Section A
Q1.
(a) Design a set of stepped pulleys to drive a machine from a countershaft that runs at 220 r. p. m. The centre distance between the two sets of pulleys is 2 m. The diameter of the smallest step on the countershaft is 160 mm. The machine is to run at 80 r. , 100 r. and 130 r. , and should be able to rotate in either direction. Find the length of the belt required for both the cases.
(b) What is the chief difference between heat-treatable and non-heat-treatable alloys?
(c) A bar of length L, material density S and modulus of elasticity E is rotating about one end with an angular speed of omega radians per second. Find the maximum stress set up in the bar and its extension due to rotation.
(d) The end of a rod made of mild steel is sliding over the unlubricated surface of hardened tool steel with a load of 100 kg. The hardness of mild steel is 15 HB. What is the distance travelled to produce a wear volume of 1 mm3 by adhesive wear of the mild steel rod?
(e) Give a neat sketch of a unit cell of copper. Indicate Miller indices for its slip plane and slip direction. Why is copper so ductile?