DESIGN OF MACHINE ELEMENTS

 

DEPARTMENT OF MECHANICAL ENGINEERING DESIGN OF MACHINE ELEMENTS

PART A

UNIT-1

1. Name atleast five mechanical properties of materials .

2.  What are factors to be considered for the selection of materials for the design of machine elements(

3.  Define factor of safety for ductile and brittle materials

4.  Explain preferred number with an examples(

5.  What is free cutting steel? How it is designated?

6.  How engineering materials are classified

7.  Write composition designated as given below XT 15 Cr 16 Ni 2(Apr 10

 

Unit-2

1. What are the types of shaft?

2. What are the advantages and disadvantages of keys?

3.   What are keys? How are they classified?

4.   What are the requirements of couplings?

5.   Name three types of couplings used in engineering

Unit-3

1.What are the requirements of belt drive

2.Explain the two different belt drives with sketches 3.Explain different types of belts with sketches.

4.Explain different types of belts material. 5.compare flat belt with v-belt

 

1. How bearings are classified?

Unit-4

2.  Write short notes on radial and thrust ball bearing

3.  Explain how ball bearing is designated with an example

4.  Explain the important physical characteristics of a good bearing material

5.  State the advantage of roller contact bearings

 

Unit-5

1.     What is CAD?

2.    What are the benefits of CAD?

3.    What are the disadvantages of CAD?

4.    What are the applications of CAD?

5.    State the various activities of

6.    Compare sequential engineering and concurrent engineering.

7.    What are the benefits/advantages of concurrent engineering

8.    Define transformation?

9.      What are the techniques of geometric modeling?

10.   What are the advantages and disadvantages of solid modeling?

11.   What are the advantage of wire frame modeling

12.  What are the advantage of surface modeling.

13.  What is finite element analysis

14.  State any four advantages of finite element analysis?

PART B

UNIT-1

1.   Design sleeve and cotter joint to transmit a tensile load of 60kN, Assuming that all the parts are made of same material. The permissible stresses are 60N/mm^2 in tension, 120N/mm^2 in Crushing and 75N/mm^2 in shear.

2.   Design a Sleeve and cotter joint to transmit a tensile load of 80kN, Assuming the all part are made of same material the permissible stresses are 62N/mm^2 in tension,125 N/mm^2 in bearing and 78 N/mm^2 in shear.

3.  Design a sleeve and cotter joint to withstand a tensile load of 70kN.All parts are made of same materials. The permissible stresses are 60N/mm^2 in tension,120N/mm^2 in compression and 70N/mm^2 in shear.

4.  Design a sleeve and cotter joint to withstand a tensile load of 60kN. All parts are made of same materials and the permissible stresses in the material are 60N/mm^2 in tension, 125N/mm^2 in crushing and 70N/mm^2 in shear.

5.    Design a knuckle joint to sustain a maximum pull of 80kN.The working stresses of rod material are 75MPa in tension and 70MPa in shear. The permissible shear stress for the pin material is 65MPa.

6.   Design a knuckle joint to take a load of 60kN, assuming that all parts are made of same material. The permissible stresses are 60MPa in tension and 75MPa in compression and 40MPa in shear respectively,

7.   Design a sleeve and cotter joint to withstand a tensile load of 70kN, all parts of the joint are made of same material. The permissible stresses are in 60N/mm^2 in tension, 120N/mm^2 in compression, and 70N/mm^2 in shear.

8.   Design a knuckle joint to take load of 140kN, for the following permissible stress: 75MPa in tension, 140MPa in compression, and 65MPa in shear.

9.  Name the type of steel with its composition designated as X15Cr16 Ni12 or XT15CrNi2

10.  What are the factors to be considered for the selection of materials for the design of machine elements?

11.  Define factor of safety for ductile and brittle materials’.

12.   A Knuckle joint connects two parts of a tie – rod subjected to an axial load of 100 KN. The Ultimate stresses for the material of the joint are 480 N/mm2 in tension and 360 N/mm2 in shear .Design the Joint.

 

UNIT-2

13.   Design the give the complete specification of a protected type flange coupling to transmit a power of 15KW at 240Rpm.The Permissible shear stress for the shaft, bolt and key materials is 35N/mm2, The permissible crushing stress for the bolt and key materials is 60N/mm2 and the permissible shear stress for the flange materials is 15N/mm2.Assume that the maximum torque exceeds the mean torque by 20%.

14.   Design a protective type flange coupling to connect two shafts to transmit 7.5KW at 720 Rpm. The Permissible shear stress for shafts, bolt and key materials is 33N/mm2, Permissible crushing strength for the bolt and key materials of 60N/mm2 and permissible shear stress for CI is 15N/mm2.

15.   Design a protective type of cast iron flange coupling for a steel shaft transmitting 15KW at 200Rpm. The allowable shear stress is 40N/mm2. The working stress in the bolts should not exceed 30N/mm2. Assume that the same material is used for shaft and key. The crushing stress is twice the value of shear stress. The maximum torque is 25% greater than full load torque. The shear stress for cast iron is 14N/mm2. Check your design for Hub, Key, Flange and Bolts.

16.   A rigid flange coupling is to be designed to transmit 20KW at 1000rpm. Allowable shear stress for shaft, key and bolts is 40N/mm2. Allowable crushing stress for key and bolts is 80N/mm2, and Allowable shear stress for flange material is 15N/mm2. Design the coupling

17.   The shaft and flange of marine coupling is to be transmitting 3MW at 100 rpm. The shear stress for shaft and bolts is 60N/mm². The number of bolt is 8. The P. C. D of the bolt is 1.6d. Design the coupling.

