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Sunder deep Engg. College, GhaziabadB.Tech(ME), (Sem-V),2012

Question BankMachine Design-I (EME-501)

UNIT-I Qus.1 Discuss need based analysis.

Qus.2 Discuss design by evolution.

Qus.3 What do you mean by evolution.

Qus.4 What do you mean by technology based developments?

Qus.5 Differentiate between old and new design approaches.

Qus.6 Discuss various stages in morphology of design.

Qus.7 Discuss standardization and interchangeability.

Qus.8 Define creativity? Explain difference between creativity thinking and analytical thinking.

Qus.9 What are the barriers to creativity or mental blocks.

Qus.10 Explain Design methods: i) Black box. ii) Glass box.

Qus.11 What is machine design?

Qus.12 Explain the various considerations influencing the machine component design.

Qus.13 what is standardization? Explain its significance.

Qus.14 What are preferred number series? State their advantages and applications.

Qus.15 Explain what do you understand by “Mechanical Engineering Design”? Define standardization. Explain various stander used in machine design.

Prepared by: Bhanu P. Srivastava Assitanat Professor

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Qus.16 A manufacturer is interested to start the business with six different model of machine ranging from 7.5KW to 75KW. Specify the power capacities of the models.

Qus.17 What is Mechanical Engineering design?

Qus.18 Explain the various phase involved in the process of Machine design.

Qus.19 What is the necessity of having more than one theory of failure? State max. shear stress theory and show that it is more suitable for ductile material in comparison to max. principle stress theory.

Qus.20 What do you understand by ‘hot working’ and ‘cold working’ processes? Explain with examples.

Qus.21What do you understand by ‘design by evolution’? State its limitation.

Qus.22 What do you understand by ‘design by innovation (technology based development)’?

Qus.23 What is ergonomics? Discuss its scope in machine design.

Qus.24 Designate the following materials(a) Grey cast iron with ultimate tensile strength of 350 MPa (b) Plain carbon steel with a minimum tensile strength of 340 MPa(c) Plain carbon steel with a minimum yield strength of 240 MPa(d) Plain carbon steel with a 0.45% carbon and 0.8%Mn.(e) Alloy steel with carbon = 0.4-0.50% and chromium = 0.90-1.2 %. .

Qus.25 (i) What is the criterion of failure for ductile material subjected to static load ? (ii) Write about the various theory of failure.

Qus.26 A mild steel shaft of 4cm diameter is subjected to bending moment of 15KNcm and torque T. without causing yielding of the shaft according to (i) Maximum principal stress theory (ii) The max. shear stress theory.

Qus.27 (a) Define Hooks law and what is strain and stress?


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(b) What is resilience? (c) What is Ductility and brittleness? (d) Define young’s modules of elasticity (e) Define toughness and hardness. (f) What is the type of strength? Qus.28 what are stiffness and creep.

Qus.29 what are the endurance limit.

UNIT-II

Qus.1 A rectangular plate 50 mm x 10 mm with a hole 10 mm diameter is subjected to an axial load of 10 kN. Taking stress concentration into account, find the maximum stress induced.

Qus.2 A leaf spring in an automobile is subjected to cyclic stresses. The average stress = 150 MPa; variable stress = 500 MPa; ultimate stress = 630 MPa; yield point stress = 350 MPa; and endurance limit = 150 MPa. Estimate, under what factor of safety the spring is working, by Goodman and Soderberg formula.

Qus.3 What is material used for rivets?

Qus.4 What do you understand by the term riveted joint? Explain the necessity of such a joint.

Qus.5 Classify the rivet heads according to Indian standard specifications.

Qus.6 Explain the procedure the for designing a longitudinal and circumferential joint for a boiler.

Qus.7 Describe the procedure for designing a lozenge joint.

Qus.8 What is an eccentric riveted joint? Explain the method adopted for designing such a joint?

Qus.9 What is difference between caulking and fullering? Explain the help of neat sketches.

Que.10 Show by neat sketches the various ways in which a riveted joint may fail.


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Qus.11 What do you understand by term ‘efficiency of riveted joint’?

