13. A plane of 12mm thickness with two holes as indicated in figure is subjected to tensile load of 20kN. Calculate the stresses at both the holes.

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1 UNIT - 1 PART A 1. Define: Design? 2. What is Adaptive design? Where is it used? Give examples. 3. What are the various phase of design process? 4. List some factors that influence mechanical design? 5. Explain Design for manufacture? 6. Define: Optimization? 7. What are the various optimization methods available? 8. Describe material properties hardness, stiffness, and resilience? 9. Identify the steel designed as 50 C 4 as per BIS? 10. Determine the composition of steel designed as 17 Mnl Cr 95? 11. What is an impact load? Give examples. 12. Define Principal plane, principal stress? 13. Give examples for curved beams? 14. State the difference between straight and curved beams? 15. Where will be the maximum stress developed in a curved beam? 16. Write down the formula for shear stress of a helical spring? 17. Define: Factor of safety? 18. How is factor of safety defined for brittle and ductile materials? 19. What are the various factors to be considered in deciding the factor of safety? 20. What are the factors to be considered in the selection of materials for a machine element? 21. Define stress concentration and stress concentration factor? 22. State the various methods of finding stress concentration factors. 23. Give some methods of reducing stress concentration? 24. Give one method of reducing stress concentration in key slots? 25. Differentiate between static and variable stresses? 26. What are the types of variable stresses? 27. What is meant by springs in parallel? 28. Distinguish between alternating stress and fluctuating stress? 29. What are the factors that affect notch sensitivity? 30. Explain notch sensitivity. State the relation between stress concentration factor, fatigue stress concentration and notch sensitivity. 31. Define amplitude stress and stress ratio. What is the value of stress ratio for cyclic stress?

2 32. What are the various theories of failure? 33. What is the use of Goodman & Soderberg diagrams? 34. Draw Goodman & Soderberg diagrams and locate the safe design regions? 35. Differentiate between Endurance limit and Endurance strength? 36. Define endurance limit. What are the factors affecting endurance strength? 37. Explain size factor in endurance strength? 38. What are the methods used to improve fatigue strength? 39. What is an S-N Curve? 40. What is low and high cycle fatigue? PART B 1. The piston of a reciprocating compressor has a diameter of 60mm. The maximum pressure on the piston fall is 1.25MN/mm 2 (12.5bar). Assuming the gudgeon pin passing through the small end of the connecting rod can be safely loaded in shear up to 10MN/mm 2, calculate the minimum diameter of the gudgeon pin. 2. A press working operation blanks out disk of 35mm diameter and 1.6mm thick. If the ultimate strength of the material is 200N/mm 2 and the press ram can exert a maximum force of 150kN, can be blank out five disks simultaneously in one blow. 3. A tie bar has to carry a load of 120,000N. What must be the width of the bar 3mm thick if there is a hole of 20mm diameter on its centre? Working stress of the tie bar is 75MPa. 4. An electric motor weighing 500N is mounted on a short cantilever beam of uniform rectangular cross-section. The weight of the motor acts at a distance of 300mm from the support. The depth of the section is twice the width. Determine the cross-section of the beam. The allowable stress in the beam is 40N/mm The trunnions of a mixing machine have an effective length of 30cm and the weight, which comes on each trunnions, is 12,500N. What should be the diameter of the trinnion if the fiber stress does not exceed 35N/mm 2?

3 6. The cantilever of span 500mm carries a vertical load of 6kN at free end. Assume yield value of 350MPa and a factor of safety 3. Find economic section of the cantilever among a) Circular cross-section of diameter d. b) Rectangular section of depth h and width h/t = 2. c) I section of depth 7t and flange width 5t where t is the thickness. Specify the dimension and cross-sectional area. 7. A cylindrical bar of 60mm diameter and 200mm long is fixed at one end. At the free end it is loaded as shown, with an axial load of 12kN. A downward transverse load of 5kN and a torque of 1.4kN-m. Calculate the maximum stress at the point p of the bar. 8. The cantilever of span 250mm and 50mm diameter carries a vertical load of 3kN at free end, along with a torque of 1000N-m and an axial pull of 15kN. Calculate the maximum normal stress at the top and bottom face of thefixedend. 9. A steel member is subjected to a 3D stress system and the resulting principle stresses are 120N/mm 2 80N/mm 2 and 40N/mm 2 compression. If the proportional limit of the material in simple tension is 280N/mm 2 and its poison s ration is 0.3. Determine the F.O.S according to a) Maximum principle stress theory b) Maximum principle strain theory c) Maximum shear strain theory. 10. A bolt is subjected to a tensile load of 25kN and a shear load of 10kN. Determine the diameter of the bolt according to a) Maximum principle stress theory b) Maximum principle strain theory c) Maximum shear strain theory. 11. A shaft is subjected to a bending moment vary from -200N-m to 500N- =m and a twisting moment varying from 50N-m to 175N-m. The material used has Su = 600MPa, Se = 300Mpa, Ka = 0.76, Kb =.85, Kc = 0.897, Kt = 1.85 and q = Find the diameter of the shaft by Von Mises Hencky Theory. F.O.S = A pulley is keyed to a shaft midway between two anti friction bearing the bending moment at the pulley varies from 170Nm to 510 Nm as the torsional movement in the shaft varies from 55Nm to 165Nm. The

