Vertical Support Section

The vertical support is the largest part of the stand and the main support structure for the Brain Box. This makes it important to maximize the strength and minimize the weight of it.

The following chart shows the different size pipes and their cost that were tested for strength against wind force.

OD	Wall Thickness	Weight	Minimum F.O.S.	Approx. Cost/ft
1.50	0.125	5.06	1.16	2.50
1.50	0.063	2.64	1.37	2.75
2.00	0.125	6c.89	2.95	8.56
2.00	0.063	3.56	2.23	4.00

Below is a screen shot of the finite element analysis. We made a simplifying assumption that the wind pressure on the solar panel would be the most significant force acting on the system, and that other forces would be nearly negligible, so in the analysis, there was no force applied to the vertical pipe.

The reason being, that a round cylinder in comparison to a flat plate has a much lower coefficient of drag, and it has significantly less surface area that is orthogonal to the flow of wind around the structure.

The wind loading equations used to calculate the best fit are as follow:
Wind Force, F = P*Ax-section*Cd,
(Cd = drag coefficient (2.0 flat plate, 1.2 cylinder)
Wind Pressure, P = 0.00256*V^2 (v = wind speed in MPH)
Pressure Used was 6.4 psi.

The stock that was the least likely to fail, under these conditions, was the 2.00" OD and 1/8" wall thickness.

Below is the total cost of the stand:

Katie Gallo kgallo@uvm.edu
Tom Lanagan tlanagan@uvm.edu