The rotor shaft of a helicopter (see figure part a) drives the rotor blades that provide the lifting fore and is subjected to a combination of torsion and axial loading (see figure part b). It is known that normal stress stress xy 68 MPa and shear T. - 100 MPa. Using Mohr's circle, determine the following. (a) The stresses acting on an element oriented at a counterclockwise angle 0 22.5 from the x axis (b) Find the maximum tensile stress, maximum com- pressive stress, and maximum shear stress in the shaft. Show all results on sketches of properly oriented elements. y 68 MPa 100 MPa (a) (b) PROB. 7.4-8 (iker canikligil/Shutterstock)