4 frequency of the variations 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 indefinite life. The stress concentration factor for the keyway in bending and torsion may be taken as 1.6 and 1.3 respectively. Correction faction A = 1(for bending), A = 0.6(for torsion), B = 0.85, C = Use a design factor, N = A plane of 12mm thickness with two holes as indicated in figure is subjected to tensile load of 20kN. Calculate the stresses at both the holes. 14. A cantilever rod of circular section is subjected to a cyclic transverse load; varying form -100N to 300N as shown in figure. Determine the diameter d of the rod by (1) Goodman method and (2) Soderberg method using the following data. Factors of safety = 2. Theoretical stress concentration factor = 1.4. Notch sensitivity factor = 0.9. Ultimate stress = 550MPa. Yield strength = 320MPa. Endurance strength = 275MPa Size correction factor = 0.85 Surface correction factor = A transmission shaft made of C45 steel is subjected to a fluctuating torque varying from -100Nm to 500Nm. Also, a fluctuating bending moment acts on the shaft which varies from 500Nm to 500Nm. Let the stress concentration factor be 2. The shaft is machined, for a F.O.S 1.5. Determine the required diameter of the shaft. 16. A mild steel bracket is shown in the figure. It is subjected to a pull of 5000N acting at 45 0 to the horizontal axis. The bracket has a rectangular cross section is twice the thickness. Find the cross-sectional dimension of the bracket if the permissible stress in the material is 50N/mm An electric generator rotates at 200rpm and receives 300KW from the driving engine. The armature of the engine is 60cm long and is located between bearings 120cm centre to centre. The combined weight of

5 armatu8re and magnetic pull, the shaft is subjected to 9000Kg acting at right angles to the shaft. The ultimate stress to the shaft is 4480Kg/cm 2 and the shear stress is 3920 Kg/cm 2. Find the diameter of the shaft for the factor of safety 6. UNIT -2 ( PART A) 1.what is a shaft? 2.what are the types of shafts? 3.list all the shaft materials? 4.what is simple torsion? 5.what is simple bending moment? 6.write down the formula for finding equivalent twisting moment. 7.what are the types of rigidity? 8.what are the different measures followed to control the lateral deflection? 9.what arer the different ways to limit the maximum permissible transverse deflection? 10.Define the term critical speed? 11.write down the dunkerley's equation for the critical speed of the shaft? 12.what is a key? 13.what are the types of keys? 14.How are shunk keys designed? 15.what is the main use of woodruff keys? 16.list the various failures occured in shunk keys? 17.Differentiate between keys and splines? 18.what is the function of a coupling between two shafts? 19.Under what circumstances flexible couplings are used?

6 20.How is a coupling specified? 21.wher are the flexible couplings used? 22.What are the purposes in machinery for which couplings are used? 23.Name any two of the rigid and flexible couplings? 24.what is the material used for flange coupling? 25.what is the advantage of gear coupling? 26.differentiate between a cotter joint and a knucle joint. PART B 1.A 100mm dia solid circular shaft can carry a torque T without exceeding a certain max shear stress. what portion of this torque T can have a hollow shaft having a wall thickness of 10mm and same outer dia carry? Both shafts should have the same max shear stress. 2.A solid shaft is to transmit 1000kw at 120 rpm find the shaft dia if the design shear stress is 80N\mm.if the shaft is made hollow with internal dia is 0.6 times outside dia,find the % of saving in material. 3.Compare the weight,strength and stiffnes of a hollow shaft of same internal dia as that of a solid shaft.the inside dia of the hollow shaft is being 0.6times the external dia.both shafts have same material and length. 4.A hollow steel shaft of 500mm outside dia and 300mm inside dia is used to drive a propeller of a marine vessel.the shaft is mounted on bearings 6m apart and it transmits 5600kw at 150rpm.max axial thrust is 500kN and the shaft weights 70kN.Determine a)max shear stress induced. 5.A shaft is supported on bearings A and B 800mm between centres.a 20 degree spur gear having 600mm pitch dia is located 200mm and to the right of the left hand bearing A and a 700mm dia pulley is mounted 250mm

