Problem 3. Solid circular shafts made of titanium 6Al-4V (annealed) are subjected in service to bending, with a moment M = 6.0kNm. Half-circular surface cracks, as in Figure below, may exist in the part. From nondestructive inspection, it is expected that no cracks larger than a = 5 mm are present. (a) What shaft diameter is required to resist yielding with a safety factor of 2.0 if no crack is present? (b) For an inspection-size crack, what shaft diameter is required to resist brittle fracture with a safety factor of 3.0? (c) What shaft diameter should actually be used? (a) P 111 2b 2t M P M (b) P M K = FS SS (tension, P) SS (bending, M) (c) (d) Case St Sb F for small a Limits for 10% on F P 2 a a (a) = 0.637