Showing posts with label ME6503. Show all posts
Showing posts with label ME6503. Show all posts

Monday, 23 November 2015

ME6503 Design of Machine Elements 2 marks

ANNA UNIVERSITY,CHENNAI
REGULATION 2013
DEPARTMENT OF MECHANICAL ENGINEERING

SUBJECT CODE:ME 6503

SUBJECT NAME:DESIGN OF MACHINE ELEMENTS

UNIT II SHAFTS AND COUPLINGS 

Design of solid and hollow shafts based on strength, rigidity and critical speed – Keys, key ways and splines - Rigid and flexible couplings.


PART-A ( Two Marks)

1.What is a shaft? List out the types of shafts.

A shaft is a rotating machine element,which transmits power from one point to another point.

Types of shafts:

i.Line shaft 
ii.Spindle 
iii. Stub shaft 
iv. Counter shaft

2.What is key?

Key is a device which is used for connecting tow machine parts for preventing relative motion of rotation with respect to each other.

Types of Keys:
 i. Saddle key 
ii.Tangent key 
iii.Sunk key 
iv.Round key and 
taper pins.

3.Define the term critical speed?

The speed at which the shaft runs so that the additional deflection of the shaft from the axis of rotation becomes infinite, is known as critical speed.

4.What are the types of Flexible coupling?

i.Universal coupling,
ii.Oldham’s coupling,
iii.Pushed pin type coupling.

5.What are the types of Rigid coupling?

i.Sleeve coupling, 
ii.Flange coupling, 
iii.Clamp coupling.

6.Under what circumstances flexible couplings are used?

They are used to join the abutting ends of shafts when they are not in exact alignment. They are used to permit an axial misalignment of the shafts without under absorption of the power, which the shafts are transmitting.  

7.How are sunk key designed?List the various failures occurred in sunk keys.

Sunk keys are designed to fit in a sunk key way. Whose bed is parallel to the axis of the shaft.

Various failures:
1.Shear failure 2.Crushing failure 

8.What is the function of a coupling between two shafts?

 Couplings are used to connect sections of long transmission shafts and to connect the shaft of a driving machine to the shaft of a driven machine.

9.What are the purposes in machinery for which couplings are used?

i.To provide the connection of shafts of units those are manufactured separately such as motor and generator and to provide for disconnection for repairs or alterations.
ii.To provide misalignment of the shafts or to introduce mechanical flexibility.
iii.To reduce the transmission of shock from one shaft to another. 
iv.To introduce protection against over load.

10.What are the different measures followed to control the lateral deflection?

i. Reducing the span length 
ii. Increasing the number of supports 
iii. Selecting the cross-section in which the area moment of inertia as in case of hollow shaft.


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Saturday, 14 November 2015

ME6503 DESIGN OF MACHINE ELEMENTS QUESTION BANK

ANNA UNIVERSITY CHENNAI
REGULATION 2013
ME6503-DESIGN OF MACHINE ELEMENTS
       UNIVERSITY QUESTIONS  

                                            UNIT-V
Click: DME previous 5 years Anna University Questions

1. List any two advantages of rolling contact bearings.

2. Define coefficient of steadiness.

3. What is meant by journal bearing?

4. Classify the types of bearings.

5. What is meant by life of anti-friction bearings?

6. What are the essential requirements in an end face seal?

7. State the merits of hydrostatic bearings.

8. Differentiate sliding contact and rolling contact bearings.

9. What is the illumination of McKee’s equation?

10. Distinguish between hydrostatic and hydrodynamic bearings.

11. Explain the term Dynamic load carrying capacities of rolling contact bearing.

Part - B

1. Design a journal bearing for a centrifugal pump with the following data: Diameter of the journal =150mm. Load on bearing=40KN, Speed of journal=900 rpm.

2. Select a bearing for a 40 mm diameter shaft rotates at 400 rpm. Due to bevel gear mounted on the shaft, the bearing will have to withstand a 5000N radial and a 3000N thrust load. The life of the bearing expected to be at least 1000 hrs.

3. A Single row deep groove ball bearing operating at 2000 rpm is acted by a 10 KN radial load and 8 KN thrust load. The bearing is subjected to a light shock load and the outer ring is rotating. Determine the rating life of the bearing.