7 towards left of the bearing B.The gear is driven by a pinion with a downward tangential force while the pulley drives a horizontal belt having 180degree wrap angle. the pulley also serves as a fly wheel and weighs 2000N.The max belt tension is 3000N and the tension ratio is 3:1.Selecting suitable material for the shaft,determine the shaft dia for a factor of safety A machine shaft is supported in a bearings having their centers 750mm apart and transmits 200kw at 600 rpm.a gear of 200mm dia and 20degree tooth profile is located 250mm to the right of left hand bearing and a 450mm dia pulley is mounted at 200mm to the right of right hand bearing.the gear is driven by a pinion with a downward tangential force while the pulley drives a horizontal belt having angle of contact.the pulkey weighs 1000N and has required shaft dia for a FOS 2. 7.Aline shaft rotating at 200rpm is to transmit20 kw power.the allowable shear stress for the shaft material is 42N\mm 2.If the shaft carries a central load of 900N and is simply supported between bearings 3m apart determine the dia of the shaft.the mazx tensile or compressive stress is not to exceed 56N/mm 2. 8.A shaft carries a pulley A at left end of a spur gear B at middle of bearing supports C and D.The pulley is 1000mm in dia and gear pitch dia is 600mm.The pulley is keyed to the shaft at 400mm to the left of the left hand bearing and the distance between bearings C and D is 1250mm.The tension ratio of 3.Selecting suitable material, calculate the shaft transmits 20KW and runs at 750rpm.The shaft receives power from a motor placed vertically below the pulley through a flat belt with a ratio of tensions 2.5.The shaft delivers power to a gear placed horizontally in front.the shaft rotates in anticlockwise direction looking from left.pressure angle of gear is 20

8 degrees.design the shaft if the weight of A and B are 300N and 250N respectively and the allowable shear stress of the shaft material is 70N/mm 2,shaft and fatigue factor in bending and torsion are 2 and A solid shaft is to transmit power from an electric motor to a machine through a pulley by means of a vertical belt drive with unit speed ratio.the pulley weighs 250N and is overhanging at a distance of 120mm from the bearing.dia of pulley is 200mm.Max power transmited at 150rpm is 3KW.Coefficient of friction between a belt and the pulley is 0.25.Combined shock and fatigue factor in torsion is 1.5 and in bearing is 2,permissible shear stress for the shaft material is 40N/mm 2. Design the shaft. Standard diameters from R20 series in mm are:20,22.4,25,28,31.5,40,45,50,56,63,71 and A c45 steel shaft transmits 10KW at 750rpm. It is supported on two bearings 800mm apart and has two gears keyed on to it. The pinion having 30 teeth of 5mm module is located 120mm to the left of the right hand bearing and delivers power horizontally to the right.the gear having 100 teeth of 5mm module is located 150mm to the right of the left hand bearing and recives power(ccw viewed from the left end) from below. Determine the dia of the shaft. 11.A 600mm dia pulley driven by a horizontal belt transmits power through a solid shaft to a 262mm dia pinion which drives a matting gear.the pulley weighs 1200N to provide some fly wheel effect.the arrfangement of elements, the belt tensions and the components of the gear reactions on the pinion are as indicated in the fig.determine the necessary shaft dia using a suitable value for commercial shafting and shock fatigue factors of K b =2 and Kt=1.5

