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cable rolling

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Hi,

I am trying to model a cable (or a single thread) rolling over a bend raduis. In reality it will be rolling between two plates but its easier to picture it as if its rolling over a pulley. When I try to apply the necessary constraints (perscribed velocities or fixed constraints), and then solve it. I dont get the movement I am looking for...instead a distorted looking cable. The applied conditions are obeyed but the movement of the cable that I want is not!

Any help here would be much appreciated.

Cheers,

Chris

4 Replies Last Post 2010年9月28日 GMT-4 09:03
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2010年9月27日 GMT-4 10:59
Hi

which physics are you using (and which version): truss, beam, solid or home brew ?

Have you checked the degrees of freedom (free , elastic ...) of your system ?

--
Good luck
Ivar
Hi which physics are you using (and which version): truss, beam, solid or home brew ? Have you checked the degrees of freedom (free , elastic ...) of your system ? -- Good luck Ivar

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Posted: 1 decade ago 2010年9月27日 GMT-4 11:10
I am using solid mechanics in version 4.0a. To help you visualise the model, it is modelled as a thin cylinder (0.405 mm diameter) rolling over a bend radius of 4 mm through an angle of 180 degrees.

What exactly do you mean when you ask about the degrees of freedom? where would i check this? I have tried the following:

Fixing one end and prescribing a velocity to the other.
Applying velocities to both ends.
Applying similar constraints to other parts of the strand for continuity.
Applying physical constraints (Such as a pulley, which the strand then moves through!)
And various combinations of above.

Thanks,

Chris
I am using solid mechanics in version 4.0a. To help you visualise the model, it is modelled as a thin cylinder (0.405 mm diameter) rolling over a bend radius of 4 mm through an angle of 180 degrees. What exactly do you mean when you ask about the degrees of freedom? where would i check this? I have tried the following: Fixing one end and prescribing a velocity to the other. Applying velocities to both ends. Applying similar constraints to other parts of the strand for continuity. Applying physical constraints (Such as a pulley, which the strand then moves through!) And various combinations of above. Thanks, Chris

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2010年9月28日 GMT-4 08:19
Hi

the DoF for me was : rope = basically one DoF tension (or truss model),
while a solid (if you do not set specifically the anisotropy stiffness tensor) is a bulk "solid" "rod" and not really a "rope"

--
Good luck
Ivar
Hi the DoF for me was : rope = basically one DoF tension (or truss model), while a solid (if you do not set specifically the anisotropy stiffness tensor) is a bulk "solid" "rod" and not really a "rope" -- Good luck Ivar

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Posted: 1 decade ago 2010年9月28日 GMT-4 09:03
I see what you are saying but the problem is that I want to apply a prescribed velocity, not a load, which you cant do in truss or a beam.

Also surely the model should behave according to its geometry and material properties as opposed to its physics type, no? Just the physics type determines what constraints can be set or am i wrong here?!

Thanks,

Chris
I see what you are saying but the problem is that I want to apply a prescribed velocity, not a load, which you cant do in truss or a beam. Also surely the model should behave according to its geometry and material properties as opposed to its physics type, no? Just the physics type determines what constraints can be set or am i wrong here?! Thanks, Chris

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