Friday, November 13, 2015

AT6302 Mechanics of Machines Nov Dec 2015 Important Questions

Are you looking for AT6302 Mechanics of Machines important questions Nov Dec 2015 ? We are constantly updating all important questions, previous years papers, lecture notes, question banks of AT6302 Mechanics of Machines . You will here find an important question paper of AT6302 Mechanics of Machines in Anna University Chennai. This is automobile engineering subject taught in B.E Aeronautical Engineering as one of the allied subject. It comes under the syllabus of R-2013 of 03rd Semester. Look more details below and find your question paper of AT6302 Mechanics of Machines.

Anna University Chennai
Department of B.E. Aeronautical Engineering
(A subject of Automobile Engineering)
Third Semester
AT6302 Mechanics of Machines
(Regulation-2013)
Exam Date: 16th November 2015.
Also see the exam time table of B.E Aeronautical Engineering Nov Dec 2015 here

Unit 1:

1. ABCD is a 4 bar chain with link AD fixed. The lengths of the links are AB = 5.25 cm. BC = 17.5 cm. CD =11.3 cm and DA = 20 cm. The crank AB makes 180 rpm. Find acceleration of C and the angular acceleration of BC and CDwhen angle BAD is 15 degree. And B and C lie on opposite sides of AD.

2. Sketch and explain any two inversions of a double slider crank chain.

3. Explain any 3 inversion of single slider mechanism. Determine the degrees of freedom (mobility) of the 3 bar, 4 bar and 5 bar mechanism.

4. Draw the profile of cam which raises a valve with SHM through 3 cm in 1/3 revolution keep it fully raised through 1/12 revolution and it is closed in next 13 revolution with SHM. The valve remains closed during the rest of the revolution. The diameter of the roller is 1 cm and the minimum radius of the cam is 2 cm, the axis of the valve rod is offset by 1 cm from the axis of cam shaft.

5. A cam rotating clockwise at a uniform speed of 200 rpm is required to move a roller follower with a uniform and equal acceleration and retardation on both the outward and return strokes. The angle of ascent the angle of dwell (between ascent and descent) and the angle of descent is 120°. 60". and 90° respectively. The follower dwells for the rest of cam rotation. The least radius of the cam is 50 mm. the lift of the follower is 25 mm and the diameter of the roller is 10 mm. Draw the cam profile and
find the maximum velocity and acceleration of the follower during the out-stroke.

Unit 2:

1. State and prove law of gearing. A sun wheel of 28 teeth is in mesh with a planet of 18 teeth and both are held in arm. The planet wheel is in contact with an internal wheel of 64 teeth which is coaxial with the sun wheel. Sketch the arrangement of the gears and compute the angular velocity ratio between arm and the internal wheel if sun wheel is fixed.

2. A pair of involute spur gears with 16" pressure angle and pitch of module 6 mm is in mesh. The number of teeth in pinion is 16 and its rotational speed is 240 rpm. The gear ratio is 1.75. in order to avoid the interference. determine (1) addenda on pinion and wheel (2) length of path of contact (3) maximum velocity of sliding on either side of pitch point.

3. Two involute gears of 20° pressure angle are in mesh. The number of teeth on pinion is 20 and the gear ratio is 2. If the pitch expressed in module is 5 mm. and the pitch line speed is 1.2 m/s. determine the angle turned through by pinion. when one pair of teeth is in mesh. Also calculate the maximum velocity of sliding. Take addendum as one module.

4. In a epicyclic gear train an arm carries two gears A and 3 having 40 and 60 teeth. if arm rotates at 200 rpm in clockwise direction about the centre of gear A which is fixed makes 300 rpm in the anticlockwise direction. what will be the speed of gear B.

5. Tow involute gears of 20° pressure angle are in mesh. The number of teeth on pinion is 20 and the gear ratio is 2. If the pitch expressed in module is 5 mm. and the pitch line speed is 1.2 m/s, determine the angle turned through by pinion. when one pair of teeth is in mesh. Also calculate the maximum velocity of sliding. Take addendum as one module.

Unit 3:

1. A multiplate clutch has three pairs of contact surfaces. The outer and inner radii of the contact surfaces are 100 mm and 50 mm respectively. The axial spring force is limited to lkN. Assuming uniform wear. find the power transmitted at 1500 rpm. Take u= 0.35

2. A V-belt drive consists of three V belts in parallel on grooved pulleys of the same size. The angle of groove is 30 degree and the co-efficient of friction is 0.12. The cross sectional area of each belt is 750 mm^2 and the permissible safe stress in the material is 7 Mpa. Calculate the power that can be transmitted between two pulleys 400 mm in diameter rotating at 960 rpm. (10 marks) (ii). Derive the condition for maximum power transmission in the belt drives (6 marks)

3. An open belt running over two pulleys 240 mm and 600 mm diameter connects two parallel shafts 3 metres apart and transmits 4 kw from the smaller pulley that rotates at 300 mm. Coefficient of friction between the belt and the pulley is 0.3 and the safe working tension is ION per mm width. Determine : 1. minimum width of the belt. 2. initial belt tension. and 3. length of the belt required.

