GTU Paper Analysis (New Syllabus) Chapter 1 Design against ...€¦ · Chapter 2 –Design of Cotter & Knuckle joint. Sr. No. Questions Jun – 15 17 Jan –-16 Jun – 16 Nov –-16

GTU Paper Analysis (New Syllabus)

Machine Design & Industrial Drafting (2141907) Department of Mechanical Engineering Darshan Institute of Engineering & Technology

Chapter 1 –Design against static load

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1. Explain Mohr's circle diagram for principal stresses. 04 07 03

2. Differentiate between (with neat sketch): (1) crushing and compressive stresses (2) torsional and transverse shear stress.

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3. Name the different theories of failure of mechanical components made of ductile material. Explain the maximum shear stress theory giving conservative zone.

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4. Describe Hertz contact stress theory giving suitable example. 04

5. Explain maximum principal stress theory. 03

6. How will you select among different theories of failure? 03

7. What is impact load? 01

8. What is factor of safety? 01

9. What is Machine Design? Why the study of machine design is necessary? 01

10. Differentiate between crushing stress & bearing stress. 01

11. What are the reason for using factor of safety? Why its values are different for different applications?

03

12. What is stress concentration? Explain any two methods of reducing of it with neat sketches.

04

13. State the normal stress theory. 01

14. Explain maximum shear stress theory. 04

15. Name the different theories of failures of mechanical components made of ductile material. Explain the maximum shear stress theory giving conservative

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zone.

16. Explain selection and use of theories of failures. 03

17. Define factor of safety. List the factors affecting its value. 03 03

18. What is the difference between Drawing, Drafting and Design? 03

Examples

1.

Determine the principals stresses for 35mm rod diameter supported at end act

as cantilever beam which is subjected to an axial compressive load of 15KN &

twisting moment of 250 Nm.

04

2.

Calculate the diameter of a piston rod for a cylinder of 1.5 m diameter in which the greatest difference of steam pressure on two sides of piston may be assumed to be 0.2 N/mm2. The rod is made of mild steel and is secured to piston by a tapered rod and nut and to the crosshead by a cotter. Assume modulus of elasticity as 200 kN/mm2 and factor of safety as 8. The length of rod may be assumed as 3 m.

07

3.

The dimensions of an overhang crank are shown in Fig. The force P acting at crankpin is 1 kN. The crank is made of steel 30C8 with allowable shear stress 100 MPa. Using maximum shear stress theory of failure, determine the diameter at section XX.

04



4.

The load on a bolt consists of an axial pull of 10 KN together with a transverse shear force of 5 KN. Find the diameter of bolt required according to (i) maximum principal stress theory, (ii) maximum principal shear stress theory, (iii)maximum distortion energy theory. Take permissible tensile stress at elastic limit as 100 MPa and poison’s ratio as 0.3.

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5.

A cantilever beam of I-section supports an electric motor weighing 1000 N at a distance of 400 mm from the fixed end. If the allowable strength of the beam material is 100 N/mm2, determine the section of the beam. The proportions of I-section are B = 4t and H = 6t, where t is the thickness of the flange as well as that of the web.

04

6.

A bolt is subjected to a direct load of 25 kN and shear load of 15 kN. Considering (i) maximum normal stress (ii) maximum shear stress and (iii) von-Mises theories of failure, determine a suitable size of the bolt, if the material of the bolt is C15 having 200 N/mm2 yield strength. Take Factor of safety = 2.

07

7.

Determine the principal stresses for a 35mm diameter rod, supported at one end as a cantilever, subjected to an axial compressive load 15 KN and a twisting moment 250 N-m

04


Machine Design and Industrial Drafting (2141907) Department of Mechanical Engineering Darshan Institute of Engineering & Technology

Chapter 2 –Design of Cotter & Knuckle joint.

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1. Why taper is provided on cotter? What is its normal value? State its applications

03 01 03

2. Write any two applications of knuckle joint. 01

3. What is the function of cotter in cotter joint? Where it is used? 01 02

4. Explain with neat sketches failures in knuckle pin. 03

5. What are the possible failures of pin in knuckle joint? Explain with neat sketches.

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6. What is uniform strength concept used in the design of cotter joint? 04

Examples

1. Design a knuckle joint to transmit 75 kN. The design stresses may be taken as 75

MPa in tension, 60 MPa in shear and 150 MPa in compression. 07

07

2. Design and draw a neat sketch of spigot rod for the cotter joint using the following data. Axial load 30 KN, Tensile stress = 50 N/mm2, Crushing Stress = 90 N/mm2 And Shear Stress = 35 N/mm2

10

3. Design a knuckle joint to transmit 50 kN. The design stresses may be taken as 80 MPa in tension, 40 MPa in shear and 80 MPa in compression.

