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Attached is a cross-section of a proposed cantilever roof section. I aim to support the end with a cable that extends over a central pier to the other side. How can I model the cable so that the tension is equal on both sides? Is there a way to model a pulley support at the top of the pier?
Using "truss bars" type instead of cables ,You can force the horizontal component of the 2 " cables" to be the same by setting a shear release on the mast top in the same plane of the mast and the 2 cables..
If the mast local axes are not aligned with the cable directions then you will have to adjust it with Geometry/properties/ gama angle
Rafael Medeiros
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that is the Releases dialog window , but as releases are set in terms of bar local axes , you will have to mark Uy or Uz as released ,depending on which of these 2 axes is aligned with the 2 "cables" plane
Rafael Medeiros
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I created a simple example of what I am trying to accomplish. I linked two bars by a pin support and applied loads in opposing directions. I am still a bit unsure of the modelling procedure.
This is what I meant on my posts
No shear force on the mast on the released model , so all horizontal forces come from the 2 " cables"
Do the math and you will see that the cables horizontal components are the same
Rafael Medeiros
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@tau_oragami said in message 1:
How can I model the cable so that the tension is equal on both sides?
I think it’s not possible.
M. Agayr
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In fact there is a way to to do it!!!
I changed the structure type on Geometry menu to Frame 2d to avoid unecessary instability warnings on non relevant directions to this model.
Then I edited the mast top geometry to simulate the cable around a pulley device . Cable angles became slightly different in this process ,compared to the original model
Everything was done with truss bars
Unreleased model would be the most common choice for this type of structure
Mast top node released for shear , my 1st suggestion has the strongest point ,as a side effect, making the mast moment Zero all the way to the bottom as there is no shear on mast top. Mast axial force are way higher though.
But I think it would be hard to build that shear release on real life.
Pulley system , good exercise , but in this case/model geometry ,I don´t see much difference compared to standard model . And never saw that also in real life.
Test model attached
Rafael Medeiros
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Hi @Rafacascudo
But I think it would be hard to build that shear release on real life.
Pulley system , good exercise , but in this case/model geometry ,I don´t see much difference compared to standard model . And never saw that also in real life.
I agree
Very great approach to model a pulley.
Can be used in lifting systems
M. Agayr
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