Determine the resultant internal normal and shear force in the member at (a) section a–a and (b) section b–b, each of which passes through point A. The 500-lb load is applied along the centroidal axis of the member.
From the definition of normal stress, solve for the minimum area required to support a 27-kip load without exceeding a stress of 18 ksi
The cross-sectional area of the aluminum tube is given by
Set this expression equal to the minimum area and solve for the maximum inside diameter d
The outside diameter D, the inside diameter d, and the wall thickness t are related by
Therefore, the minimum wall thickness required for the aluminum tube is