4. A shaft running at 500 rpm carries a pulley 100 cm dia which drives another pulley in the same direction with a speed reduction of 2:1 by means of ropes. The drive transmits 187 kw. Angle of groove is 40 degree. The distance between pulley centres is 200 cm. The coefficient of frictions is 0.2. The mass of the rope is 0.12 kg/m and allowable stress of 175 N/cm^2. It is recommended that initial tension in the rope should not exceed 800 N. Find the no. of ropes requires and rope dia. Calculate the length of rope also.

5. A single plate clutch effective on both sides is required to transmit 25 kw at 3000 rpm. Determine the outer and inner radi of frictional surface if the coefficient of friction is 0.255 the ratio is radii is 1.25 and the max. pressure is not exceed 0.1 N/mm^2. Also determine the axial load.

Unit 4:

1. For reciprocating engine. derive the expression for 
(i) Velocity and acceleration of the piston (16 marks)
(ii) Angular velocity and angular acceleration of the connecting rod (16)

2. (i) Deduce the expression for the inertia force in the reciprocating force neglecting the weight of the connecting rod. (8)
(ii) A vertical petrol engine with cylinder of 150 mm diameter and 200 mm strokes has a connecting rod of 350 mm long. The mass is 1.6 kg and the engine speed is 1800 rpm. On the expansion stroke with crank angle 30 degree from TDC. the gas pressure is 750 KPa. Determine the net thrust on the piston.

3. The length of crank and connecting rod of a horizontal reciprocating engine are 100 mm and 500 mm respectively. The crank is rotating at 400 rpm.When the crank has turned 30 degree from the IDC, find analytically
1.Velocity of piston
2. Acceleration of piston
3. Angular velocity of connecting rod
4. Angular acceleration of connecting rod. (16)

4. The turning moment diagram for a petrol engine is drawn to a scale of 1 mm to 6N-9-9 m and the horizontal scale of 1 mm to 1". The turning moment repeat itself after every half revolution of the engine. The area above and below the mean torque line are 305, 710, 50, 350, 980 and 275 mm^2. The mass of rotating parts is 40 kg at a radius of gyration of 140 mm. Calculate the coefficient of fluctuation of speed if the mean speed is 1500 rpm. (16)

Unit 5:

1. The spacing of the 4-cylinders A, B, C and D of a vertical in-line engine is 650 mm, 500 mm and 650 mm. The reciprocating masses of the inner cylinders B and C are 80 kg and their cranks are at 60 degree to one another. The stroke is 325 mm and connecting rods are 600 mm long. Find the magnitude of the reciprocating masses for the outer cylinders A and D and the relative angular position of all the cranks if primary forces and couples are to be balanced. What is the maximum
unbalanced secondary force when the speed of engines 375 rpm.

2. A.B. C and D are four masses carried by a rotating shaft at radii 100 mm. 125 mm. 200 mm and 150 mm respectively. The planes in which the masses revolve are spaced 600 mm apart and the masses of B, C, and D are 10 kg, 5 kg and 4 kg respectively. Find the required mass A and relative angular setting of the four masses so that the shalt be in complete balance.

3. A twin cylinder uncoupled locomotive has its cylinders 60 cm apart and balanced masses are 60 deg apart the planes being symmetrically placed about the centre line. For each cylinder the revolving masses are 300 kg at crank pin radius of 32 cm and reciprocating parts are 285 kg. All the revolving and 2/3rd of reciprocating parts are balanced. The driving wheels are 1.8 m dia. When the engine runs at 60 kmph. Find the swaying couple. variation in tractive effort and hammer blow and the distance centre line of wheels is 1.5 m. (AU May/June 2009)

4. Two equal masses of weight 5000 N and radii of gyration 375 mm are keyed to the opposite ends of shaft 600 mm long. The shaft is 100 mm in diameter for the first 250 mm, 175 mm in diameter and 150 mm for the rest. Find the frequency of torsional vibration and the position of the node along the length of the shaft. Take modulus of rigidity of the shaft material is 30 GN/m^2

5. A machine of mass 75 kg is mounted on springs of stiffness 1200 KN/m and with as assumed damping factor of 0.2. A piston within the machine of mass 2 kg has a reciprocating motion with a stroke of 80 mm and a speed of 3000 cycle/min. Assuming the motion to be simple harmonic. find the amplitude of motion of machine. its phase angle with respect to the exciting force. the phase angle of transmitted force with respect to the exciting force.

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