The factor that does not affect the stress of a shaft is Shaft Length. This is because stress due to torque is determined by shaft material, shaft diameter, and the torque applied, which are all related to the shear stress formula that does not include shaft length.
The factor that does not affect the stress of a shaft is D) Shaft Length. When evaluating the stress within a shaft due to torque, the primary considerations are the shaft material, shaft diameter, and the torque applied. These factors directly relate to the shear stress formula τ = Tc/J, where τ is the shear stress, T is the torque, c is the outer radius, and J is the polar moment of inertia for the shaft cross-section. The shaft length does not enter into this equation as it does not affect the distribution of stress along the cross-section of a shaft. Hence, changes in shaft length will not change the stress experienced by the shaft.