9 12.Power is transmitted to a shaft supported on bearings, 900mm apart by a belt drive, running on a 450mm pulley which overhangs the right berings by 200mm.Power is transmitted from the shaft through a belt drive,running on a 250mm pulley,located midway between the bearings.the belt drives are at right angle to each other and the ratio of belt tension is 3;with the max tension in both the belts being limited to 2KN.Determine the dia of the shaft,assuming permissible tensile and shear stress are 100Mpa and 60Mpa. 13.A shaft is to transmit 50KW at 1200rpm.It is also subjected to a bending moment of 275Nm.Allowable shear stress is 60N/squ.mm.The shaft is not to twist more than 2 degree in length of 2m.G=80*10^3N/squ.mm.Design the shaft. 14.Design a muff coupling to connect two shafts tyransmiting 40KW at 150rpm.The allowable shear and crushing stress for the shaft and the key are 37N/squ.mm and 96.25N/squ.mm.The permissible shear stress for the muff is 17.5N/squ.mm.Assume that max torque transmitted is 20% more than the mean torque.take the width and depth of the parallel key is 22mm and 14mm. 15.A rigid type of coupling is used to connect two shafts transmiting 15KW at 200rpm.The shaft, keys and bolts are made of C-45 steel and the coupling is of cast iron.design the coupling. 16.The split muff coupling is to be designeds to transmit 67.5KW at 180rpm.Determine the dia of the solid shaft if permissible shear stress in the shaft material is limited to 42Mpa.Assuming that the two halves of the coupling are connected by 8 bolts, determine the dia of each clamping bolt if the permissible tensile stress intensity for the bholt material is limited to 70N/squ.mm.The coefficient of friction Is 0.3.

10 17.Two shafts 100mm dia are to be connected by meansa of cast iron coupling.the allowable shearing stress of the bolt material is 45N/squ.mm.While that of the shaft material is 55N/squ.mm.Find the size of the bolts to be used.check the bolts for the indused crushing stress. 18.Determine the dimensions of flange coupling that connects a motor and a pump shaft.the power to be transmitted a 2KW at a shaft speed of 960rpm.select suitable materials for the parts of the coupling and list the dimensionms. 19.Design a protected type flange coupling for the following requirements:power to be transmitted=10kw.speed of the shaft =960rpm.Select the suitable material. 20.Design and sketch a protective type cast iron flange coupling to transmit 10KW at 250rpm.Take permissible shear stress for key, shaft and bolt as 50N/squ.mm.Take crushing stress of key as 90N/suq.mm and shear stress cast iron as 14N/squ.mm.Assume max torque is 30% higher than mean torque. 21.A marine type flange coupling is used to transmit 3.75MW at 150rpm.The allowable shear stress in the shaftb and bolts maqy be taken as 50N/squ.mm.Determine the shaft dia and the dia of the bolts as per indian standard. 22.Design and sketch a flexible flange coupling to transmit 5KW at 750rpm with a service factor of 1.2.For shaft, bolt and key permissible shear stress 50N/squ.mm.For cast iron shear stress is 15N/qsu.mm and bearing stress for bush is 2N/squ.mm.For key crushing stress is 100N/squ.mm. 23.Design a bushed pin type of flexible coupling for connecting a motor and a pump shaft for the following data Power=20KW.

11 Speed=1000rpm. Shaft dia =50mm Bearing pressure for rubber bush=0.3n/squ.mm. 24.A knuckle joint is to transmit a force of 140KN.Allowable stress in tension,shear and compression are 75N/squ.mm,65N/squ.mm and 140N/squ.mm.Design the shaft. 25.A pin in a knuckle joint is subjected to an axial load of 90KN.Assume that the thickness of the eye is to be 1.5 times the dia of the pin.the allowable stress of the material in tension and compreesion is due to bending is 60Mpa and allowable stress in shear is 30Mpa.The allowable bendintg stress is 20Mpa.Determine the required pin dia. UNIT-3 (PART-A) 1. What are the purposes of screws? 2. Define pitch, lead? 3. List some types of commonly used thread forms? 4. How is a bolt designated? 5. State the advantages of coarse threads? 6. State the advantages of threaded joints? 7. What are the differential and compound screws? 8. What are the advantages of preloading? 9. What factors influence the amount of initial tension? 10. What is bolt of uniform strength? 11. What are the ways to produce bolts of uniform strength? 12. What stresses act on screw fastenings? 13. Define the term self-locking of power screws? 14. Define welding? 15. Why are welded joints preferred to over riveted joints? 16. How is welding classified? 17. How is forged welding performed? 18. State something about electric resistance welding? 19. State the main principle of fusion welding?

