The element in the figure is located at the inner edge of a hub that has been press-fitted on a shaft. The normal stress in the radial direction r=50MPa (compressive) and the normal stress in the tangential direction t=70MPa (tensile). There is no shear stress. a. If the hub material has a yield point value of 300MPa, find the factor of safety by maximum distortion energy theory. b. If the hub is made of cast iron with ut=140MPa and uc=400MPa, find the factor of safety by the maximum normal stress theory. The element in the figure is located at the inner edge of a hub that has been press-fitted on a shaft. The normal stress in the radial direction r=50MPa (compressive) and the normal stress in the tangential direction t=70MPa (tensile). There is no shear stress. a. If the hub material has a yield point value of 300MPa, find the factor of safety by maximum distortion energy theory. b. If the hub is made of cast iron with ut=140MPa and uc=400MPa, find the factor of safety by the maximum normal stress theory