14. A steel shaft is subjected to completely reversed bending moment of 800 N-m and a cyclic twisting moment of 500 N-m which varies over a range of ± 40%. Determine the diameter of shaft if a reduction factor of 1.2 is applied to the variable component of bending stress and shearing stress. Assume (a) that the maximum bending and shearing stresses are in phase; (b) that the tensile yield point is the limiting stress for steady state component; (c) that the maximum shear strength theory can be applied; and (d) that the Goodman relation is valid. Take the following material properties: Yield strength = 500 MPa ; Ultimate strength = 800 MPa ; Endurance limit =+ 400 MPa. [Ans. 40 mın]

An SAE3140 OQT1300 steel  shaft with a circular cross section of  1.5 in  diamater is to be machined and subjected to a repeated bending stress. What is the type of stress factor for this design ?   Note : Your answer should be a numerical value only. Do not include an explanation.

A cylindrical steel shaft is required to transmit a bending moment of 1000 Nm and a torque of 2200 Nm with a safety factor against yielding of 3. If the steel has a yield stress of 250 MPa, find the minimum permissible diameter for the shaft. Use von Mises’ theory of yielding.

As part of an innovation policy introduced within the company to research into newer design of swings, the R and D department is proposing that work should be carried out on motorized swings. The initial consideration is to use an electric motor to spin the central shaft. For this purpose a hollow shaft of diameter ratio 3:5 is required to transmit 600 kW at 110 rpm, the maximum torque being 12% greater than the mean. The shear stress is not to exceed 60MPa and the twist in a length of 3m is not to exceed 1 Degree (1º). Calculate the minimum outer diameter (D) to satisfy both these conditions. Take G = 80GN/m2

A steel bar having known S_ut (1200 MPa) and S_y (950 MPa) has a fine ground surface. Determine the fatigue strength for bending corresponding to (1) 10^6 or more cycles and (2) 2 ✕ 10^5 cycles.