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4.

Calculate the dimensions of the socket end of a cotter joint used to connect two rods, made of plain carbon steel 40C8 having yield point strength 380 N/mm2. The diameter of each rod is 50 mm and the cotter is made from a steel plate of 15 mm thickness. Assume (i) the yield strength in compression is twice of the tensile yield strength, (ii) the yield strength in shear is 50 % of the tensile yield strength, (iii) the factor of safety is 6.

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5. Design a knuckle joint for a tie rod of a circular section to sustain a maximum pull of 70 KN. The ultimate strength of the material of the rod against tearing is

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420 MPa. The ultimate tensile and shearing strength of the pin material are 510 MPa and 396 MPa respectively. Determine the tie rod section and pin section. Take FOS=6.

6.

For a sleeve and cotter joint to resist a tensile load of 60 KN who’s all parts are made from same material with following allowable stresses. σt =60Mpa, τ = 70 MPa and σc =125 MPa. Find 1) Diameter of the rods, 2) Diameter of the enlarge end of the rod and thickness of cotter, 3) Outside diameter of sleeve.

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7. Design a cotter joint to connect two mild steel rods. The joint is subjected to a 20 kN tensile force. The allowable limits of tensile, shear and crushing strength are 60 N/mm2, 40 N/mm2 and 75 N/mm2.

07

8. Design a knuckle joint to connect two circular mild steel rods which are subjected to a tensile load of 63kN. The allowable stresses are: 80MPa in tension, 56 MPa in shear and 80MPa in crushing.

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Chapter 3 – Design of Lever.

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1. Explain with neat sketch three basic types of lever stating their practical

examples. 04

04

2. How is the leverage of compound lever calculated? 01 01

3. What is lever? Why they are usually made tapered? 04

4. What is the criterion of design of fulcrum pin in levers? 01

5. Define: Displacement Ratio 01

6. Why a boss is needed at a fulcrum of the lever? 01

7. What is lever? What are the different types of lever? 04

8. Briefly explain the general procedure for lever design. 07

Examples

1.

A bell crank lever is to be designed to raise a load of 6 KN at short arm end. The

arm lengths are 160 mm and 550 mm. The permissible stresses for lever and pin

materials in shear and tension are 60 MPa and 90 MPa respectively. The bearing

pressure on pin is to be limited to 13 MPa. Assume lever cross section as t×4t

and fulcrum pin length as 1.25 times pin diameter.

07

2.

Design a Bell crank lever having load arm 500mm and effort arm of 150mm respectively. The maximum load to be raise is 4500N. Use the following allowable stresses for the pin and lever material. Tensile Stress = 75 N/mm2,

Shear Stress= 60 N/mm2 & Bearing pressure = 10 N/mm2

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3. A lever loaded safety valve is 70 mm in diameter and is to be designed for a boiler to blow-off at pressure of 1 N/mm2 gauge. Design a suitable mild steel lever of rectangular cross-section. The permissible stresses are: Tensile stress

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= 70 MPa; Shear stress = 50 MPa; Bearing pressure intensity = 25 MPa. The pin is also made of mild steel. The distance from fulcrum to weight of lever is 880 mm and distance between fulcrum and pin connecting valve spindle links to lever is 80 mm.

4.

Design a right angled bell crank lever to raise a load of 6 kN at short arm. The lengths of short and long arms of a lever are 90 mm and 540 mm respectively. The lever and the pins are made of steel. The permissible stresses of steel are 80 N/mm2 in tension, 40 N/mm2 in shear and 10 N/mm2 in bearing. Assume the cross section of the lever as rectangular with depth as three times the thickness.

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5.

A bell crank lever is to be designed to raise a load of 15 KN at the short arm end. The arm lengths are 150 mm and 500 mm. The permissible stresses for lever and pin materials in shear and tension are 60 MPa and 90 MPa respectively. The bearing pressure on the pin is to be limited to 12 MPa. Assume the lever cross section as t x 4t and fulcrum pin length as 1.25 times pin diameter.

