The shaft BCD in the figure has length L and is composed of a homogeneous material with shear modulus G. The bar is fixed between walls at B (x=0) and D (x=L). The shaft has a round cross section, with outer radius changing along the length of the bar as defined by the function:
R(x)=R01+x2L.
A concentrated torque of magnitude Q is applied at the midsection of the bar C (x=L/2) as indicated. Use the Force Method for SI structures taking D as the redundant support to solve this problem.