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Elliptical Water Tight Container?


(John Griffiths) #1

I am interested in designing an elliptical WTC. I am unsure if the elliptical shape would mean greater pressure on the flatter sides leading to implosion at much lesser depth than a comparable wall thickness round WTC… if anybody understands the issue, I would certainly welcome input.
thanks

John


(Jacob) #2

Eggs are pretty strong! The pressure outside the WTC remains constant regardless of the shape, but what is important is the structural advantage of the arch shape to distribute the stress evenly. I’m not sure if a perfect circle is technically stronger than an ellipse.


#3

Presuming that you’re talking about an elliptical cross-section container, it will implode at a lesser depth than an equal wall thickness circular cross-section container.

There’s a working of the equations for the stress at any point in that elliptical cross-section container here:
http://www-eng.lbl.gov/~shuman/NEXT/MATERIALS&COMPONENTS/Pressure_vessels/ovality_stress_tubes.pdf

And a finite element analysis example here (showing higher stresses):


(John Griffiths) #4

Hi Jacob

thanks for the response. I have more or less settled on the shape in the attached jpeg. the motors are mounted in the centre cavity so the walls of the cavity should provide extra buttressing. I will run the 8 motor softwware to give me a great deal of pitch. at least that is the plan. dont hesitate to let me know if you see any obvious flaws in the concept.

kind regards

John Griffiths