Wind Load Inertia

The moment of inertia depends on the mass distribution and dimensions of a body. It has nothing to do with wind. Do you mean torque?

yeah, I am calculating torque.

may be I addressed it in a wrong way, It is Inertia due to wind load.

Thanks

- NTR

I think you are confusing pressure, force, torque, moment, inertia, and moment of inertia (which is somewhat different from its constituent terms).

sorry, if it's confusing.

my intention is to rotate an assembly of solar panels. I have found the MMI of the structure, which will help me to arrive at torque. but, the effect of wind has to be considered in concluding the final torque required to rotate the assembly.

I hope, it's bit clear now.

Thanks,

- NTR

Make the pivot point be at the center, and as near as possible to the plane, of the panel structure. Then except for wind speed variations from one side of the panel to the other, it will be nearly balanced.

Thank you,

The angular acceleration will be so small (or only needs to be so small) that the torque required to accelerate (which is where the moment of inertia comes in) will be negligible compared with the torque to move against wind pressure. BUT there will be a torque required to move against the wind pressure, and torque required to move any unbalanced load - neither having anything to do with moment of inertia.

Depends which way the wind is blowing.

Summarizing.

For rotating the rig, you have the inertia of the mass plus any wind resistance. I assume that the rotation is slow, even when moving to the morning position. Wind force or resistance is proportional to velocity squared. If you walk at 5MPH through still air, you feel minimum resistance, will the outer edge of the sail be moving faster than that? The inner, close to the pivot, will be almost still.

A blowing wind is something else, it could put a force all across the rig. For that, you need the design (fifty year?) wind for the area. You may have to use code prescribed wind speeds.

http://www.wikihow.com/Calculate-Wind-Load Note that for some angles, a flat plate will generate more lift force than when it is perpendicular to the wind, so don't take the perpendicular as your defining value.

A nice technical dissertation with real life figures, not just calculations. http://www.iawe.org/Proceedings/BBAA7/X.Ortiz.pdf

I think others have dealt with your problem, but if the equation does not satisfy dimensional analysis it cannot be correct.

The equation has the correct dimensions for torque (often denoted by J). Nothing to do with moment of inertia.

OK, I didn't know what J was (he didn't say), just took his word for it that it does not satisfy dimensional analysis!

I wasn't complaining about your post .