12 20. What are the general applications of welding? 21. What are the advantages of welding? 22. State the limitations of welding? 23. What are the types of welded joints? 24. Define butt and lap joints? 25. Define tee joint and corner joint? 26. Define edge joint? 27. State the weld symbols for double U-joint and single V-joint? 28. State the types of forces involved while designing? 29. When will the edge preparation need? 30. Write down the formula for tensile strength of a double V-groove butt joint? 31. What are the two types of fillet weld? 32. Write down the formula for strength of fillet and double fillet? 33. Write down the formula for the strength of single transverse fillet weld? 34. Differentiate with a neat sketch the fillet welds subjected to parallel loading and transverse loading? 35. Write down the formula for the strength of the combination of single transverse and fillet welds? 36. When will the weld deposit be weaker? 37. Define eccentrically loaded welded joints? 38. What are the two types of stresses are induced in eccentric loading of loaded joint? 39. State the two types of eccentric welded connections? 40. Write down the formula for maximum shear stress according to maximum stress theory? 41. What is the stress concentration factor? Where does it occur? 42. What are the significances of welding specification? 43. What are the main indications of complete weld symbol? PART-B 1. A plate 100mm wide and 12.5mm thick is to be welded to another plate by means of two parallel fillet welds. The plates are subjected to a load of 50KN. Find the length of the weld so that the maximum stress does not exceed 56N/sq.mm. (Do the calculations under static loading). 2. A plate 100mm wide and 12.5mm thick is to be welded to another plate by means of single transverse and double parallel fillet welds.

13 Determine the length of weld run in each case, if the joint is subjected to varying loads. The recommended design stress in tension is not exceed 70N/sq.mm and in shear 56N/sq.mm for static loading. 3. A bracket of width 35mm is welded to a machine frame as shown in fig. the maximum load on the bracket is 1 ton. Find the size of the weld at the top and bottom of the bracket. 4. A bracket shown in fig carries a load of P. Calculate the value of P, if the weld size is 15mm and the allowable stress is not to exceed 80N/sq.mm. 5. A bracket shown in fig carries a load of 10KN. Find the size of the weld if the allowable shear stress is not to exceed 75N/sq.mm. 6. A plate of 200mm width and 600mm long is welded to a vertical plate by placing it on the vertical plate to form a cantilever with projecting length of 480mm and overlap between the plates as 120mm. Fillet weld is done on all three sides. A vertical load 30KN is applied at the free end of the cantilever plate parallel to its width of 200mm. If the allowable weld stress is 95MPa.Determine the weld size. 7. A circular bar of 50mm diameter and 200mm long is welded to a steel plate. It supports a vertical downward load of 10KN at its free end. Determine the weld size assuming the strength of the weld to be 94MPa. 8. A rectangular beam is to be welded to a plate. The maximum load of 14KN is applied repetitiously. Determine the size of weld required for 10,000, 000 cycles. Assume the shear load is distributed uniformly over the entire weld. Refer fig shown below. 9. An eccentrically loaded plate is welded to a frame as shown in fig. Design the welded joint. If the tensile stress in the plate should not exceed 100N/sq.mm and that in weld is 80N/sq.mm. 10. A plate 100mm wide and 12.5mm thick is to be welded to another plate by means of two parallel welds. The plates are subjected to a load of 50KN. Find the length of the weld so that the maximum stress does not exceed 56N/sq.mm. (Do the calculation under static welding).

14 UNIT - 4 (PART A) 1. What is a spring? 2. What are the applications of spring? 3. State any two functions of springs? 4. What are the various types of springs? 5. Classify the helical springs? 6. How will you find whether the given helical spring is a compression spring or tension spring? 7. Define leaf springs? 8. Define: Belleville Springs? 9. What are conical springs? 10. What is spring index? or Define the term spring rate? 11. What are active coils? 12. What are inactive coils? 13. What is a pitch? 14. What is solid length? 15. What are the requirements of spring whiled designing? 16. Write down the formula for shear stress of a helical spring? 17. Write down the formula for shear stress correction factor? 18. What is shear stress correction factor according to the Wahl s hypothesis? 19. Write down the formula for deflection of helical spring? 20. What is stiffness of spring (q)? 21. Define: Energy stored in springs? 22. What are the end conditions of springs? 23. What are the disadvantages of springs? 24. What is buckling of springs? 25. What is surge in springs? 26. Write down the formula for natural frequency of spring? 27. What is meant by springs in parallel? 28. What is meant by springs in series? 29. When two concentric springs of stiffness 100N/mm and 50N/mm respectively are subjected to an axial load of 750N, what will be the deflection of each spring? 30. For springs in series, the spring rates (stiffness) add reciprocally. Prove. 31. Define surging of springs?

