Question

131- (3 marks) Figure below shows a bolted joint subjected to an external force P that fluctuates from 0 to 7 kips. The steel bolt specification is 5/8"-11 UNC, SAE grade 5 material with rolled threads. The clamped members are steel of length 1.25 in each (with a total length of 2.5 in). Plain wide washers are utilized at both ends of the bolt. [a]. Using the Goodman line, determine the factor of safety guarding against fatigue failure for the two cases, (i) no pre-load is applied to the joint, (ii) a recommended pre-load is applied to the joint assuming a non-permanent connection. For the calculation of member stiffness km, neglect the frusta associated with the washers at the two ends of the bolt. For this calculation, assume that no stress concentration factor exists in the problem [b]. Check the joint for maximum stress in the bolt not exceeding the bolt proof stress under static loading. Again, for this calculation, assume that no stress concentration factor exists in the problem P , steel hult, -n UNC 2.5 [c]. Repeat [a] by considering stress concentration factor in fatigue in the bolt threads. Repeat [b)] with theoretical stress concentration factor in the bolt threads to be the same as in fatigue (i.e notch sensitivity, 1.

the material is steel. hence the ultimate strength can be found.

Answer 1

A七一0, 2260 locult a s- 千 トS O.226o -'" Rb-0086 드 Akona 니 千

5c(81.2-765) + 100% 14,9

So (81.2-76r) +100% 4.8 2 fuょ.PA2) , e22 ) fve o 26o o 22 So 6 4.8 pci