Karamba, Local Stress analysis


I’m trying to analyse a dome (half sphere) in karamba.
I realised “ShellVectResults” give us only principal stress.
Is there a way to found the local stress of my mesh, with the layer position option (Bottom -1; Middle 0; Top 1) ?
(“S-Forces” component doesn’t have the layer position option.)

Thank you for any help

Hi @cc1,
in Karamba3D 1.3.2. there is no component for calculating the stresses.
However one can get the cross section forces in the local x- and y-direction. For a shell of thickness ‘t’ the normal stresses sigma_xx at a distance ‘s’ from the middle surface can be for example calculated like this:
sigma_xx = n_xx/t - m_xx/(t^3/12)*s
Regarding the sign in front of the moment-term: the local axes x,y and z form a right-handed coordinate system. A positive ‘m_xx’ causes a positive rotation about the local y-axis and thus compressin in layers with a positive z-location.

Hi Clements,

I totally agree with your process.
What about implement a new component for the next release?


Hi Marco,
I have put it on my TODO-list.

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It’s great to hear that a local stress component is in the pipeline. In the meantime, would it be correct to think that working out local stresses based on sigma=n/t+6m/t^2 is not applicable to the Analize Nonlinear WIP results?

Hi @r.lorenzo,
the formula should work also in case of large deformation analysis.