Question

PROBLEM 4: Calculate the diameter D of the rotating shaft, supported on each end by a radial bearing, to obtain infinite life with a safety factor of 1.2. The shaft is machined from AISI 1040 HR steel, and is subject to a bending moment caused by a static force F-4 KN. The radius r is 0.05D. The length of the shaft L 0.5 m. The shaft rotates at in 1 ㄧㄒㄨ D. In 1000 RPM. Assume full notch sensitivity q = 1. Hand in: Diameter D of the shaft L/2 Figure 4: Rotating stepped shaft with fillet

Answer 1

"Given data is Force F = -4 k N radius (r) = 0 . 05 D length or the shalt (L) = 0 . 5 m shalt rotates at n = 1000 R P M notch sensitivity (q) = 1 \r\n the bending stress (sigma) = 32 M/pi d^3 where d = D - 2 r = D - 2 times 0 . 05 D Therefore d = 0 . 9 D Rightarrow = 32 times 250/pi d^3 = 2546 . 479089/d^3 as the shalt is rotating (it is completely reserved loading so mean stress = 0 and amplitude stress = applies stress) 6_max = -6_min 6_max = 0 6 a = sigma = 2546 . 479089/d^3 For initiate lite 6 a/s e = 1/F. s \r\n where s_e = endurance limit stress s_e = 0 . 5 S_w K_a K_b K_c K_d For A