Given a cross section of a wing box with $2$ closed section and a open section with

shear modulus G$=25000$N$//$mm$^(2)$ and $10^(8)$N$//$mm$^(2)$ respectively. The section is

subjected to a torque of $100$ kNm and the entire section is $2$ mm in thickness.

Please calculate

a$.$ Rate of twist of the section

b$.$ Maximum shear stress

Now the closed section has been removed and the remaining cross section

becomes symmetric. The section is now subjected to an anticlockwise torque of

$100$ kNm $.$ Calculate the distribution of warping around the cross$-$section. Illustrate

your answer clearly by means of a sketch and insert the principle values of the

warping displacements.

Please use handwriting.