Qus.12 A single riveted lap joint is made in 15 mm thick plates with 20 mm diameter in rivets. Determine the strength of the joint, if the pitch of rivet is 60 mm. Take σ t = 120MPa; τ = 90MPa; and σ c = 160MPa.

Qus.13 Two plates 16 mm thick are joined by a double riveted lap joint. The pitch of each row of rivets is 90 mm. the rivets are 25 mm in diameter. The permissible stresses are as follows: σ t = 140MPa; τ = 110MPa; and σ c = 240MPa. Qus.14 Design a triple riveted double straps butt joint with chain riveting for a boiler of 1.5 mm diameter and carrying a pressure of 1.2 N/mm2. The allowable stresses are: σ t = 105MPa; τ = 77MPa; and σ c = 162.5MPa

Qus.15 Enumerate the different types of riveted joints and rivets.

Qus.16 A bracket is supported by means of 4 rivets of size, as shown by fig. determine the diameter of the rivet if the maximum shear stress is 140MPa.

K = (4c - 1) / (4c – 4) + (0.615) / c

Qus.17 Explain the following terms in connection with design of machine members subjected to variable loads:(a) Endurance limit, (b) Size factor, (c) Surface finish factor, and (d) Notch sensitivity

Qus.18 What is meant by ‘stress concentration’? How do you take it into consideration in case of a component subjected to dynamic loading? Qus.19 Write soderberg’s equation and state its application to different type of loadings.

Qus.20 What information do you obtain from soderberg diagram?

Qus.21 Write down the expression for strength of parallel fillet weld in terms ofpermissible shear stress, leg of weld and length of welded joint.


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Qus.22 Two rods, made of plain carbon steel 40C8(Syt= 380N/mm2) are connected by means of a cotter joint. The diameter of each rod is 50 mm and the cotter is made from a steel plate of 15 mm thickness. Calculate the dimensions of the socket end making thefollowing assumptions:

The yield strength in compression is twice of the tensile yield strength; and The yield strength in shear is 50% of the tensile yield strength. The factor of safety is 6.

Qus.23 Explain in detail the maximum shear stress theory.

Qus.24 A rod of a linkage mechanism made of steel40Crl (Sut = 550N/mm2 ) is subjected to a completely reversed axial load of 100 kN. The rodis machined on lathe and the expected reliability is 95%.There is nostress concentration. Determine the diameter of the rodusing a factor of safety of 2 for an infinite life condition.

Qus.25 Explain Soderberg and Goodman lines in detail.

Qus.26 Two length of mild steel tie rod having with 200mm and thickness 12.5mmare to be connected by means of a butt joint with double cover plates.Design the joint if the permissible stresses are 80 N/mm2 in tension, 65 N/mm2 in shear and 160 N/mm2 in crushing.

Qus.27 An eccentrically loaded lap joint is to be designed for bracket. The bracketplate thickness is 25mm. All rivets are to be of the same diameter. Loadon bracket is 50KN. Rivet spacing C = 100mm, eccentrically e = 400mm. Permissible stress is 120MPa. Compute the size of the rivets to be used for the joint.

Qus.28 Design double riveted butt joint with two cover plates for the longitudinal seam of a boiler shell 1.5m in diameter subjected to a steam pressure of 0.95KN/m2. Assume joint efficiency as 75% allowable tensile stress in the plate 90 N/mm2, compressive stress 140 N/mm2 and shear stress in the rivet 56 N/mm2.


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UNIT-III

Qus.1 A 1m length of commercial steel shafting is to transmit 65kW at 3600rev/min through flexible coupling from an AC motor to a D.C generator. Determine the required shaft size.

Qus.2 A section of commercial shafting 2m long between bearing carries a 1000N pulley at its midpoint, as shown fig. given below. The pulley is keyed to the shaft and receives 30 kW at 150 rev/min which is transmit to flexible coupling just outside the right bearing.The belt drive is horizontal and the sum of the belt tension is 8000N. Assume Kt= Kb = 1.5. Calculate the necessary shaft diameter and determine the angle of twist between bearing. G = 80GN/m2.

