Result node numbers are not equal to FEM mesh NodeCount.

[MustafaISSA]

Hello everyone,

I import a step file to Freecad to do static simulation, when I run the simulation it gives this error :

CalculiX returned an error due to nonpositive jacobian determinant in at least one element
Use the run button on selected solver to get a better error output.

Do you have an idea for this error?

Thanks.

[NewJoker]

Here you can find some tips regarding this error: https://wiki.freecad.org/FEM_MeshGmshFromShape#Notes

[MustafaISSA]

Thank you for your response, actually, I have tried to increase the mesh elements, and the problem can be solved but it gave not a reasonable answer for displacement. Here is the file you can take a look at.

I have 540 N force applied on the upper surface. The material is Aluminum generic, and I applied the self wight too.
the basement is fixed.

file to send.FCStd

(145.11 KiB) Downloaded 29 times

[Vision78]

Having looked at the model and trying out the simulation, do you mean the 21km displacement?

Id simplify it only to the top beam and if needed making sure the parts are properly attached to eachother in the model, looks like it yeets the whole thing somewhere

[MustafaISSA]

Yes, I have solved it before, it gave a 1.5 mm displacement for the upper part. but I added an extrude to link two parts to each other as shown in the figure below.
I have done the analysis by SolidWorks after modification and there was no problem.

Capture01.JPG (30.41 KiB) Viewed 580 times

[Vision78]

Yes, I have solved it before, it gave a 1.5 mm displacement for the upper part. but I added an extrude to link two parts to each other as shown in the figure below.
I have done the analysis by SolidWorks after modification and there was no problem.

Capture01.JPG

1,5mm looks about right as it is a distributed load, the lid to this part isnt essential for the simulation though and just makes it more complicated than it needs to be.

I probably should switch my elements because in the simulation everything was wonky, it didnt like the hollow thin parts.

[MustafaISSA]

I add this extrude to fix the diagonal part. because it was moving too during the simulation, i tried to fix it by assembly but it gave me overdefined.

the 1.5 mm this answer before adding this extrude

Thanks for the collaboration