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Ch. 4 Design of Beams

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1. Differentiate between beam and column. Enlist different types of beams. 3 3

2. Distinguish between beams, columns and strut giving suitable examples. 7 3

3. State and explain the CASTIGLIANO’S theorem and determine the magnitude of strain energy stored for a cantilever beam subjected to torsional moment T having span length L and cross Sectional area A.

7 4

4. List out different types of supports. 1

5. Derive expressions for slope and deflection at the free end of a cantilever beam of length L carrying a couple moment M0 at its free end.

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6. Explain stress in beams. 3

Examples



Ch. 5 Design of Columns

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1. Explain Euler's formula along with its applicability and limitations. 3

2. What is slenderness ratio of column? How crippling stress is decided by using Euler’s equations? Give the validity of the equation.

7

3. What are the limitations of Euler’s equation how they are overcome? Explain the two empirical formulas with the name.

7

4. What is equivalent length of a column? 1

5. Define ‘slenderness ratio’. 1

6. Explain Rankine’s and Johnson’s formula for designing columns. 7

7. State the Rankine’s formula in the design of columns. 1

8. Differentiate between strut and column. 1

9. State the assumptions presume for the derivation of Euler’s formula. 3 1 4

10. Short note on Slenderness ratio. 4

11. Derive Rankine’s formula for buckling of column. 7

12. What do you mean by a column? What is the effect of end condition on the crippling load capacity of a column?

4

13. Define short columns, long columns and critical load of column. 3

Examples

1. A connecting rod of uniform rectangular cross-section having b/d ratio of 1.5

and length 100 mm is used for supporting an axial compressive load of 20 kN. It

is hinged at both ends and made of alloy steel with ultimate compressive

7

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strength of 700 MPa and modulus of elasticity of 210 GPa. Considering factor of

safety 4, determine cross-sectional dimensions using appropriate of Euler's and

Johnson's formulae.

2.

A 300 mm long alloy steel rod is used to support an axial compressive load of 65

kN. One end of rod is fixed and the other end is free to support load. Assuming

compressive yield strength 550 N/mm2 and modulus of elasticity 210 GPa,

determine diameter of rod by buckling consideration. Use Rankine's formula

with Rankine constant α = 1/7500. Take factor of safety 3.5.

7

3.

Calculate the diameter of a piston rod for a cylinder of 1.5 m diameter in which

the greatest difference of steam pressure on two sides of piston may be assumed

to be 0.2 N/mm2. The rod is made of mild steel and is secured to piston by a

tapered rod and nut and to the crosshead by a cotter. Assume modulus of

elasticity as 200 kN/mm2 and factor of safety as 8. The length of rod may be

assumed as 3 m.

7

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4. An I-section 400 mm x 200 mm x 10 mm and 3-meter-long is used as a strut with

both ends pinned. Find Euler’s crippling load. Assume Young’s modulus of

elasticity for the material of the section as 200 kN/mm2.

4

5.

Find the suitable size of 300 mm long push rod of a petrol engine carrying a

maximum load of 1400 N. It is hollow in section having the outer diameter 1.25

times the inner diameter. Spherical seated bearings are used for the push rod.

The modulus of elasticity for the material of the push rod is 210 kN / mm2.

Assume factor of safety of 2.5.

7

6.

A 25 X 50 mm bar of rectangular cross-section is made of plain carbon steel

40C8 (σyt = 380 N/mm2 and E = 207 000 N/mm2). The length of the bar is 500

mm. The two ends of the bar are hinged and the factor of safety is 2.5. The bar is

subjected to axial compressive force. (i) Determine the slenderness ratio; (ii)

Which of the two Equations-Euler’s or Johnson’s-will you apply to the bar? (iii)

What is the safe compressive force for the bar?

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Ch. 6 Design of Shaft, Keys and Couplings

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1. Explain Axle, Spindle, Counter shaft and line-shaft with their examples 4 1 3 4

2. What is ASME code for shaft design? 3 3 4

3. Derive strength equations of sunk key based on shear and compression failures. 4

4. Discuss factors to be considered while selecting type of key. 3

5. Compare the weight, strength and rigidity of a hollow shaft of same external diameter as that of solid shaft. Both the shafts are made of same material. Assume that the diameter ratio for the hollow shaft as 0.6.

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6. If the ratio of torque to bending moment on a shaft is 0.33, what would be the ratio of equivalent bending moment to equivalent torque?