Qus.3 A line shaft rotating at 200 rpm is to transmit 200 KW. The allowable shear stress for material of the shaft is 42 MPa. If the shaft carries a central load of 900 N and is SSB bearing 3 m apart, determine the diameter of the shaft. The maximum tensile strength or compressive stress is not exceed 56 MPa.

Qus.4 A cylindrical shaft, made of steel of yield strength 760 MPa, is subjected to a static load of consisting of bending moment of 15KNm and a torsional moment of 25 KNm . Determine suitable diameter of shaft using maximum shear stress theory and maximum srain energy theory, assuming a factor of safety 2.5. (Take E= 200Gpa and poisson’s ratio = 0.25).

Qus.5 A shaft is subjected to a bending moment of 15 Nm and transmits 5KW at 500 rpm. The permissible shear stress for shaft material is 40 N/mm2., and tensile stress (permissible) is 58 N/mm2. Find the suitable diameter of shaft so that max. shear stress and max. tensile stress induced in the shaft is within permissible limit.

Qus.6 What is key ? State its function.

Qus.7 What is the effect of keyway cut into the shaft?

Qus.8 In what situation is flexible coupling used?

Qus.9 What is a stud?


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Qus.10 A solid shaft of diameter 'd' is used in power transmission. Due to modification of existing transmission system, it is required to replace the solid shaft by a hollow shaft of the same material and equally strong in torsion. Further, the weight of hollow shaft per meter length should be half of the solid shaft. Determine the outer diameter of hollow shaft in sterms of d.

Qus.11 It is required to design a rigid type of flange coupling to connect twoshafts ..The input shaft transmits 37.5 kW power at 180 rpm to theoutput shaft through the coupling. The service factor for the applicationis 1.5, i.e. the design torque is 1.5 times of rated torque. Select suitablematerials for various parts of the coupling, design the coupling andspecify the dimensions of its components.

Qus.12 Design a rigid muff coupling and sketch it. A muff made of cast iron is used to connect two steel shafts transmitting 25KW at 300rpm. The material for the shaft and key is plain carbon steel for which allowable shear and crushing stresses are 42 N/mm2 and 100 N/mm2 respectively. The allowable shear stress for C.I is 16N/mm2 .

Qus.13 A mild steel shaft transmits 20 KW at 200rpm. It carries a central load of 900N and is simply supported between the bearings of 2.4 meters apart. Determine the size of the shaft, if the allowable shear stress is 42MPa & the maximum tensile or compressive stress is not to exceed 56MPa. What size of the shaft will be required, if it is subjected to gradually applied loads.

Qus.14 A hollow shaft of 0.5m outside diameter and 0.3m inside diameter is used to drive a propeller of a marine vessel. The shaft is mounted on bearings 6m apart and it transmits 5600KW at 150rpm. The maximum axial propeller thrust is 500 KN and the shaft weighs 70KN. Determine the maximum shear stress developed in the shaft and the angular twist between the bearings.

Qus.15 A shaft transmits power 2 KW at 150 rpm from the electric motor head stock of lathe by means of a vertical belt drive. The co-efficient of friction for the belt for the belt is 0.3 and the angle of wrap is 1800. The weight of the pulley is 150N. the shaft material has ultimate stress is 770 N/mm2 ,yield stress is 560 N/mm2. Kb = Kt = 1.5. Determine the shaft diameter.

Qus.16 Design a bushed – pin flexible coupling for the following data, P = 20KW at 769 rpm. Allowable stresses are as follows in tension 60 N/mm2, in shear 59 N/mm2, in crushing 120 N/mm2 . design torque is 1.5 times of mean torque.


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Qus.17 Design and draw a cast iron protective type flange coupling to transmit 15KW at 900 rpm from an electric motor to a compressor. The service factor may be assumed as 1.35. the following permissible stresses may beused. Permissible shear stress for shaft, bolt and key material is 40 MPa. Permissible crushing stress for bolt and key material is 80 MPa, permissible shear stress for cast iron material is 8 MPa.

Qus.18 Specify the types of shafts.

Qus.19 What is the significance of slenderness ratio in shaft design?

Qus.20 Define critical speed of shaft.

Qus.21 Explain torsional stiffness of the shaft.

Qus.22 What is key? Describe the types of keys.

