nav
thanks--got it.
its been awhile but yes all that is understood
i can make the calculations, figure the loads, determine the max moment,
check the deflection, shear at the bolts etc.
all i need is the moment of interia and the section modulus (it is the
correct term) for an oval section
i don't generally deal with oval sections and none are listed in any manuals
i have here.
probably just need to search an alum. association reference. as i have alla
the dimensions of the section involved ( both axis, wall thickness)

i am looking for the section properties to understand max loading in a given
situation..
(working backwards)

as in S sub x (required) = M/f(alum.)
S sub x (actual) of a section = ??

whe
I = moment of interia (inches 4th)
S sub x = section modulus (inches 3rd)
M = moment (#-inches)
F sub b = bending stress. (psi)

simple statics really--i'll just pull a couple of books off the shelf and
dust em off.
actually i'll just call one of my engineers in the morning.
in the meantime.........i'm outta here to find a glass of wine and a blonde
thanks
gf.







"Nav" wrote in message
...


gonefishiing wrote:

refresh my memory:
i'm looking for the section modulus for a boom section to understand
allowable bending stress.
sx= bd(squared) ?
but this is for rectangular sections right?
how do you calculate this for an oval section?
gf.


The shape of the section is taken care of by it's moment of inertia.
The bending stress is the bending moment times the distance from the
neutral axis divided by the moment of inertia of the section.

Stress = M Y /I

This is known as the flexure formula.

Cheers