4. An extruded bar of aluminum alloy has the cross section shown in Fig. 4. A 1-meter length of this bar is used as a cantilever beam. A concentrated load P = 1.25 kN is applied at the free end and makes an angle of a = 10 degree with the y-axis passing through the centroid. The view in Fig. 3 is from the free end toward the fixed end of the beam. a) Determine the orientation of the neutral axis. What locations potentially have maximum stress? b) Determine the maximum tensile and compressive stresses in the beam. Note: Neglect torsional effect. (Ans I₂ = 184,333 mm, I, 189,333 mm, Izy = 66,000 mm, 0,max = 180 MPa and oc,max = 145.5 MPa) P y I 1 m P X Z 10 mm- 40 mm Fig. 4 y 30 mm 2 (0,0) α 50 mm 10 mm + Ţi 10 mm

A plane element removed from a thin-walled cylindrical shell loaded in torsion is subject to the shearing stresses shown in Fig. 3-20. Determine the principal stresses existing in this element and the directions of the planes on which they occur. Ans. 50 MPa at 45° 50 MPa 50 MPa 50 MPa 50 MPa

A hollow aluminum box beam has the square cross- section shown in the figure. Calculate the maximum and minimum shear stresses max and min in the webs of beam due to a shear force V = 125 kN.