1

7. Which stress is considered to design bolt in a flange coupling? 1

8. Deduce the design equation for shaft subjected to twisting moment only. 4

9. What is keyway? How is its effect considered in shaft design? 3

10. Explain different types of keys used in shaft coupling. 4 4 7 3

11. What is the difference between rigid coupling and flexible coupling? 1 3

12. Classify the couplings. 3 4

13. Compare the strength of square key and rectangular key, if the diameter of the shaft is 80 mm and length of key is 50 mm.

4

14. List out different types of keys. 1

15. Write down steps for design of shafts. 4

16. Compare hollow shaft and solid shaft. 3



17. Explain splines. 3

18. Give classification of shafts on basis of their industrial application. 3

19. Describe the muff coupling with neat sketch and indicate standard dimensions in it. Also write the design equation of muff coupling.

4

20. What are the requirements of good couplings? 4

21. Draw and design a bushed pin type flexible coupling. 7

22. How the hollow shafts are beneficial over the solid shaft? 3

Examples

1.

A hoisting drum 0.5 m in diameter is keyed to shaft which is supported in two bearings and driven through 12:1 reduction ratio by an electric motor. Determine power of driving motor, if maximum load of 8 kN is hoisted at speed of 50 m/min with 80% efficiency. Also determine torque on drum shaft and speed of motor in rpm. Determine also diameter of shaft for which working stresses are 115 MPa in tension and 50 MPa in shear. The drive gear whose diameter is 450 mm is mounted at end of shaft such that it overhangs nearest bearing by 150 mm. The combined shock and fatigue factors for bending and torsion may be taken as 2 and 1.5 respectively.

7

2.

A bushed pin type flexible coupling is used to transmit 10 kW power at 720 rpm. The design torque is 150% of rated torque. The keys have square cross-section. The permissible stresses are: For shaft and key material, τ = 66.67 N/mm2, σc = 200 N/mm2; For pin material, τ = 35 N/mm2, σt = 133 N/mm2; For flange material τ = 16.67 N/mm2. The permissible bearing pressure for rubber bushes is 1 N/mm2. The number of bushes is 4. Design the bushed pin flexible coupling.

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3.

Design a split muff coupling to transmit 30 KW power at 100 rpm, using the following data: Number of bolts = 4, allowable shear stress for shaft and key = 40 N/mm2, allowable tensile stress for the blots = 70 N/mm2. Take co-efficient of friction = 0.3.

7

4. Design a shaft to transmit power from an electric motor to a lathe head stock through a pulley by means of belt drive. The pulley weighs 200 N and is located

7



at 300 mm from centre of bearing. The diameter of pulley is 200 mm and maximum power transmitted is 1 kW at 120 rpm. The angle of lap of belt is 180° and coefficient of friction between belt and pulley is 0.3. The shock and fatigue factors for bending and twisting are 1.5 and 2.0 respectively. The allowable shear stress for shaft is 35 MPa.

5.

Design muff coupling to connect two steel shafts transmitting 40 kW at 350 rpm. The material for shafts and key is plain carbon steel for which allowable shear and crushing stresses are 40 MPa and 80 MPa respectively. The material for muff is cast iron for which allowable shear stress is 15 MPa.

7 7

6.

Design a shaft supported by two bearings placed 1 m apart. A 600 mm diameter pulley is mounted at a distance of 300 mm to the right of left hand bearing and this drives a pulley directly below it with the help of belt having maximum tension of 2.25 kN. Another pulley 400 mm diameter is placed 200 mm to the left of right hand bearing and is driven with the help of electric motor and belt, which is placed horizontally to the right. The angle of contact for both the pulleys is 180° and μ = 0.24. The allowing working stress of 63 MPa in tension and 42 MPa in shear for the material of shaft. Assume that the torque on one pulley is equal to that on the other pulley.

7

7.

Design a cast iron protective type flange coupling to transmit 15 kW at 900 r.p.m. from an electric motor to a compressor. The service factor may be assumed as 1.35. The shaft, bolt and key are made from steel having yield point stress and crushing stress of 160 N/mm2. The ultimate tensile strength of cast iron is 32 N/mm2. Assume the shear stress is half of the normal stress and factor of safety of 2.

7

8.

A 45 mm diameter shaft is made of steel with a yield strength of 450 MPa. A parallel key of size 14 mm wide and 9 mm thick made of steel with yield strength of 340 MPa is to be used. Find the required length of key, if the shaft is loaded to transmit the maximum permissible torque. Use maximum shear stress theory and assume a FOS=2.

