stiffened cylinder under bending moement
stiffened cylinder under bending moement
(OP)
Hi,
I have devlop the program for the stiffened cylinder under buckling. Now i want to add stresses due to bending moment in it using the relation stress: SIGMA= My/I. So that i could add it in the stresses develop in due to axial compression. here I=Icyl+Istrnger+Iring
The question is how to calculate the y in section modulus(I/y). I know the 'Istrn and Iring' for stringer and ring (Channel) at thier centroid, does the y simply the distance between the outside edge of the flange from the centroid?
Do i need to use parallel axis method to transform 'Istrn and Iring' calculated at stiffer centroid to shift it to cylinder axis?
Really need help.
I have devlop the program for the stiffened cylinder under buckling. Now i want to add stresses due to bending moment in it using the relation stress: SIGMA= My/I. So that i could add it in the stresses develop in due to axial compression. here I=Icyl+Istrnger+Iring
The question is how to calculate the y in section modulus(I/y). I know the 'Istrn and Iring' for stringer and ring (Channel) at thier centroid, does the y simply the distance between the outside edge of the flange from the centroid?
Do i need to use parallel axis method to transform 'Istrn and Iring' calculated at stiffer centroid to shift it to cylinder axis?
Really need help.






RE: stiffened cylinder under bending moement
corus
http://www.corusresearch.com
RE: stiffened cylinder under bending moement
You have a circular cylinder with longitudinal stiffeners.
This cylinder is loaded with axial compression and longitudinal bending moment. Like a beam-column.
If that is the case then the "y" is the distance from the cross-section's center of gravity to the point you are interested in finding the stress. In the expression
stress = My/I, I is for the entire cross-section as stated in the parallel-axis theorem( Ixx = Io +Ad^2).
Assuming this is a symetrical section, then if you want the stress in the shell, then "y" is the shell radius. If you want the stress in the stiffener, then "y" is the distance from the entire section's C.G. to the outer edge of the stiffener.
RE: stiffened cylinder under bending moement
What i understand from your answer, is that for symmetrical case (as that of stiffened cylinder), y=Radius of cylinder for thin cylinder and y=distance from center of cylinder to outer edge of flange for stiffner. is it true?
Also, i have 'I' for stiffners at their centroid, should i use it or transform it to cylinder longitudinal axis using parallel axis theorm.
RE: stiffened cylinder under bending moement
As I said above, "I" should be for the entire cross-section
I(entire section)= I(cyl.)+I(stiff.) +Ad^2(cyl.)+Ad^2(stiff)
RE: stiffened cylinder under bending moement
in equation
I(entire section)= I(cyl.)+I(stiff.) +Ad^2(cyl.)+Ad^2(stiff)
Do i need to use Ad^2(cyl.), since I(cyld)=(PI/64)*(Dou^4-Din^4), give I at its center.
RE: stiffened cylinder under bending moement
RE: stiffened cylinder under bending moement
I am not sure whether I got you. But to avoid buckling, you provide circumferencial stiffeners which are useless in bending.
For bending, you add longitudinal stiffeners. But these stiffeners don't stop buckling. Correct me if I am wrong.