15 32. What are the various spring materials? 33. What are the different groups according to service conditions? 34. How concentric springs are obtained? 35. State the springs index for concentric springs? 36. What is Belleville springs? 37. State the advantage of leaf spring over the helical spring? 38. Write down the formula for bending stress and deflection? 39. Write down the formula for maximum stress & deflection of cantilever spring and supported spring? 40. What is a laminated leaf spring? 41. What are semi-elliptical springs? 42. What is nipping of laminated spring? Discuss its role in spring design? 43. Why Wahl s factor is to be considered in the design of helical compression springs? 44. What is lever? 45. Mention any four basic terms involved while designing levers? 46. Classify levers? 47. Give the section for the following sections? (i) Rectangular. (ii) I-secton. 48. Write down the formula of section modulus for circular hollow section? 49. What are the factors to be considered for designing fulcrum pin of the lever? 50. State the general uses of hand levers? 51. What are the uses of foot levers? PART B 1. A compression helical spring is required to exert a minimum force of 250N and maximum force of 600N and the deflection for this change in load is to be 15mm. The spring must fit in a hole of 30mm diameter. The load is static. Ultimate tensile stress is 1393MPa and shear stress is 606MPa?

16 2. A solenoid brake is to be actuated by a helical compression spring. The particle should have a free length of approximately 450mm and is to exert a maximum force of 14000N when compressed to a length of 375mm. The outside diameter must not exceed 175mm. Selecting suitable material, design the spring. 3. A helical spring is subjected to a load varying from 400N to 100N having an index of 6 and the design factor of safety is The compression of the spring at the maximum load is 30mm. Design the helical compression spring. Take yield shear as 110N/mm 2, endurance stress in shear as 350N/mm 2 and the modulus of rigidity for the spring material as 80 x 10 3 N/mm A load of 2kN is dropped axially on a closed coil helical spring from a height of 250mm. The spring has 20 effective turns and it is made of 25mm diameter wire. The spring index is 8. Find the maximum shear stress induced and the amount of compression produced. Modulus of rigidity may be taken as 84kN/mm An automobile semi-elliptical spring is 1.5 long carries a load of 8000N. The spring consists of 10 leaves with 2 full-length leaves. All leaves are 50mm wide. Find the thickness of leaves. Also find the maximum stress induced for a deflection of 60mm. 6. A semi-elliptic spring used for automobile suspension consists of two extra full-length leaves and eight graduated leaves. The maximum spring load 30kN and has an effective length of 1.2m. The leaves are made of 55 Si Mo 90 which has a yield strength of 1500N/mm 2 and E = 2.1 x 10 5 N/ mm 2. The factor of safety is assumed to be 2. The leaves are pre-stressed so as to equalize stresses in leaves under maximum load. Determine the dimensions of the cross-section of the leaves and the deflection at the end of the spring. 7. Design a leaf spring for a truck of the following specifications. Maximum load on the spring 140kN Number of springs 4 Material for construction Chromium Vanadium Steel Permissible tensile stress 600N/mm 2 Maximum number of leaves 10 Span of spring 1000mm

17 Permissible deflection 80mm Young s Modulus of the spring 200kN/mm 2 8. Design a cantilever spring to absorb 600N-m energy without exceeding a deflection of 150mm and a stress of 800N/mm 2.The length of the spring is 600mm.The material of the spring is steel. 9. A leaf spring for a small trailer is to support a load of 8kN. The spring has 8 graduated leaves and extra full-length leaves of spring steel for a safe stress 380MPa.The overall length is 1m and the external band is 80mm wide. Taking the ratio of total depth of leaves to width as 3, design the spring. 10. A safety valve of 60mm diameter is to blow off at a pressure of 1.2N/mm 2. It is placed on its seat by a close coiled helical spring. The maximum lift of the valve is 10mm. Design a suitable compression spring of spring index 5 and providing an initial compression of 35mm. The maximum shear stress in the material of the wire is limited to 500N/ mm 2.The modulus of rigidity for the spring material is 0.80x10 5 N/ mm 2.Calculate (i) Diameter of the spring wire. (ii) Main coil diameter (iii) Number of active turns (iv) Pitch of the coil 11. A relief valve must blow off at a pressure of 1.22MPa and should lift by 6mm for a 6% increase in pressure. The valve diameter is 65mm. Take the spring index as 8. Maximum allowable shear stress of the material is 600N/mm 2. The diameters of the available spring wires in mm are 13, 14, 15 and 18. Modulus of rigidity is 81370N/mm 2. Consider Wahl s factor. Take inactive number of turns as 1. Design the valve spring. 12. A helical spring whose mean diameter is 8 times that of the wire is to absorb 400N-m of energy. The initial compression of spring is 50mm and it compress by additional 70mm while absorbing shock. The maximum allowable stress is 400MPa and G = 84 x 10 3 MPa.Determine the diameter of wire and number of turns.

