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Luciano JacintoParticipant
I understood your response. So, I run again the model with a zero Poisson coefficient (turning strains in both directions independent from each other) and got the same high result (sxx = 11805 kN/m2). So, the question seems a bit more complicated. I’m not an expert on FEM, but, perhaps it has to do with the shape functions, as you said. Thanks for your time spent on this.
Luciano JacintoParticipantMany thanks for your help. Ok, it makes sense that for shell elements NextFEM applies uniform temperature gradient simultaneously in both local directions. Ok, in my example, a monodimensional element would be more suitable, but this was simply to test NextFEM regarding uniform temperature gradients in shells.
So, continuing with my test, I corrected the model freeing displacements in the zdirection, and, after the analysis, the model behaves as expected, except for stresses in xdirection. NextFEM gives sxx = 11805 kN/m2, but I expected sxx = 7869 kN/m2. I would expect a closer result.
Once more, many thanks for your fast response.
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You must be logged in to view attached files.Luciano JacintoParticipantDear NextFEM admin and parhyang: Thank you both. Definitely, to estimate negative moments with some confidence in slabs at continuity supports we have to use finite elements with very small size near the supports (size in the order of magnitude of the slab thickness).
Luciano JacintoParticipantMany Thanks for your very fast response. Thanks also for the free, basic version of the program. What I like best is its very simple interface with Python, making it possible to construct a model in few minutes (using templates). For me, the GUI is good to view results, not so much to build the model.
So, we may conclude that, although the implemented finite element has the advantage of avoiding stress concentrations and peaks (which is the case in many situations, for example concentrated loads on shells), if there is some real peak, we must use a refined mesh, with very small size.
Luciano JacintoParticipantThank you very much for the update. I’ve just tested the method addThermalDistLoad() in several beams (doblefixed, fixedsupported and continuous) and everything worked as expected, both uniform gradient and linear gradient. Congratulations!
Luciano JacintoParticipantIn the case of uniform gradient the result given by NextFEM (compression) is obviously correct. The doubt is only about linear gradient.
Luciano JacintoParticipantThanks. This time the solver ran the model without problems and the results were as expected.
Luciano JacintoParticipantThank you very much!
Luciano JacintoParticipantCongratulations for the 2.2.0.5 release. I made some tests, and everything seems work perfectly. I also notice that it was made an improvement in API for Python. Now we can specify several load values and the corresponding positions:
nf.addBeamLoad(
elem = e1,
values = [0, 12, 12, 0],
positions = [0.0, 1.0, 4.0, 5.0],
direction = 2,
loadcase = ‘lc4’,
local = True,
)Is there a change log so that we can look for the improvements in each release?
Thanks for this very nice program.Luciano JacintoParticipantThak you very much. I will look forward for the new release.
Luciano JacintoParticipantSorry, but the problem with nonuniform loads on beams persists. For a simple supported beam with a span of 5 m and a triangular load, 0 at the beginning and 12 kN/m at the end, the moment at the midspan is 18.75 kNm, but the program gives a strange result (a negative value!). Please verify this. Thanks.
Luciano JacintoParticipantMany thanks for your quick reply. The problem is solved. I will continue to test NextFEM, which seems to be a very interesting program: simple and powerful.

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