- posted
16 years ago

Can anyone help me with an area moment of inertia problem that i have?

I'm idealising a cross-section of an aircraft longeron and one of the

flange of the longeron is inclined at at an angle. While there is a

formula to find the area moment of inertia of a inclined beam (I'm

idealise that inclined flange into an inclined beam), there is nothing

about which distance to use when i have to use parallel axis theorem to

find the total area moment of interia for the whole cross-section.

A fellow engineer told me to use the distance from the centroid of the

inclined beam e.g. treat it like a normal vertical or horizontal

element, but it is correct? I think that for one axis, the assumption

is approximately correct but not correct for the other axis. Its a bit

hard to describe my problem in words so if you need the diagram to

understand my problem, please drop me an email at

arrow snipped-for-privacy@hotmail.com.

Thanks a million!

Ethan Ng