Section A
Q1.
(a) What are meant by killed steels and rimmed steels? Explain the characteristics of these steels. Enlist its applications.
(b) A flat belt transmits 10 kW power at a speed of 5 \text m/s. The mass of the belt is 1.5 \text kg/m and the angle of lap at smaller pulley is 200°. The coefficient of friction between the belt and the pulley is 0.30. Determine the initial tension in the belt.
(c) Compare between involute and cycloidal gear tooth profiles. List the important properties of a good material for sliding contact bearing.
(d) A compound bar is constructed from three bars 50 mm wide by 12 mm thick fastened together to form a bar 50 mm wide by 36 mm thick. The middle bar is of aluminium alloy for which E = 70 × 109 N/m2 and the outside bars are of brass with E = 100 × 109 N/m2. If the bars are initially fastened at 18 °C and the temperature of the whole assembly is then raised to 50 °C, determine the stresses set up in the brass and the aluminium alloy. Take the coefficient of expansion of the brass (α_B) and the aluminium alloy (α_A) as follows : α_B = 18 × 10-6 per °C and α_A = 22 × 10-6 per °C
(e) State the difference between elastic and plastic deformation. Explain each in detail.