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bend to required diameter

Posted Oct 27, 2011, 6:57 a.m. EDT Structural Mechanics Version 4.2a 2 Replies

Niralamban Tiru
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i have a multiwalled tube made of different material to be bend to various diameters. to study the stress strain effect at these dia, what should i do? is it possible to bend a wire in required diameter
2 Replies Last Post Oct 27, 2011, 4:18 p.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Oct 27, 2011, 1:07 p.m. EDT
Hi

I'm not sure I', catching your question fully, but if you have a straight bar and you apply a moment on the end, fixed on the other you will bend it as a circular arc (or thereabout. BUT you MUST use large deformations. You could try with a rigid connector on the loaded end, and increase the moment y steps to see the bar curl and bend

--
Good luck
Ivar
Hi I'm not sure I', catching your question fully, but if you have a straight bar and you apply a moment on the end, fixed on the other you will bend it as a circular arc (or thereabout. BUT you MUST use large deformations. You could try with a rigid connector on the loaded end, and increase the moment y steps to see the bar curl and bend -- Good luck Ivar
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Oct 27, 2011, 4:18 p.m. EDT
If you use beam elements then do as Ivar described. The bending moment will cause a change in the radius of curvature of the beam (that will be uniform throughout the length of the beam). You also directly prescribe the rotational degree of freedom instead of applying a moment.

If you have a multi-material wall tube however, then you may have to model it with 3D solid elements. In that case it is harder to apply a moment/rotation since solid elements have no rotational degrees of freedom. You can achieve the same effect applying a Rigid Connector constraint to one beam end, and giving that constraint a prescribed rotation. There will be local stress concentrations at the two beam ends but in many cases they are negligible.

Nagi Elabbasi
Veryst Engineering
If you use beam elements then do as Ivar described. The bending moment will cause a change in the radius of curvature of the beam (that will be uniform throughout the length of the beam). You also directly prescribe the rotational degree of freedom instead of applying a moment. If you have a multi-material wall tube however, then you may have to model it with 3D solid elements. In that case it is harder to apply a moment/rotation since solid elements have no rotational degrees of freedom. You can achieve the same effect applying a Rigid Connector constraint to one beam end, and giving that constraint a prescribed rotation. There will be local stress concentrations at the two beam ends but in many cases they are negligible. Nagi Elabbasi Veryst Engineering

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