18 13. One helical spring is nested inside another; the dimensions are as tabulated below. Both the spring have same free length and a total load of 2500N. Elements Outer spring Inner spring Number of active coils 6 10 Wire diameter 12.5mm 9mm Mean coil diameter 100mm 70mm Determine: (i) (ii) (iii) Maximum load carried by each spring. Total deflection of each spring Maximum stress in each spring. Take, G = 83BPa. 14. A spring loaded safety valve for a boiler is required to blow-off at a pressure of 1.5N/mm 2. The diameter of the valve is 60mm. Diameter of the valve is 60mm. Design a suitable compression spring for the safety valve, assuming spring index to be 6, and 25mm initial compression. The maximum lift of the valve is 15mm. The shear stress in the spring material is to be limited to 450MPa. Assume the value of G = 0.84x 10 5 MPa. 15. A semi-elliptic leaf spring is of 1m long and is required to resist a load of 50kN. The spring has 15 leaves, of which three are full length leaves. The width of central band is 100mm. All the leaves are to be stressed to 420MPa. The ratio of total depth to width is 3. Take E = 2.1 x 10 5 MPa. Determine (i) The thickness and width of the leaves. (ii) The initial gap that should be provided between the full length and graduated leaves before assembly and (iii) The load exerted on the band for the assembly. 16. A locomotive spring has an overall length of 1.1m and sustains a load of 75kN at its centre. The spring has 3 full-length leaves and 15 graduated leaves with a central band 100mm wide. All leaves are to be stressed to 420N/mm 2 when fully loaded. The ratio of the spring depth to width is to be approximately 2. Take E = 2.1 x10 5 N/mm 2. (i) Determine width and thickness of the leaves.

19 (ii) Determine the initial space that should be provided between the full length and graduated leaves before the band load is applied. (iii) What load is exerted on the band after the spring is assembled? UNIT - 5 (Part A) 1.what is the nature of contact involved in a ball bearing element? 2.Define antifriction bearings. 3.what are the types of rolling contact bearings? 4.State the components of rolling contact bearings. 5.what are the several types of radial ball bearings? 6. what are the types of thrust ball bearings? 7.Classify the roller bearings. 8.Define the term bearing life. 9.Write down the formula for calculating the reliability of bearing. 10.What is load rating? 11.What is basic static load rating? 12.Explain the term dynamic load carrying capacities of rolling contact bearing. 13.How can be the equivalent bearing loads computed? 14.Write down the typical formula for calculating the load life relationship. 15.State any points to be considered for selection of bearings. 16.What is bearing? 17.Classify the types of bearings? 18.List any six types of bearings materials.

20 19.What are the required properties of bearing materials? 20.What is a journal bearings? 21.What are the types of journal bearings depending upon the nature of contact? 22.What are the types of journal bearings depending upon the nature of lubrication? 23.What is known as selfacting bearings? 24.State the theory of lubrication? 25.What are the terminologies used in designing of journal bearings? 26.Define kinematic viscosity. 27.What is bearing characteristics number? 28.How is sommerfield number calculated? 29.Write down the formula to calculate the heat generated and heat dissipated in journal bearings. 30.What is critical pressure? 31.What is flywheel? 32.What is the function of flywheel? 33.What are the applications of flywheel? 34.State any two types of flywheel. 35.What is flywheel effect? 36.Define coefficient of fluctuations of speed in case of flywheels. 37.Define the term fluctuation of energy. 38.Is there any relations between the coefficient of fluctuations of energy and coefficient of staediness? 39.State the type of stresses induced in a rim flywheel. 40.What are the stresses induced in flywheel arms?

21 41.Write down the formula for the maximum torque that can be transmitted by the flywheel of solid and hollow shaft. 42.How does the function of flywheel differ from that of governor? PART - B 1.Design a journal bearing for a centrifugal pump running at 1440rpm.Diameter of the journal os 10cm and the load on each bearing is 2000kg.The factor (Zn)/p may be taken as 2800.For centrifugal pump bearings: Assume Atmospheric temperature=30deg Operating tempereture=75deg Energy dissipation co-efficient= C/R ratio=0.001 L/D ratio=1.5 2.A single cylinder I.C. engine working on four-stroke cycle develops 75kW at 360rpm.The maximum fluctuation of energy can be assumed to be 0.9 times the energy developed/cycle.if the total fluctution of speed is not to exceed 1% and the maximum centrifugal stress in the flywheel is to be 5.5N/m 2 estimate the mean diameter and cross-sectional area of the rim.flywheel is made of cast iron. 3.Determine the maximum tensile stress in the thin of a steel flywheel rotating at 600rpm.The mean radius of rim is 1500mm.The flywheel rim is 200mm thick and 300mm wide.the area of cross setion of the rim is 0.06m 2 and each of the six spokes is constant in cross section area of 0.01m 2.Find also stress in each spoke.

