotation).

 

If you have access to an upgrade to the 2013 version, I suggest you perform the upgrade as the developers have added a surface moment load.

 

Regards

Ilyas

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Active Member
Cubed-I
Posts: 6
Registered: ‎05-08-2012

Re: Twisting Motion about a parts axis In Mechanical or Inventor

09-24-2012 04:17 PM in reply to: ilyasramdzan

Ilyas

I am useing the beam function. And I did try a surface moment which makes the end blow up like a balloon. It dose not twist it. 

 

I want this as shown in the U Tube clip.  http://www.youtube.com/watch?v=BB4mI7OmiuU&feature=BFa&list=HL1348523847

 

 

Not This as shown below

 Twist.png

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Active Member
ilyasramdzan
Posts: 7
Registered: ‎05-22-2012

Re: Twisting Motion about a parts axis In Mechanical or Inventor

09-24-2012 08:20 PM in reply to: Cubed-I

Hi,

 

I cannot find the 'beam function' that you are talking about. Perhaps you are working with line elements (just one line to define the whole beam), but the image you provided showed otherwise. Anyway, to simulate something like the youtube video, you will need to have use 3D element (such as bricks) in order to get the local stresses at the cross section. I did an example using MES analysis, fixed one end and applied a surface moment on the other. The results look something like this.

 

torsion.png

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Regards

Ilyas

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Valued Mentor
AstroJohnPE
Posts: 498
Registered: ‎08-30-2012

Re: Twisting Motion about a parts axis In Mechanical or Inventor

09-25-2012 09:12 AM in reply to: Cubed-I

My guess is that you are using Linear Static Stress which is acceptable for small displacement only. The video you referenced is using a large displacement solution since they are twisting the tube 180 degrees.

 

So, chances are your results are correct -- assuming that you are twisting the tube a small amount (a few degrees?). See the attached image to understand why the end blows up like a balloon.

 

If you are twisting the item more than what linear stress can handle, then you need to use a nonlinear solution, such as "Analysis > Type > Nonlinear > Mechanical Event Simulation".

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

16 years experience with Simulation Mechanical
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Active Member
Cubed-I
Posts: 6
Registered: ‎05-08-2012

Re: Twisting Motion about a parts axis In Mechanical or Inventor

09-25-2012 02:32 PM in reply to: AstroJohnPE

Thanks John,

 

I used to do a lot of Frame Twist in ansys on Custom Tractor trailor frames and could get it to work. And after your little update I got it to work the same way in Simulation. Thanks again!!!

 

Cheers

Craig

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New Member
aryudhi76
Posts: 1
Registered: ‎07-31-2013

Re: Twisting Motion about a parts axis In Mechanical or Inventor

07-31-2013 09:54 AM in reply to: ilyasramdzan
Hi Ilyas.

Do you have tutorial with twisting motion?
because i have any problem same with your sample for my study

Many Thank's
Dedy
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Distinguished Contributor
ilyas
Posts: 139
Registered: ‎06-13-2012

Re: Twisting Motion about a parts axis In Mechanical or Inventor

08-01-2013 01:28 AM in reply to: aryudhi76

Hi,

 

I don't know if there is an exact tutorial on this but this one should get you going. The CAD model may be a bit different, but just imagine that the model is one straight shaft. Prior to version 2013, you will need to create beam elements to apply nodal moments and transmit it to Brick elements(as brick elements only support 3 translational DoF). However, as of version 2013, you may straight away apply surface moment onto Brick elements.

Also note that the tutorial features Static Stress analysis which only considers small displacement. If you are experiencing large deformation, then you will need to use MES analysis.

 

Regards

Ilyas

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