4. Design a journal bearing for a centrifugal pump for the following data: Load on the journal =2000N; Speed of the journal=900 rpm; Type of oil is SAE 10, for which the absolute viscosity at C =0.17 N/m-s; Ambient temperature of oil=C, Maximum bearing pressure for the pump=1.5 N/.Calculate also mass of lubricating oil required for artificial cooling, if rise of temperature of oil be limited to C. Heat dissipation coefficient=1232W//oC.

5. A single row deep grove ball bearing is subjected to a radial force of 8 kN and a thrust force of 3kN. The shaft rotates at 1200 rpm. The expected life of the bearing of the shaft is 75mm. Select a suitable ball bearing for this application.

6. The radial reaction on a bearing is 8000N. It also carries a thrust of 5000N. The shaft diameter is 140mm and it rotates at 1700 rpm. Outer ring is stationery. Load is smooth, 8 hours/day for a life of 17000 hours. (a) Select a deep groove ball bearing. (b) What is the rated 90% life of the selected bearing? (c) For b= 1.34 compute the probability of the selected bearing surviving 17000 hours.

7. (a) Select a suitable deep groove ball bearing for supporting a radial load of 10 kN and an axial load of 3 kN for a life of 4000 hrs at 800 rpm. Select from series 63. Calculate the expected life of the selected bearing.

(b)  A journal bearing 150 mm diameter and 300 mm long carries a radial load of 9 kN at 1200 rpm. The diametral clearance is 0.075 mm. If 6 kW is being lost in friction, what is the viscosity of the oil used at given operating temperature?

 Click: DME previous 5 years Anna University Questions

For all units of design and machine elements and other mechanical engineering subjects study materials is uploaded see right side of the page you can download whatever materials you need to study or copy and paste the following link :annaunivstudymaterials.blogspot.com
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ME6503-DESIGN OF MACHINE ELEMENTS ANNA UNIVERSITY QUESTIONS

ANNA UNIVERSITY CHENNAI
REGULATION 2013
ME6503-DESIGN OF MACHINE ELEMENTS
       UNIVERSITY QUESTIONS  

                                            UNIT-III
Click: DME Unit 5 Question Bank

 PART-A

1. What are the different stresses setups in a bolt due to initial tightening?

2. Why reinforcement is normally required in welded joints?

3. How is a bolt designated?

4. Why are welded joints preferred over riveted joints?

5. Differentiate with a neat sketch the fillet welds subjected to parallel loading and

transverse loading?

6. What are different types of cotter joints?

7. State the two types of eccentric welded connections.

8. What is a gib? Why is it provided in a cotter joint?

PART-B

9. The cylinder head of a steam engine is subjected to a steam pressure of 0.7 N/mm². It is held in position by means of 12 bolts. A soft copper gasket is used to make the joint leak-proof. The effective diameter of cylinder is 300 mm. Find the size of the bolts so that the stress in the bolts is not exceed 100MPa.

10. A plate of 200mm width is welded to a vertical plate by fillet welding on three sides to form a cantilever with an overlap of 150mm and overhang of 400mm. A vertical downward load of 35kN is applied at free end for a weld stress of 75 N/mm². Determine the size of the weld.

11. A steam engine cylinder has an effective diameter of 350mm and the maximum steam pressure acting on the cylinder cover is 1.25 N/mm². Calculate the number and size of studs required to fix the cylinder cover. Assume the permissible stress in the studs to be 70 N/mm².

12. A bracket is welded to the vertical plate by mean of two fillet welds as shown in figure. Determine the size of the welds, if the permissible shear stress is limited to 70 N/mm².

13. A cast iron cylinder head is fastened to a cylinder of 500 mm bore with 8stud bolts. The maximum pressure inside the cylinder is 2MPa. The stiffness of part is thrice the stiffness of the bolt. What should be the initial tightening load so that the point is leak proof at maximum pressure? Also choose a suitable bolt for the above application.

14. (i) What is an eccentric loaded welded joint? Discuss the procedure for designing such a joint.

(ii) A 50mm diameter solid shaft is welded to a flat plate as shown in figure. If the size of the weld is 15mm, find the maximum normal and shear stress in the weld.

