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Moment diagram along a 3D beam
Posted 19.03.2016, 15:11 GMT-4 Geometry, Structural Mechanics Version 5.2 2 Replies
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Hi,
I am new to COMSOL and having problem with extracting moment diagram from a 3D cantilever beam under various loads. I have applied loads and moments at the free end of the beam and defined the plastic properties of the material used in the model. Accordingly, I do not want to calculate the resultant moments by using the structural analysis formula ( F*d=M), but I was hoping COMSOL could calculate the resultant moment at each section of the beam and present the moment diagram along the beam length as a result.
I have used the "probe" feature for this matter and been unsuccessful (Probe gives the reaction moment of just one section).
Any help is appreciated.
Thank you
I am new to COMSOL and having problem with extracting moment diagram from a 3D cantilever beam under various loads. I have applied loads and moments at the free end of the beam and defined the plastic properties of the material used in the model. Accordingly, I do not want to calculate the resultant moments by using the structural analysis formula ( F*d=M), but I was hoping COMSOL could calculate the resultant moment at each section of the beam and present the moment diagram along the beam length as a result.
I have used the "probe" feature for this matter and been unsuccessful (Probe gives the reaction moment of just one section).
Any help is appreciated.
Thank you
2 Replies Last Post 23.03.2016, 11:06 GMT-4
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Posted:
9 years ago
Hi
On the attached (fixed) side you can use the reaction Force/Moment variable that COMSOL calculates for you (solid.RFx, solid.RFy, solid.RFz), and the moments (sold.RMx, solid.RMy, solid.RMz)
However if you are "inside the materials" (else than on the fixed boundaries) you cannot extract these "reaction" values. One way around is to cut the beam a few times with internal boundaries, and then integrate the Traction force densities (another COMSOL internal variable) that is defined on all Boundaries. See 2D example attached. Traction force integration is less accurate than the reaction force calculation (check the BLOG and the KB Knowledge Base for explanation on precision of flux calculations by FEM)
And check the doc for details
--
Good luck
Ivar
On the attached (fixed) side you can use the reaction Force/Moment variable that COMSOL calculates for you (solid.RFx, solid.RFy, solid.RFz), and the moments (sold.RMx, solid.RMy, solid.RMz)
However if you are "inside the materials" (else than on the fixed boundaries) you cannot extract these "reaction" values. One way around is to cut the beam a few times with internal boundaries, and then integrate the Traction force densities (another COMSOL internal variable) that is defined on all Boundaries. See 2D example attached. Traction force integration is less accurate than the reaction force calculation (check the BLOG and the KB Knowledge Base for explanation on precision of flux calculations by FEM)
And check the doc for details
--
Good luck
Ivar
Attachments:
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Posted:
9 years ago
Thank you so much Ivar, your answer to my question along with the sample model was really helpful. Accordingly, I was working on evaluation part and, as you said, got the approximation of the resultant section moments. However, demonstrating the moment diagram by using the table is challenging for me. The resultant table has 10 evaluated moments for 10 cut sections respectively, but I was not able to draw the moment diagram. It would be very nice of you to help me on this too. I have provided my model for your reference.
Thanks,
Mahmoud
Thanks,
Mahmoud
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