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ehaenen1-Visitor
1-Visitor
December 8, 2015
Solved

Enforced displacement, tangential direction, more than 1 revolution

  • December 8, 2015
  • 13 replies
  • 6965 views

I've been doing some experimenting with large deformation analysis.

I want to twist the end of the beam around, several times (don't ask why, I just need it done).

In a large deformations analysis you can not prescribe a tangential displacement in radians. It has to be "unit of length" mm in my case. So I did this for the circular curve on the end of the tapered bit

I get it to rotate about 360 degrees, no further, however large I make the value for prescribed displacement (the value in the field is now 9000mm (160 full turns....).I stopped the analysis after I found out that displacements no longer increased.

Picture 1.jpgPicture 2.jpg


Any body knows how to tackle this?

Shall we classify this as a bug?


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Best answer by JonathanHodgson

What about the "interpret angular translations in radians" check-box?

Could you attach your end face to a single point using a rigid link (or a weighted link and a spring), and apply a rotation to the point?  You could try applying that rotation in a Cartesian csys to see whether that works any better...

13 replies

J
JonathanHodgson13-AquamarineAnswer
13-Aquamarine
December 8, 2015

What about the "interpret angular translations in radians" check-box?

Could you attach your end face to a single point using a rigid link (or a weighted link and a spring), and apply a rotation to the point?  You could try applying that rotation in a Cartesian csys to see whether that works any better...

E
ehaenen1-VisitorAuthor
1-Visitor
December 8, 2015

Jonathan:

The interpret etc. is not allowed for large displacements, this is definitely large displacements, So I can not use the check box.

I'll try with the point and the link(s) as soon as my regular analysis completes, but I fear.......

Well let's not get ahead of that.

I'll keep you informed on the developments.

Erik

U
unickque1-Visitor
1-Visitor
December 9, 2015

I tried to circumvene te problem by applying a load instead of a displacement.

Unfortunately I seem to be running into the same limitation: the model runs fine up to 360 degrees, but does not want to go beyond 360 degrees rotation.

Declaring it a bug sounds like a good idea, let's hear why this is such an impossibility. If PTC wants to go nonlinear they should do it right.

E
ehaenen1-VisitorAuthor
1-Visitor
December 9, 2015

Jonathan

Rigid link and prescribed rotation around z-axis on the free point worked. looks great, Thank you!

Video Link : 6562

Will look into the instabilities, but this is 600 degrees of rotation.

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