15. For supporting the traveling crane in a workshop the brackets are fixed on steel columns as shown in figure. The maximum load that comes on the bracket is 12 kN acting vertically at a distance of 400 mm from the face of the column. The vertical face of the bracket is secure dto a column by four bolts in two rows (two in each row) at a distance of 50 mm from the lower edge of the bracket. Determine the size of the bolt material is 84 Mpa. Also find the cross section of the arm of the bracket which is rectangular. 
16. Find the maximum shear stress induced in the weld of 6 mm size when a channel as shown in figure , is welded to a plate and loaded with 20 kN force at a distance of 200 mm.

For all units of DME and other mechanical engineering subjects study materials is uploaded see right side of the page you can download whatever materials you need to study or copy and paste the following link :annaunivstudymaterials.blogspot.com
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ME6503-DESIGN OF MACHINE ELEMENTS PREVIOUS QUESTIONS

ANNA UNIVERSITY CHENNAI
REGULATION 2013
ME6503-DESIGN OF MACHINE ELEMENTS
                                 UNIVERSITY QUESTIONS 
                                                                                                                                                                                                                                    Click: DME Unit 1 Question Bank
Click: DME Unit 5 Question Bank

 UNIT-2                                                                                                                                                       TWO MARKS
1. On what basis are shafts designed?

2. What are the effects of introducing keyways in shafts?

3. What is the use of register in a flange coupling?

4. How is the strength of a shaft affected by the Keyway?

5. What are the various stresses induced in the shafts?

6. Name any two of the rigid coupling.

7. A shaft of 70mm long is subjected to shear of 40 MPa and has an angle of twist equal to 0.017 radian.Determine the diameter of the shaft. Take G = 80 GPa.

8. What is the main use of woodruff keys?

9. Why a hollow shaft has greater strength and stiffness than solid shaft of equal weight?

10. Under what circumstances flexible couplings are used?

11. What are the various stresses induced in the shafts?

12. Name the two of the rigid coupling.

13. What is the difference between rigid and flexible coupling?

14. Classify keys with its applications.

15. Write the advantages of the knuckle joints.

16. State Castiglione's theorem.

Click: DME Unit 5 Question Bank

 16 MARKS

1. A hollow transmission shaft having inside diameter 0.6times the outside diameter is made of plain carbon steel 40C8 and the factor of safety is 3. A belt pulley, 1000mm in diameter, is mounted on the shaft which overhangs the left hand bearing by 250mm.The belts are vertical and transmit power to the machine shaft below is 3kN and 1 kN respectively, while the weight of the pulley is 500N. The angle of wrap of the belt on the pulley is 180o. Calculate the outside and inside diameter of the shaft.

2. The layout of a shaft carrying two pulleys 1 and 2, and supported on two bearings A and B is shown in figure. The shaft transmits 7.5 k W power at 360 rpm from pulley 1 to pulley 2. The diameters of pulley 1 and 2 are 250 mm and 500 mm respectively. The masses of pulley 1 and 2 are 10 and 30 kg respectively. The belt tensions act vertically downward and ratio of belt tensions on the tight side to slack side for each pulley are 2.5:1. The shaft is made of plain carbon steel 40 C8 (Syt) = 380 N / mm2) and the factor of safety is 3. Estimate suitable diameter of shaft. If the permissible angel of twist is 0.5° per meter length, calculate the shaft diameter on the basis of tensional rigidity. Assume G = 79300 N / mm2

3. A steel solid shaft transmitting 15 kW at 200 rpm is supported on two bearings 750 mm apart and has two gears keyed to it. The pinion having 30 teethes of 5mm module is located 100mm to the left of the right hand bearings and delivers power horizontally to the right. The gear having 100 teeths of 5 mm module is located 150 mm to the right of the left hand bearing and receives power in a vertical direction from below. Using an allowable stress of 54 MPa in shear. Determine the diameter of the shaft.

4. A steel solid shaft transmitting 15 kW at 200 rpm is supported on two bearings 750 mm apart and has two gears keyed to it. The pinion having 30 teeths of 5mm module is located 100mm to the left of the right hand bearings and delivers power horizontally to the right. The gear having 100 teeths of 5 mm module is located 150 mm to the right of the left hand bearing and receives power in a vertical direction from below. Using an allowable stress of 54 MPa in shear. Determine the diameter of the shaft.