22 4.Design and sketch a C.I flywheel for four-stroke C.I. engine developing 50kW at 150rpm with 75 explosions per min. The total fluctuation of speed is limited to 0.5% of the mean speed on either side. The work done during working stroke is 1.4 times the work done during the cycle. Assume flywheel stores 90% of energy on the rim, hoop stress on the rim should not increase more than 4N/mm 2 and density of the material is 7200kg/m 3. 5.A four stroke single cylinder gas engine runs at a constant load and delivers 25KW at 300rpm. The maximum fluctuation of energy per cycle may be taken as 0.6 times the useful work per cycle.design a suitable rim flywheel of rectangular section to limit the variation of speed during the cycle to + or 2% of the mean speed. The flywheel is made of cast iron. 6.Design a rim type C.I flywheel for an I.C engine to store 10,000N-m of energy. The speed of engine is to be 500+ or -2.5%.Assume suitable stress value. 7.Design a rim type C.I. flywheel for a four-stroke engine to the following data. Power=75kW; Speed =250rpm; fluctuation of speed = +or -2.5% work done during power stroke is 30% higher than average work done during whole cycle.for shaft,allowable shear stress is 45N/mm 2. 8.A cast flywheel at 500rpm is to furnish 100kNcm energy during 0.1 revolutions. The total fluctuation of speed 10%. Design the flywheel and find the power rating of the motor to drive the machine. 9.Design a cast iron flywheel to stroke 7kNm of energy to keep the between 306 and 294rpm outside diameter of flywheel is not to be more than 1.5m. Design the rim and arms of the flywheel. Power developed by the machine is 20kW. Maximum torque=1.5 times the mean torque. 10.A multi cylinder engine is to run at a constant load at a speed of 500rpm on drawing the crank effort diagram to scale of 1cm=2500Nm and

23 1cm=60deg, the area above and below the mean torque line were measured and found to be in order +1.60, -1.72, +1.68,-1.91 and If the speed is to be kept with in limits of +1% of the mean speed, design the suitable type of flywheel. 11.A ball bearing is rated by manufacture to have an average life of 1000hrs when carring aload of 45N at 1800rpm. 1)What is the 90% life expectancy for this bearings?2) What is rated load capacity of this bearing for an average life of 50,000hrs at 1800rm? 12.Select a suitable ball bearing for a drilling machine spindle of dia 40mm rotating at 3000rpm. It is subjected to a radiale load of 2000N and axial thrust of 1000N.It is t o work for 45hrs a week for one year. 13.Select a suitable Conrad type deep groove ball bearing for the following data, the radial load is 7500N and axial load is 4500N, the shaft speed is 2000rpm, the L 10 life required is 4.9 *10 8 revolutions; the inner ring of the bearing rotates. 14. A Sleeve bearing is 10mm in dia and 10mm long. SAE 10 oil at an inlet temperature 50 deg is used to lubricate the bearing. The radiale clearance is mm. If the journal speed is 3600rpm and the radial load on the bearing is 68N, Find the temperature raise of lubricant and the minimum flim thickness. 15. Following data is given for a 360deg hydrodynamic bearing: Journal dia=100mm Radial clearance=0.12mm Radial load=50kn Bearing length=100mm Journal speed=1440rpm Viscosity of the lubricant=16cp

24 Calculate 1) minimum film thickness, 2) Co-efficient of friction and 3) Power lost in friction. 16. Design a journal bearing for a centrifugal pump to the following specification: Dia of the journal=75mm Speed of the journal=1140rpm Load on each journal=11500n. 17. A single cylinder double acting steam engine delivers185kw at 100rpm. The max fluctuation of energy per revolution is 15% of energy developed per revolution. The speed variation is limited to 1% either way from mean. The mean dia of the rim is 2.4m. Design the cast iron flywheel for the engine. 18. Design a C.I. flywheel for a four-stroke engine developing 150kW at 200rpm. Calculate the mean dia of the flywheel if hoop stress is not to exceed 4Mpa. Total fluctuation of speed is to be 4% of mean speed. Work done during power stroke is 1.5 times average work done during the cycle. Density of CI is 7200kg/m 3.