Jawaharlal Nehru Technological University Hyderabad B. Tech III DYNAMICS OF MACHINERY Previous Question Paper (August/September - 2024 - R16)

Define axis of precession.

What is the principle of gyroscope?

Define fluctuation of energy.

Sketch Turning moment diagram for four stroke cycle internal combustion engine.

What is angle of repose?

Differentiate brakes and dynamometers.

Define isochronism.

What is the effect of swaying couple?

What is three rotor systems in a vibrating body?

What is the impact of critical speed on the vibrating systems?

A four-link mechanism with the following dimensions is acted upon by a force 80N at an angle 1500 on the link DC as shown in figure 1. Given AD = 500 mm, AB = 400 mm, BC= 1000 mm, DC = 750mm, DE = 350mm Determine the input torque T on the link AB for the static equilibrium of the mechanism for the given configuration.

A petrol engine 100 mm in diameter and 120 mm stroke has a connecting rod 250 mm long. The piston has a mass of 1 kg and the speed is 1800 rpm. The gas pressure is 0.5 MPa at 30° from top dead centre during the explosion stroke. Find (a) the resultant load in the gudgeon pin, (b) the thrust on the cylinder walls, (c) the speed above which the gudgeon pin load will be reversed, and (d) the crank effort at this position.

The turning moment diagram for a multi-cylinder engine has been drawn to a scale 1 mm = 600 N-m vertically and 1 mm = 3° horizontally. The intercepted areas between the output torque curve and the mean resistance line, taken in order from one end, are as follows: + 52, – 124, + 92, – 140, + 85, – 72 and + 107 mm², when the engine is running at a speed of 600 r.p.m. If the total fluctuation of speed is not to exceed ± 1.5% of the mean, find the necessary mass of the flywheel of radius 0.5 m.

A double shoe brake, as shown in figure 2. Is capable of absorbing a torque of 1400 N-m. The diameter of the brake drum is 350 mm and the angle of contact for each shoe is 100°. If the coefficient of friction between the brake drum and lining is 0.4; find a) The spring force necessary to set the brake; and b) The width of the brake shoes, if the bearing pressure on the lining material is not to exceed 0.3N/mm².

The following data relates to a single cylinder reciprocating engine: Mass of reciprocating engine – 40 kg, Mass of revolving parts - 30 kg at crank radius, speed- 150 rpm, stroke – 350 mm. If 60% of the reciprocating parts and all the revolving parts are to be balanced, determine the a) Balance mass required at a radius of 320 mm b) Unbalanced force when the crank has turned 45° from the top dead centre.

A Proell governor has equal arms of length 300 mm. The upper and lower ends of the arms are pivoted on the axis of the governor. The extension arms of the lower links are each 80 mm long and parallel to the axis when the radii of rotation of the balls are 150 mm and 200 mm. The mass of each ball is 10 kg and the mass of the central load is 100 kg. Determine the range of speed of the governor.

A steel shaft 1.5 m long is 95 mm in diameter for the first 0.6 m of its length, 60 mm in diameter for the next 0.5 m of the length and 50 mm in diameter for the remaining 0.4 m of its length. The shaft carries two flywheels at two ends, the first having a mass of 900 kg and 0.85 m radius of gyration located at the 95 mm diameter end and the second having a mass of 700 kg and 0.55 m radius of gyration located at the other end. Determine the location of the node and the natural frequency of free torsional vibration of the system. The modulus of rigidity of shaft material may be taken as 80 GN/m².