7

9. Find the diameter of a solid shaft to transmit 30 kW at 230 rpm. The shear stress is 50 MPa. If a hollow shaft is to be used in place of solid shaft, find the inside and

7



outside diameters when the ratio of inside to outside diameter is 6:8.

10.

Design a cast iron split muff coupling to transmit a power of 10 kW at 250 rpm. Consider an overload of 25%. The allowable shear stress in the shaft and key is 36 MPa and for the muff 16 MPa. Take the co-efficient of friction 0.3 and the tensile strength of the high tensile bolts 150 MPa.

7

11.

It is required to design a square key for fixing a gear on the shaft which transmits 10 kW power at 720 rpm. The shaft and the key are both made of plain carbon steel C45 (σyt = 360 N/mm2) and the factor of safety is 3. Take allowable shear stress, τ = 0.577 σt.

7

12.

A flywheel is mounted on a horizontal shaft. The flywheel which also acts as pulley is of 1.5 m diameter and has belt tensions 5.4 kN and 1.8 kN on tight and slack side, respectively. The overhang of the flywheel is 250 mm. The weight of the flywheel is 15 kN. Determine the shaft diameter if the maximum allowable shear strength is 50 N/mm2. Design the shaft using ASME code. Consider shock and fatigue factors as 2 and 1.5 respectively.

7

13.

Design a cast iron protective type flange coupling to transmit 15 kW power at 900 r.p.m from an electric motor to a compressor. The service factor may be assumed as 1.7. The permissible stresses are as follows 1. Shear stress for shaft, bolt and key = 40 MPa 2. Crushing stress for bolt and key = 80 MPa 3. Shear stress for cast iron flange = 8 MPa Standard shaft diameters are: 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40. Take number of bolts as 3.

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14.

A 600 mm diameter pulley transmit 16kW power at a speed of 400 r.p.m. A pulley is mounted on a cantilever shaft at a distance of 200 mm from the nearest bearing. Two weight of pulley is 1500 N and is driven by a horizontal belt drive. If the co-efficient of friction between belt and pulley is 0.3 and the angle of lap is 180 , determine the shaft diameter.

7



Ch. 7 Design of Threaded joints

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1. Differentiate between power screw and threaded joint. 4

2. Define Pitch, Lead, Nominal diameter and Core diameter for power screw. 4

3. What do you mean by bolt of uniform strength? Explain with neat sketch. 3

4. Draw a neat sketch of turn buckle used for tie rods, giving design procedure. 7

5. What is self-locking screw? 1 1

6. Explain terminology of power screw with neat sketch. 3 4

7. Why nut is manufactured from phosphor bronze in case of power screws? 1

8. Define lead and state the relation between lead and pitch in case of threaded screws.

1

9. Explain different form of threads used in power screws. 3 3 3

10. Explain the phenomenon of self-locking and overhauling of power screws. 4 4

11. What are the advantages and disadvantages of threaded joints? 3 3

12. What is collar friction? 1

13. What is turn buckle? 1

14. Define power screw and state its applications. 4

15. Derive the expression for torque required to overcome collar friction. 7

16. Derive an equation for torque required to raise (lift) load by square threaded screw.

7



17. Derive the expression for torque and efficiency of a power screw. 7

18. Write application of screw threads. Also list most popular forms of threads. 3

19. Describe various locking systems for screw fastening to make it resistant to unscrewing under the effect of external force.

4

20. Draw the figure of different 1. Cap screws 2. Set screws. 4

Examples

1.

The nominal diameter of a triple threaded square screw is 50 mm, while pitch is 8 mm. It is used with a collar having outer diameter of 100 mm and inner diameter of 65 mm. The coefficient of friction at thread surface as well as at collar surface can be taken as 0.15. The screw is used to raise a load of 15 kN. Using uniform wear theory for collar friction, calculate: (i) Torque required to raise load, (ii) Torque required to lower load and (iii) Force required to raise load, if applied at a radius of 500 mm.

7

2.

A bracket is bolted to column by 6 bolts arrange in two columns. The distance between bolts along the row is 75mm and along the column 50mm. The joint is subjected to maximum eccentric force of 50KN acting at 150 mm away from the center of column. Taking allowable stress in the bolt as 150N/mm2, Determine the size of each bolt.

7

3.

