The figure shows a cantilever beam loaded by a normal force N = P and a torsion moment Mx = 0.4P a. The thin-walled cross-section is a double symmetric box profile with overall dimensions given in terms of a as shown in the figure. The thickness of the top and bottom flanges is 2t, while the thickness of the side flanges is t. The material is linear elastic with elastic modulus E and shear modulus G = E/2.6.
a) Determine the distribution of the normal stress from N.
b) Determine the shear stress distribution from Mx.
c) Find the largest principal stress σ1 in each of the four flanges.
d) Determine the angle between the largest principal stress component σ1 and the longitudinal axis x, and show the orientation of the principal stresses in a figure.