5. A horizontal nickel steel shaft rests on two bearings, A at the left and B at the right end and carrier two gears C and D located at distance of 250 mm and 400 mm respectively from the centre line of the left and right bearings. The pitch diameter of the gear C is 600 mm and that of gear D is 200 mm. The distance between the centre line of the bearing is 2400 mm. The shaft transmits 20kW at 120 rpm. The power is delivered to the shaft at  gear C and is taken out at gear D in such a manner that the tooth pressure Ftc of the gear C and Ftd of the gear D act vertically downwards.
6. Find the diameter of the shaft, if the working stress is 100MPa in tension and 56 MPa in shear. The gear C and D weights 950 N and 350 N respectively. The combined shock and fatigue factors for bending and torsion maybe taken as 1.5 and 1.2 respectively.

7. A hollow shaft for a rotary compressor is to be designed to transmit a maximum torque of 3500 N-m. The shear stress in the shaft is limited to 50Mpa.Determine inside and outside diameter of the shaft, if the ratio of inside and outside diameter is 0.4.

8. A hoisting drum 0.5 m in diameter is keyed to a shaft which is supported in two bearings and driven through a 12:1 reduction ratio by an electric motor. Determine the power of the driving motor, if the maximum load of 8 kN is hoisted at a speed of 50 m/min and the efficiency of the drive is 80%. Also determine the torque on the drum shaft and the speed of the motor in rpm. Determine also the diameter of the shaft made of machinery steel, the working stresses of which are 155 MPa in tension and 50 MPa in shear. The drive gear whose diameter is 450 mm is mounted at the end of the shaft such that it overhangs the nearest bearing by 150 mm . The combined shock and fatigue for bending and torsion may be taken as 2 and 1.5 respectively

9. A rigid type of coupling is used to connect two shafts transmitting 15kW at 200 rpm. The shaft keys and bolts are made of C45 steel and the coupling is cast iron. Design the coupling.

10. A turbine shaft transmits 500kw at 900 rpm. The permissible shear stress is 80 N/mm^2 while twist is limited to 0.5 degree in a length of 2.5 m. calculate the diameter of the shaft. take G=0.8 *105 N/mm2. if the shaft chosen as hollow with d3/d03 = 0.6. Calculate the percentage of saving in material.

11. Determine the dimension of flange coupling that connects a motor and a pump shaft. The power to be transmitted a 2 kW at a shaft speed of 960 rpm. Select suitable materials for the parts of the coupling and list the dimensions.

12. Design a muff coupling to connect two steel shafts transmitting 25 kW power at 360 rpm. The shafts and key are made of plain carbon steel 30C8.The sleeve is made of grey cast iron FG 200.The factor of safety is the shaft and key is 4.Foe example the sleeve ,the factor of safety is 6 based ultimate strength.

13. Determine the dimension of flange coupling that connects a motor and the pump shaft. The power to be transmitted a 2kW at a shaft speed 960 rpm. Select suitable materials for the parts of the coupling and the dimensions.

14. A hoisting drum 0.5 m in diameter is keyed to a shaft which is supported in two bearings and driven through a 12:1 reduction ratio by an electric motor. Determine the power of the driving motor, if the maximum load of 8 kN is hoisted at a speed of 50 m/min and the efficiency of the drive is 80%. Also determine the torque on the drum shaft and the speed of the motor in rpm. Determine also the diameter of the shaft made of machinery steel, the working stresses of which are 155 MPa in tension and 50 MPa in shear. The drive gear whose diameter is 450 mm is mounted at the end of the shaft such that it overhangs the nearest bearing by 150 mm. The combined shock and fatigue for bending and torsion may be taken as 2 and 1.5 respectively

15. Design a bushed-pin type of flexible coupling to connect a pump shaft to a motor shaft transmitting 32kW at 960 rpm. The overall torque is 20% more than mean torque. The material properties are as follows:
(i) The allowable shear and crushing stress for shaft and key material is 40 MPa and 8-MPa respectively.(ii) The allowable shear stress for cast iron is 15 MPa(iii) The allowable bearing pressure for rubber is 0.8 N/mm2(iv) The material of the pin is same as that of shafts and key.Draw neat sketch of the coupling.