A double threaded power screw with ISO metric trapezoidal threads with 15° semi-angle of thread is used to raise a load of 300 kN. The nominal diameter is 100 mm and pitch is 12 mm. the coefficient of friction at screw threads is 0.15. Neglecting collar friction, calculate; (i) torque required to raise the load, (ii) torque required to lower the load and (iii) efficiency of the screw.

7

4.

A power screw having double start square threads of 25 mm nominal diameter and 5 mm pitch is acted upon by an axial load of 10 kN. The outer and inner diameters of screw collar are 50 mm and 20 mm respectively. The coefficient of thread friction and collar friction may be assumed as 0.2 and 0.15 respectively. The screw rotates at 12 rpm. Assuming uniform wear condition at the collar and allowable thread bearing pressure of 5.8 N/mm2, find: (i) the torque required to rotate the screw; (ii) the stress in the screw; and (iii) the number of threads of nut in engagement with screw.

7



5.

A triple threaded power screw, used in a screw jack, has a nominal diameter of 50 mm and a pitch of 8 mm. The threads are square and the length of nut is 48 mm. The screw jack is used to lift a load of 7.5 KN. The coefficient of friction at the threads is 0.12 and collar friction is negligible. Calculate: (i) the principal shear stress in the screw body, (ii) the transverse shear stresses in the screw and the nut, (iii) the unit bearing pressure. State whether the screw is self-locking or not.

7

6.

A square threaded, triple start power screw, used in a screw-jack, has a nominal diameter of 50mm and a pitch of 8mm. the screw jack is used to lift a load of 7.5kN. The co-efficient of thread friction is 0.12 and collar friction is negligible. If the length of nut is 48mm, calculate 1. The principal shear stress in the body 2. The transverse shear stress in screw and nut and 3. The bearing pressure. State whether the screw is self-locking.

7



Chapter - 8 Design of Welded & Riveted joints

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1. Draw neat sketches of double V-Butt weld, single transverse fillet weld, single V-Butt weld and T-weld.

04

2. Draw neat sketch of Double riveted zig-zag butt joint with all terminology. 04 04

3. What do you mean by bolt of uniform strength? Explain with neat sketch. 03

4. What is circumferential riveted joint? 01

5. What would be the throat area of a fillet weld with equal legs of 6 mm and length of 1 cm?

01

6. What is caulking process as used in riveted joint? 01

7. Deduce the equation for strength of transverse fillet weld. 04

8. Draw neat sketch of Double riveted zigzag lap joint with all terminology 03

9. Deduce the design equation for circular fillet weld subjected to torsion. 04

10. List the types of riveted joints. 01

11. Draw welding symbol for 1)plug weld 2)spot weld 01

12. Draw rivet heads for 1)pan head 2)countersunk head 01

13. Classify and explain the types of welded joints with neat sketches and weld symbols.

07

14. Explain caulking & fullering in terms of riveted joint. 03

15. Define pitch, transverse pitch and diagonal pitch of riveted joints. 03

16. What do you mean by eccentric loaded welded joint? 03



17. Show, by neat sketches, the various ways in which a riveted joint may fail. 07

Examples

1.

Two steel plates, 120 mm wide and 12.5 mm thick, are joined together by means of double transverse fillet welds. The maximum tensile stress for plates and welding materials should not exceed 110 N/mm2. Find required length of weld, if strength of weld is equal to strength of plates.

03

2.

Find the value of P for joint shown in Figure 1, based on a working shear stress of 100 MPa for rivets. Each of four rivets is of 20 mm diameter.

3.

A bracket is bolted to column by 6 bolts arrange in two columns. The distance between bolts along the row is 75mm and along the column 50mm. The joint is subjected to maximum eccentric force of 50KN acting at 150mm away from the center of column. Taking allowable stress in the bolt as 150N/mm2, Determine the size of each bolt.

07

4.

A solid rectangular bar of 100mm width and 150mm depth is welded to vertical column by means of fillet weld all around. The joint is subjected to 25KN at distance of 500mm from the plane of weld. Determine throat thickness using allowable stress of weld is 75N/mm2

07

5. Design a double riveted zigzag lap joint for 13 mm thick plates. The allowable stresses are: σt = 80 MPa, τ = 60 MPa and σc = 120 MPa. State how the joint will fail and find efficiency of joint.

07

6. A steel plate 100 mm wide and 10 mm thick is welded to another steel plate by means of double parallel fillet welds as shown in figure given below. The plates

07



are subjected to a static tensile force of 50 KN. Determine the required length of the welds if the permissible shear stress in the weld is 94 N/mm2.

