dome stresses

hi there,

for understanding the karamba shell components i investigate load on a simple dome (half a sphere).

i want to figure out where to place tension elements (like tension cables or fibres)

one would expect to put them into the lower part of the dome ( just self weight for simplicity)

http://shells.princeton.edu/images/BFigure8.png

i have problem to understand the renderings of the shellView component.

could someone explain difference between princ. stress 1/2 and why stress is also displayed in the top section of the dome (princ.stress 1 plot)

maybe because its not a rotated catenary ?

is it also possible to get out vectors of the shellView component.

thank you !

Attachments:

dome karamba.gh, 28 KB

Replies to This Discussion

Permalink Reply by Karamba3D on April 20, 2014 at 11:35am

Hi Pyrit,

the principal stresses are the minimum and maximum normal in-plane stresses in a point of a shell structure.

Why should there be no stress in the top section of the shell?

Use the 'Principal Stress Directions on Shells'-component to get vectors as result.

Best,

Clemens

Permalink Reply by pyrit on April 21, 2014 at 11:13am

ok thanks, stress is for tensile and compressional forces...

Permalink Reply by pyrit on April 25, 2014 at 2:58am

So one more question,

if i want to strenghten a shell structure with rod like elements ( i would like to investigate reed )

i should use the principal stressLinesOnShells component and prinicpalForceDirectionsOnShells component to figure out their best location. for the most simple cases its clear what compression and what tensile is but is there exact way to tell (N1 or N2)

thy !

Permalink Reply by Karamba3D on April 27, 2014 at 11:19pm

The principal stress lines on shells indicate the best orientation for reinforcing elements.

If bending moments are small you could use the directions and values of the first principal in-plane normal forces: the former is returned by the 'PrincipalForceDir'-component, the latter via the 'Shell Forces'-component.

Best,

Clemens

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