Karamba - user problems

please post here in case of karamba problems !

Replies to This Discussion

Permalink Reply by Aytaç Balci on February 7, 2020 at 5:20am

If I enter the path with or without trailing slash I get errors. It still does not see the files located in there.

Permalink Reply by Karamba3D on February 11, 2020 at 1:18am

Hi, you did not specify a file, but just the folder in the panel

Permalink Reply by Aytaç Balci on February 11, 2020 at 1:25am

Why is the input named Path and not File then? Very confusing. Well, thanks for your answer.

Maybe, something for in future editions? Pointing to path instead of single file?

Permalink Reply by Karamba3D on February 11, 2020 at 1:30am

It is to represent 'File Path'. If you hover over the input you can see this and if you display the full names, this can be seen too.

Permalink Reply by riccardo foschi on February 10, 2020 at 9:43am

Hi all, why changing the mesh density it changes so much the resulting displacement of the mesh?

Permalink Reply by Karamba3D on February 11, 2020 at 1:22am

A course mesh (large mesh sizes) can give you inaccurate results. A general rule of thumb is to reduce the mesh resolution so that the difference in results is very minimal.

Permalink Reply by riccardo foschi on February 11, 2020 at 1:28am

Thanks for the fast answer, so how do I compare two objects properly if the mesh size matter this much? and how do I know what is the correct density of the tessellation? Are there any guidelines to follow?

PS: is Karamba suitable to test solid geometries instead of open meshes or beams and pillars structures?

Permalink Reply by Karamba3D on February 11, 2020 at 1:32am

therefore you need to reduce the mesh size of the karamba mesh to a point where the results do not change anymore. Be careful when doing this as the calculation time can increase dramatically.

Karamba cannot test sold geometries, only shells or beams.

Permalink Reply by riccardo foschi on February 11, 2020 at 1:45am

ok I'll try to make the mesh denser,

about the shell and beams structures, can this be considered as a shell?

it's hollow inside. when Karamba calculate a shell does it add a specific section to each edge? so if I increase the number of edges will it increase the mass of the sistem?

Permalink Reply by Karamba3D on February 11, 2020 at 2:05am

Karamba automatically assigns a thickness (1cm) and steel material to your shell if you do not assign it yourself. Also if you simply take your faces from the surface and convert them into mesh faces, then you have a rather course mesh, and inaccurate results. Simply weaverbird or another tool to increase the density of your mesh. The mass should not increase as the base geometry is the same - just the resolution of the mesh itself.

Permalink Reply by riccardo foschi on February 11, 2020 at 2:37am

Ok I was able to make the results converging by making the mesh denser, thanks for the tips.

However I have noticed that in my case the section of the shell compared to its height is too different.
The fact that I'm applying a vertical load to the shell maybe could be a problem.

(the load is parallel to the central axis) I'm not very familiar with FEA analysis, but I just read online that if the ratio height\base of the mesh section is bigger than 0.5 it should be calculated with solid analysis and not with shell analysis.

Permalink Reply by Karamba3D on February 11, 2020 at 10:58am

Hi Riccardo,

in your case of of a cylinder it is not the ratio between height to base diameter but height to shell thickness which needs to be small for a shell calculation.