7.

A bracket is attached to a steel channel by means of nine identical rivets as shown in figure given below. Determine the diameter of rivets, if the permissible shear stress is 60 N/mm2

07

8.

A double riveted double cover butt joint in plates 30 mm thick is made with 35 mm diameter rivets at 100 mm pitch. The permissible stresses are σt =120MPa, τ = 100 MPa and σc =150 MPa. Find the efficiency of joint, taking the strength of the rivet in double shear as twice than that of single shear.

07

9.

A circular shaft, 75 mm in diameter, is welded to the support by means of a circumferential fillet weld. It is subjected to a torsional moment of 3000 N-m. Determine the size of weld, if the maximum shear stress in the weld is not to exceed 70 MPa.

07

10. Find the efficiency of the double riveted lap joints with zig-zag riveting is to 07



be designed for 13 mm thick plates. Assume 80 MPa, 60 MPa and 120 MPa in tension, Shear and crushing respectively. Also calculate pitch of rivets.

11.

A plate, 75 mm wide and 10 mm thick, is joined with another steel plate by means of single transverse and double parallel fillet welds, as shown in Fig. The joint is subjected to a maximum tensile force of 55 kN. The permissible tensile and shear stresses in the weld material are 70 N/mm2 and 50 N/mm2 respectively. Determine the required length of each parallel fillet weld.

07



12.

A bracket, attached to a vertical column by means of four identical rivets, is subjected to an eccentric force of 25 kN as shown in Fig. Determine the diameter of rivets, if the permissible shear stress is 60 N/mm2.

07



Ch. 9 Introduction of Limits, Fits and Tolerances

Sr.

No. Questions

Jun

e –

15

Jan

- 1

6

Jun

e -

16

No

v -

16

Jun

e -

17

No

v -

17

Ma

y -

18

De

c -1

8

1. Define Basic size, Tolerance and Deviation. 3 1 3 1 3

2. What are the parameters used for surface roughness measurement? Explain any

two. 4

3. What is magnitude of tolerance? Give the list of 6 manufacturing methods along

with the recommended tolerance grade. 7

4. Explain with the help of neat sketch the terminology used in relation with the

tolerances. 7

5. What is unilateral and bilateral tolerance? 1

6. What is deviation as used in fits? 1

7. How the surface finish is represented symbolically? 1

8. What is fit? Explain various types of fit with neat sketches. 3 4 4

9. “As the value of tolerances increases i.e. more precise tolerances, the cost of manufacturing the product is increases”, Justify the statement.

1

10. Draw the neat sketch of any two types of geometric tolerances and explain the meaning of each.

1

11. Give symbols for flatness, cylindricity, symmetry and straightness 3

12. Explain with neat sketches hole basis and shaft basis system of fits. 4



13. Draw standard symbol of surface roughness measurement. 3

14. Define basic size, actual size and limits 3

15. Define limits, fits and tolerance. 4

Examples

1.

In bush and pin assembly, pin of 30 mm diameter rotates in a bush. The

tolerance for pin is 0.025 mm while for bush is 0.04 mm. If allowance is 0.1 mm,

determine dimensions of pin and bush considering hole-basis system.

3

2.

A journal of nominal diameter 79 mm rotates in a bearing. The upper and lower

deviations in hole diameter are respectively +0.05 mm and 0.00 mm, while those

for shaft are respectively -0.03 mm and -0.07 mm. Calculate: (i) Extreme

diameters for hole and shaft, (ii) Tolerances for hole and shaft and (iii)

maximum and minimum clearance.

4

3. Find the tolerances, maximum interference and type of fit for the data as Hole ϕ50+0.25-0.10 and Shaft ϕ50+0.20-0.20.

4

4.

In a hub and pin assembly, the lower and upper limits on the inner diameter of the hub are 40.000mm and 40.021 mm respectively, while the lower and upper limits on the diameter of pin are 40.028 and 40.041mm respectively. Determine

(i) The tolerance on hub diameter; (ii) The tolerance on pin diameter; and (iii) The allowance. With the figure state the type of the fit of the assembly.

7

Documents

GTU Paper Analysis (New Syllabus) Chapter 1 Design against ...€¦ · Chapter 2 –Design of Cotter & Knuckle joint. Sr. No. Questions Jun – 15 17 Jan –-16 Jun – 16 Nov –-16