Name of the College : P.E.S College of Engineering
University : Visvesvaraya Technological University
Department : Automobile Engineering
Subject Code/Name : P08AU63/Design of Machine Elements – II
Year : 2010-11
Degree : B.E
Sem : VI
Website : pescemandya.org
Document Type : Model Question Paper
Download Model/Sample Question Paper : https://www.pdfquestion.in/uploads/pescemandya.org/4676-qp.pdf
Design of Machine Elements-II :
SIXTH SEMESTER B. E. – SEE – FOR THE ACADEMIC YEAR: 2010-11
Course with code: Design of Machine Elements – II (P08AU63)
Credits: 04
Related : P.E.S College of Engineering P08AU64 CAD/CAM/CAE B.E Model Question Paper : www.pdfquestion.in/4677.html
Time: 3 hrs Max.
Marks: 100
Note:
1) Answer any five full questions choosing at least two questions from each part.
2) Use of data hand book is permitted
3) Missing or wrongly printed data, if any, may be assumed suitably and stated clearly
Part- A :
1. a) What are the assumptions made to derive the equation s = Ae (Rn y) what are the differences between simple beam and curved beam. (6 Marks)
b) A curved beam with a circular central line has trapezoidal cross section and it is subjected to pure bending in its plane of symmetry. The face 100mm is the concave side of the beam and is 100mm from the centre of curvature and thee load line.
If the depth of the trapezoid is 100mm, find the proper value of the other parallel face to the concave side to make extreme fibre stress in tension and compression numerically equal. (14 Marks)
2. a) A flat circular plate is used to close the flanged end of a pressure vessel of internal diameter of 300 mm. The vessel carries a fluid at a pressure of 2.5 N/mm2 . A soft copper asbestos gasket is used to make the joint leak proof.
Eight bolts are used to fasten cover plate on to the pressure vessel. Selecting carbon steel C30 as material for the bolt, determine the size of the bolts. (8 Marks)
b) Design a shrink fit joint to join two barrels of diameters 50mm X 100mm and 100mm X 150mm , maximum tangential stress in the components due to shrink fitting must be limited to 80 N/mm2 .
The material of the barrels has a modulus of elasticity of 0.211X 106 N/mm2 and a poisson’s ratio of 0.28. Also determine the axial force required to disengage the joint and the maximum power that can be transmitted at a rated speed of 1000 rpm. (14Marks)
3. a) Explain the following:
i) Surge in springs
ii) Equalised stresses in leaf springs. (7 Marks)
b) A helical valve spring is to be designed for opearing load range of 100N to 150N; 100N when valve is closed, 150N when valve is open. The deflection of the spring valve lift in the above load range is to be 8mm. Assuming severe service and C=10 design the spring completely. (13 Marks)
4. a) Distinguish between
i) a clutch and brake
ii) a simple and a differential band brake (4 Marks)
b) In a disc clutch the axial force is 4500N. The inner radius of contact is 50mm and the outside radius is 100mm. Assuming uniform wear, determine i) maximum pressure ii) minimum pressure iii) average pressure and iv) draw pressure distribution. (6 Marks)
c) A differential band brake is operated by a lever length 500mm. The brake drum has a diameter of 500mm and the maximum torque on the drum is 1000N-M. The band brake embraces 2/3rd of the circumference.
One end of the band is attached to a pin 80mm from the fulcrum and on the side of the force acting and the other end is attached to pin 100mm on the other side of the fulcrum.
If the band brake is lined with asbestos fabric having a coefficient of friction 0.3, find the least operating force required. (10 Marks)
Part- B :
5. a) Explain the classification of gears and their applications. (6 Marks)
b) A reciprocating compressor is to be connected to an electric motor with the help of spur gears. The distance between the shafts is to be 500mm. the speed of the electric motor is 900 r.p.m. and the speed of the compressor shaft is desired to be 200 r.p.m.
The torque to be transmitted is 5000 N-m. Taking starting torque as 25% more than the normal torque, determine i) Module and face width of the gears using 20 degrees stub teeth, and ii) Number if teeth and pitch circle diameter of each gear. Assume suitable values of velocity factor and Lewise factor. (14 Marks)
6. A pair of carefully cut helical gears for a turbine has a transmission ration of 10%. The teeth are 200 stub involute in the normal plane. Pinion has 25 teeth and rotates at 5000 rpm
. Material for pinion and gear is 0.4% carbon steel untreated with allowable static stress of 69.66 MPa. Helix angle=300. Power transmitted = 90 kW. Service factor = 1.25. Wear and lubrication factor = 1.25. Determine the module in normal plane and face width of the gears. Suggesdt suitable surface hardness for the gear pair. (20 Marks)
7.a) Explain the thermal rating on warm gear. (6 Marks)
b) A pair of cast iron Bevel gears connected two shafts at right angles. The pitch diameters of the pinion and gears are 80mm and 100 mm respectively. The tooth profile of the gears are of 14 ½ composite form. The allowable static stress for both the gears is 55 N/mm2.
If the pinion transmits 2.75 KW at 1100 r.p.m, find the module and number of teeth on each gear from the stand point of strength and check the design from the stand point of wear. The surface endurance limit as 6.30 N/mm2 and E=84KN/mm2 for CI. (14 Marks)
8. a) Explain the following:
i) Bearing characteristics number
ii) Bearing modules
b) A full journal bearing of 60mm diameter and 120mm long has a bearing pressure of 105 N/mm2. The speed of the journal is 900 rpm and the ratio of journal diameter to the diametral clearance is 1000.
The bearing is lubricated with oil whose absolute viscosity at the operating temperature is 350C., Find
i) the amount of artificial cooling required and
ii) the mass of the lubricating oil required, if the difference between the outlet and inlet temperature is 100C.Take specific heat of oil as 1850J/Kg/0 C. (12 Marks)