16. Design a protective type flange coupling to connect two shafts to transmit 15kW at 600 rpm.
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ME6503 Design of Machine Elements University Questions

ME6503-Design of Machine Elements
Regulation 2013

Important 2 marks and 16 marks questions
Unit-1
                                             2 MARKS

Click: DME previous 5 years Anna University Questions

1. How do you classify materials for engineering use?

2. How is the working stress calculated from the yield stress of a material?

3. List the various steps involved in the design of a machine element?

4. Compare the characteristics of Gerber curve Soderberg and Goodman lines?

5. List any two factors that influence magnitude of factor of safety?

6. State maximum shear stress theory of failure?

7. Differentiate between hardness and toughness of materials?

8. Define stress concentration and stress concentration factor?

9. Describe the material properties of hardness, stiffness and resilience?

10. What are the methods used to improve fatigue strength?

11. What are the factors to be considered for deciding the magnitude of factor of safety?

12. List out methods of reducing stress concentration factor?

13. What is ‘Adaptive design’? Where is it used? Give examples

14. State difference between straight beams and curved beams?

16 MARKS

1. A hot rolled steel shaft is subjected to a torsional moment that varies from 330Nm clockwise to110Nm counter clockwise and an applied bending moment at a vertical section and no keyway is present at the critical section. Determine the required shaft diameter .the material has an ultimate strength of 550Mpa and yield strength of 410Mpa.take the endurance limit as half the ultimate strength, factor of safety of 2, size factor of 0.85 and a surface finish factor of 0.62

2. A bar of circular cross-section is subjected to alternating tensile forces varying from a  drawn diameter of the bar using safety factors of 3.5 related to ultimate tensile strength and 4 related to an durance limit and a stress concentration factor of 1.65 for fatigue load. Use Goodman straight line as basis for design.

3. A hollow shaft of 40mm outer diameter and 25mm inner diameter is subjected to a twisting moment of 120 N-m, simultaneously; it is subjected to an axial thrust of 10Kn and a bending moment of 80N-m.calculate the maximum compressive and shear stresses.

4. A pulley is keyed to a shaft midway between two bearings. The shaft is made of cold drawn steel for which the ultimate strength is 550MPa and the yield strength is 400Mpa. The bending moment at the pulley varies from -150N-m to +400Mpa.as the torque on the shaft varies from -50Nm to +150Nm. obtain the diameter of the shaft for an indefinite life. The stress concentration factors for the keyway at the pulley in bending and in torsion are 1.6 and 1.3 respectively. Take the following values: factor of safety =1.5; load correction factors=1.0 in bending, and 0.6 in torsion; size effect factor=0.85; surface effect factor=0.88.

5. A hollow shaft is required to transmit 600kW at 110 r.p.m., the maximum torque being 20% greater than  the mean. The shear stress is not to exceed 63MPa and twist in a length of 3 meters not to exceed 1.4 degrees .find the external diameter of the shaft, if the internal diameter to the external diameter is 3/8. Take modulus of rigidity as 84GPa.

6. A Machine component is subjected to fluctuating stress that varies from 40 to 100N/mm2. The corrected endurance limit stress for the machine component is 70N/mm2. The ultimate tensile strength and yield strength of material are 600 and 450N/m2 respectively .find the factor of safety using: (a).Gerber theory; (b) Soderberg line; (c). Goodman line; and (d). Also, find factor of safety against static failure.

7.A Pulley is keyed to a shaft midway between two anti-friction bearings. The bending moment at the pulley varies from -170Nm to 510Nm as the torsional moment in the shaft varies from 55N m to 165Nm.The frequency of variation of the loads is the same as the shaft speed. The shaft is made of cold drawn steel having an ultimate strength of 538Mpa and yield strength of 400Mpa. Determine the required diameter for an infinite life. The stress concentration factor for the keyway in bending and torsion may be taken as 1.6 and 1.3 respectively. Use design factor 
N=1.5

8. A bolt is subjected to a tensile load of 25 KN and to a shear load of 10KN.suggest a suitable size of a bolt according to various theories of failure. Take allowable yield stress is 300N/mm2,poisson’s ratio is 0.25

9. A 50 mm diameter shaft is made from carbon steel having ultimate tensile strength of 600Mpa. It is subjected to a torque which fluctuates between2000 N-m to -900N-m. Using soderberg method calculates the factor of safety.

10. (i) What are the factors influencing machine design? Explain it.

(ii) Write short notes on the following:

a. interchangeability

b. tolerance

c. allowance

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annaunivstudymaterials.blogspot.com
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