Home Forums NextFEM Designer support forum Temperature gradients

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• #4797

Hello,
For example, consider a doble-fixed beam with a rectangular cross-section 0.20*0.60, and a “C25/30” concrete material. According to NextFEM database E = 31.476 GPa, alphaT = 0.00001.
The beam (see Attached NXF file) is subjected to two thermal loads:
The first load case generates an axial force of:
N = (10^-5)(15)(31.476*10^6)(0.20*0.60) = 566.568 kN.
NextFEM gives the same result (although compression).
Regarding the linear gradient, it generates the following moment:
Mz = (10^-5)(10/0.60)(31.476*10^6)(0.20*0.60^3/12) = 18.8856 kNm.
NextFEM gives Mz = -56.657 kNm, which is much different.
Any help will be greatly appreciated.
Thanks for the free basic version of the program.
Kind regards,
Luciano Jacinto
(PS: Thermal loads in the model were assigned via GUI, because apparently there is no API method to add thermal loads via Python, which I would prefer. Do you consider implementing this method in the future?)

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#4799

In the case of uniform gradient the result given by NextFEM (compression) is obviously correct. The doubt is only about linear gradient.

#4800

Dear Luciano,

Regarding the sign of temperature gradient: starting from a user’s dT, the gradient is applied to the section as to have -dT/2 on the positive Y+ face of the section, and dT/2 on the negative Y- face of the section. We’re evaluating to invert this sign as to have positive temperature on Y+.

#4805

Dear Luciano,