STEESS AND DEFORMATION 



13 



35. An engine cylinder is 10 in. inside diameter and carries a steam pressure 

 of 801b./in. 2 Find the number and size of the bolts required for the cylinder 

 head for a working stress in the bolts of 2000 lb./in. 2 



36. Find the required diameter for a short piston rod of hard steel for a piston 

 20 in. in diameter and steam pressure of 125 lb./in. 2 Use factor of safety of 8. 



37. -A rivet 1 in. in diameter connects two wrought-iron plates each g in. thick. 

 Compare the shearing strength of the rivet with the crushing strength of the plates 

 around the rivet hole. 



38. In the United States government tests of rifle-barrel steel it was found that 

 for a certain sample the unit tensile stress at the elastic limit was 71,000 lb./in. 2 , 

 and that the ultimate tensile strength was 118,000 lb./in. 2 What must the factor of 

 safety be in order to bring the working stress within the elastic limit ? 



39. In the United States government tests of concrete cubes made of -Atlas 

 cement in the proportions of 1 part of cement to 3 of sand and 6 of broken stone, 

 the ultimate compressive strength of one specimen was 883 lb./in. 2 , and of another 

 specimen was 3256 lb./in. 2 If the working stress is determined from the ultimate 

 strength of the first specimen by using a factor of safety of 5, what factor of safety 

 must be used to determine the same working stress from the other specimen ? 



40. An elevator cab weighs 3 tons. With a factor of safety of 5, how large 

 must a steel cable be to support the cab ? 



41. A hard-steel punch is used to punch holes in a wrought-iron plate | in. 

 thick. Find the diameter of the smallest hole that can be punched. 



42. A mild-steel plate 10 in. square and ^ in. thick is stretched 0.002 in. in one 

 direction by a certain pull. What pull must be applied at right angles to reduce 

 the first stretch to 0.0014 in. ? 



43. A structural steel tie rod of a bridge is to be 25 ft. long when the bridge is 

 completed. What should its original length be if the maximum stress in it when 

 loaded is 18,000 lb./in. 2 ? 



44. A hard-steel punch is used to punch a circular hole \ in. in diameter in a 

 wrought-iron plate \ in. thick. Find the factor of safety for the punch when in use. 



45. A cast-iron flanged shaft coupling is bolted together with 1-in. wrought- 

 iron bolts, the distance from the axis of each bolt to the axis of the shaft being 6 in. 

 If the shaft transmits a maximum torque of 12,000 ft.-lb., find the number of 

 bolts required. 



46. A steam cylinder of 16 in. inside diameter carries a steam pressure of 

 150 lb./in. 2 Find the proper size for the hard-steel piston rod, and the number of 

 |-in. wrought-iron bolts required to hold on the cylinder head. 



47. A horizontal beam 10 ft. long is suspended at one end by a wrought-iron rod 

 12 ft. long and \ in. in diameter, and at the other end by a copper rod 12 ft. long 

 and 1 in. in diameter. At what point on the beam should a load be placed if the 

 beam is to remain horizontal ; that is, if each rod is to stretch the same amount ? 



48. When a bolt is screwed up by means of a wrench, the tension Tin the bolt in 

 terms of the pull P on the handle of the wrench is found to be given approximately 

 by the empirical formula y _ 75 p 



for a wrench of maximum length of from 15 to 16 times the diameter of the bolt. 

 What is the largest wrench that should be used on a f -in. wrought-iron bolt, and 

 what is the maximum pull that should be exerted on the handle ? 



