Max Load before square tube deforms

[raionz]

My boss just told me to get him this today and the last time I took a mechanic class pluto was still a planet.

See diagram attached.

Both bulkhead A and arm are made of aluminum T6061 hollow tubes.
Arm is at center of A.

Assuming that arm will never break off from A, will the current load deform A? I vaguely remember max torsional moments is what I'm looking for but that doesn't take into account material strength.

Shear stress = load + weight of arm.

t=0.25"
b=6"

If max torsional moment is = (2/9) (tau max) (b^3)
tau max = 0.27 (V/t)[b^3-(b-2t)^3] / [b^4 - (b-2t)^4]

V = transverse shear force
is V = shear stress?

Where does material property come in? Please help. Thanks

 

[Achy47]

Dear forum post author,

Thank you for sharing your question and providing the diagram. Based on the information provided, it seems that you are trying to determine the maximum torsional moment on bulkhead A due to the weight of the arm. You are correct in considering the material strength of the aluminum T6061 in this calculation.

To calculate the maximum torsional moment, you will need to determine the transverse shear force (V) acting on the arm. This can be calculated by taking the shear stress (τ) and multiplying it by the cross-sectional area of the arm. In this case, the cross-sectional area would be the area of a hollow tube with a thickness (t) of 0.25" and a width (b) of 6".

Once you have determined the transverse shear force, you can use the equation you provided to calculate the maximum torsional moment. This equation takes into account the material strength by including the shear stress (τ) in the calculation.

It is important to note that the maximum torsional moment calculation assumes that the arm will never break off from bulkhead A. If there is a possibility of the arm breaking off, additional factors such as bending moments and stress concentrations would need to be considered in the analysis.

I hope this helps in your calculations. If you need further assistance, I recommend consulting with a structural engineer or referring to engineering resources for more detailed information. Best of luck with your project.