Qus.23 What is coupling? Describe the types of couplings.

Qus.24 What are the stresses induced in shaft?

Qus.25 What is the effect of keyway cut into the shaft?

Qus.26 Differentiate joint and coupling.

Qus.27 What is the difference between axle and spindle?


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UNIT-IV

Qus.1 Determine the required number of coil and permissible deflection in a helical spring made of 1.6mm diameter steel wire, assuming spring index of 6 and an allowable stress of 345 MN/m2 in shear. The spring rate should be 1800 N/m.

Qus.2 Derive the stress, force, and deflection relationships for multi-leaf springs.

Qus.3 Derive the stress, force, and defection relationship for helical coil spring for concentric axial load.

Qus.4 A 1m long cantilever spring is composed of 8 graduated leaves and extra full length leaf. The leaf is 45mm wide. A load of 2000N at the end of the spring causes a deflection of 75mm. Determine the thickness of the leaves and maximum bending moment in the full length leaf assuming first that the extra full length leaf has been pre-stressed to give the same stress in all the leaves, and then determine the stress in the full length leaf assuming no pre-stress.

Qus.5 Determine the required number of coil and permissible deflection in a helical spring made of 1.6mm diameter steel wire, assuming spring index of 6 and an allowable stress of 345 MN/m2 in shear. The spring rate should be 1800 N/m.

Qus.6 Design a coil spring have mean diameter of 125mm and spring rate of 72KN/m. The total axial load is 8000N and the allowable shear stress is 275 MN/m2.

Qus.7 Write down a design procedure of screw jack.

Qus.8 A double – threaded power screw, with metric trapezoidal thread, is used to raise load of 400kN. The nominal diameter is 100mm and the pitch is 12mm. The coefficient of friction at screw thread is 0.15. Neglecting collar friction, design the power screw and calculate the torque required to raise and to lower the load and also find out efficiency of the screw.

Qus.9 A helical compression spring is used to absorb the shock. The initialcompression of the spring is 30 mm and it is further compressed by50 mm while absorbing the shock. The spring is to absorb 250 J of energyduring the process. The spring index can be taken as 6. The"spring ismade of patented and cold drawn steel wire with ultimate strength of1500 Nzmm'' and modulus of rigidity of 81370 Nzmm-, The permissible shear stress for the spring wire should be taken as 30% of the ultimatetensile strength. Design the spring and calculate:(i) Wire diameter


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(ii) Mean coil diameter(iii) Number of active turns(iv) Free length; and(v) Pitch of the turns.

Qus.10 Design a helical spring for a spring-loaded safety valve for the followingconditions:Operating pressure = 1N/mm2Maximum pressure when the valve blows off freely = 1.075N/mm2Maximum lift of the valve when the pressure is 1.075N/mm2 is 6mm.Diameter of valve seat = 100mmMaximum shear stress = 400Mpa.Modulus of rigidity = 86kN/mm2Spring index = 5.5

Qus.11Design a helical spring for an engine valve length of the spring when the valvein open in 45mm. and the length when closed in 55mm. spring load on the valve when open is 450N and when closed in 300N. Minimum internal diameter of the spring is 30mm. Take permissible shear stress = 400 N/mm2, and G = 0.8 x 105 N/mm2.

Qus.12 Design a helical compression spring for a maximum load of 1000N for adeflection of 2.5 mm using the valve of springs index as 5. The maximum permissible shear stress for spring wire is 420N/mm2 and modulus of rigidity is 84kN/mm2 Take wahls factor

where c is spring index.

Qus.13 A helical valve spring is to be designed for an operating load range of 90N to135N. The deflection of the spring for this load range is 7.5 mm. Assuming a spring index of 10, a permissible shear stress of 80 n/mm2 for the material and modulus of rigidity of 0.8 X 105 N/mm2. Determine the dimensions of the spring. Sketch the spring with dimensions indicated.

Qus.14. A helical spring whose mean diameter of coil is 8 times that of wire is toabsorb 400 N-m of energy. The initial compression of the spring is 50 mm andcompresses by additional 70 mm while absorbing the shock. The maximum allowable stress is 400 MPa and G = 84 x 103 MPa. Determine the diameter of the wire and thenumber of active turns. Neglect the effect of stress concentration.