 

UNIT-3

17.   The following data refers to a V-belt drive; Power to be transmitted-75KW; Speed of driving wheel- 1440rpm;Speed of driven wheel-400rpm;Diameter of driving wheel-300rpm;Center distance-2.5m;Smaller pulley factor-1.07;Service factor-1.3;Correction factor for length-1.07.Design and give the complete details of the drive.

18.   Design V-belt drive for the following specifications; Power to be transmitted- 75KW, Speed of driving wheel - 1440rpm, Speed of driven wheel - 400rpm, Diameter of driving wheel - 300mm,Center distance - 2500mm, Small pulley factor, kd - 1.14, Service factor, ks -1.3,Correction factor for length kl - 1.07

19.     Design a V-belt drive using manufacture’s data to the following specifications; Power to be transmitted;75KW;Speed of driving pulley;1000rpm;Speed of driven pulley - 300rpm;Diameter of driving pulley - 150mm;Diameter of driven pulley - 500mm;Center distance between pulleys - 925mm;Service -16 hrs/day.

20.     Design a V-belt drive using manufactures data to the following specifications: Power to be transmitted=75KW; Speed of driving wheel=1440rpm; Speed of driven =400rpm; Diameter of driven wheel=300mm; Center distance =2500mm; Service =16hrs/day.

21.    Design a V-belt drive to transmit 15KW to a compressor. The Motor Speed is 1200RPM and the Compressor Pulley runs at 400RPM. Determine the size and numbers of belts.

22.  Design a V-belt drive on Manufacturer’s data to the following Specifications;

Diameter of driven Pulley = 600mm, Diameter of driving Pulley = 200mm, Center distance between Pulleys = 1000mm (approx.),Speed of driven Pulley = 400 rpm ,Speed of driving Pulley = 1200 rpm

,Power transmitted 10KW ,Service –heavy duty = 16 hrs/day.

 

UNIT-4

23.   Design a suitable journal bearing for a centrifugal pump having a following specifications: Load on bearing-13.25kN; Diameter of the journal-80mm; Speed-1440 Rpm; Permissible bearing pressure-0.7 to

1.4 N/mm^2; Ambient temperature-30oC. L/D Ratio-1.6 ; Average temperature of oil-75oC (SAE 40) ; K -

0.273 for heavy construction and well ventilated bearings and ; temp rise -8 oC. Specific heat of oil = 1710 J/Kg o C . Calculate the cooling requirements.

24.   Design a suitable journal bearing for a centrifugal pump having a following specifications: Load on bearing-14kN; Diameter of the journal-80mm; Speed-1440rpm; Bearing characteristic number-30x10^-6 ; Permissible bearing pressure-0.7 to 1.4N/mm^2; Average atmospheric temperature-30*c L/D ratio-2; average temperature of oil-75*c; coefficient of heat dissipation-0.273W/m^2/*c; temp rise -6*c. Calculate the cooling requirements using laches `equations and McKee’s equation for calculating friction Co efficient.

25.   Design a Suitable journal bearing for a centrifugal pump to withstand a load of 60kN.the diameter and the speed of the journal are 150mm and 960 rpm respectively.

26.   Design a Journal bearing for a centrifugal pump from the following data: Load on the journal = 20kN, speed = 900rpm, type of oil used is SAE10 for which the absolute viscosity at 55oc=17centipoise, ambient temp of oil=15.5oc, Max bearing pressure =1.5N/mm^2 .Heat dissipation co efficient =1232 J/s/m^2/oC. Calculate mass of lubricating oil required for artificial cooling, rise of temp of oil is limited to 10o .

27.   Journal bearing is proposed for a centrifugal pump. The diameter of the journal is 150mm and the load on its 40kN and its speed is 900rpm .design and give the complete calculation of the bearing.

29.  Design a Journal bearing for a centrifugal pump from the following data: Load on the journal= 20kN,

Speed = 900rpm

Type of oil used SAE10 Absolute viscosity at 55*c=17cP Amp ion temp of oil=15.5*c Max bearing Press =1.5N/mm^2

Heat dissipation Co Efficient =1232 J/s/m^2/*c     Calculate mass o lubricating oil required for Artificial cooling, if rise of temp of oil is limited to 10*c .

30.    A Journal bearing 75mm long support a load of 7.5kN and the 50mm diameter. Journal running at 750rpm the diameter clearance is 0.0693mm. Determine the viscosity of oil if operating temp of bearing surface is limited to 77oC, Ambient temperature is 21oc heat dissipating co efficient is 210W /m^2/oc .

31.   In a journal bearing diameter of the shaft is 75 mm , L/D = 1 , Radial Clearance = 0.05 mm, Minimum film thickness = 0.002mm ,Speed of journal = 400 Rpm ,Radial Load = 3.5 KN , Specific gravity of oil =

0.9 , Specific heat of oil = 1.75 KJ/kgoC .Calculate the viscosity of suitable oil, Power lost in friction and resultant temperature rise.

UNIT-5

1.     Explain product development cycle.

2.    Explain the Shigley’s design process.

3.    Explain the Pahl and Beitz model.

4.    Explain the sequential engineering.

5.    Explain the concurrent engineering.

6.    Explain the 2D transformations with example.

7.    Explain the 3D transformations with example.

8.    Explain the w i r e f r a m e modeling.

9.    Explain the surface modeling techniques.

10.  Explain the solid modeling techniques.

11.  Compare wireframe model, surface model and solid model.

12.  Explain the basic steps of FEA.