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Qus.15 A carriage spring 800mm long is required to carry a proof load of 5000N at thecentre. The spring is made of plates 80mm wide and 7.5mm thick. If the maximum permissible stress for the material of the plates is not to exceed 190Mpa, determine: number of plates required, deflection of spring, and the radius to which the plates must be initially bent. The modulus of elasticity may be taken as 205kN/mm2.

Qus.16 A semi elliptical laminated spring 900mm long and 55mm wide is head together at the centre by a band 50mm wide. If the thickness of each leaf is 5mm. Find the number of leaves required to carry a load of 4500N. Assume a maximum working stress of 490 N/mm2. If the two of those leaves extend the full length of the spring find the deflection of spring. The young’s modulus for the spring materials may be taken as 210 kN/mm2.

Qus.17 A locomotive spring has an overall length of 1.1m and sustained a load of 75kN at its centre. The spring has 3 full length leaves and 15 graduated leaves with a central band of 100mm wide. All leaves are to be stresses to be approximately 2. Take E=2.1 x 105 N/mm2(a) Determine the width and thickness of the leaves.(b) Determine the initial space that should be provided between the full length and graduated leaves before the band load is applied.(c) What load is exerted on the band after the spring is assembled?

Qus.18 A helical spring is made from a wire of 6 mm diameter and has outside diameter of 75 mm. If the permissible shear stress is 350 MPa and modulus of rigidity 84 KN/mm2. Find the axial load which the spring can carry and the deflection per active turn.

Qus.19 Design a helical compression spring for a maximum load of 1000 N for adeflection of 25 mm using the value of spring index as 5. The maximum permissible shear stress for spring wire is 420 MPa and modulus of rigidity is 84 KN/mm2.

Qus.20 Design a close-coiled helical compression spring for a service load ranging from 2250 N to 2750 N. The axial deflection of the spring for the load range is 6 mm. Assume a spring index of 5. The permissible shear stress intensity is 420 Mpa and modulus of rigidity 84 KN/mm2. Neglect the effect of stress concentration.

Qus.21 Design a leaf spring for a truck to the following specifications. Maximumload on the spring = 140KN, number of springs = 4, material of springs ischrome vanadium steel, permissible tensile stress = 600 N/mm2 Maximumnumber of leaves = 10, span at spring = 1000mm, permissible deflection =80mm, young’s modulus of the spring = 200KN/mm2.


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Qus.22 A leaf spring is subjected to a total load of 140KN. The other parametersof the spring are as follows: number of springs = 4, number of leaves in each spring = 10, allowable stress = 600MPa, span of the spring = 1000mm, deflection allowed = 80mm. Young’s modulus of the spring E = 200KN/mm2. Find the thickness and width of the leaves.

Qus.23 A semi-elliptic leaf spring used for an automobile suspension consists of 3 extra full length leaves and 15 graduated leaves including the master leaf. The center to center distance between two eyes of the spring is 1 meter. The maximum force that can act on the spring is 75 kN. The ratio of width to thickness for each leaf is 9:1. The leaves are pre stressed in such a way that when the force is maximum. The stress induced in all leaves is 450 N/mm2. If modulus of elasticity is 2.07 x 105 N/mm2, Determine:

(a) The cross-section of the leaves(b) The initial nip and(c)The initial preload required to close the gap between extra fulllength and graduated leaves.

Qus.24 Design a compression spring for a safety valve for the following data. Valveopening pressure = 1N/mm2; diameter of valve sear 100mm; Shear stress = 500 N/mm2; Modulus of rigidity = 0.8 x 105 N/mm2. The spring is to be kept in a casing of 115mm ID. Maximum lift of the spring is 5mm, when the pressure is 1.08 N/mm2.

Qus.25 A truck spring has 12 number of leaves two of which is full length leaves. The spring supports are 1.05m apart and the central band is 85mm wide. The central load is to be 5.4 kN with a permissible stress 280 N/mm2. Determine the thickness and width of the steel spring leaves the ratio of the total depth to the width of the spring is 3. Also determine the deflection of the spring.

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