UNIT 1STEADY STRESSES AND VARIABLE STRESSES IN MACHINEMEMBERSSYLLABUSSTEADY STRESSES AND VARIABLE STRESSES IN MACHINE MEMBERS 9Introduction to the design process - factor influencing machine design,selection of materials based on mechanical properties - Direct, Bending and torsionalstress equations -Impact and shock loading - calculation of principle stresses forvarious load combinations, eccentric loading - Design of curved beams - crane hookand 'c' frame - Factor of safety -theories of failure - stress concentration - design forvariable loading - Soderberg, Goodman and Gerber relationsPART A1. What is meant by design?[NOVEMBER/DECEMBER 2005/1]Design: Design is nothing but a series of activities to gather all the informationnecessary to realize the designer's idea as a real product.2. With a block diagram show the various stages of Design processes.[MAY/JUNE2006/2][NOVEMBER/DECEMBER2006R/1]a. Recognition of need.b. Definition of problemc. Synthesisd. Analysis and optimizatione. Evaluationf. Presentation3. What factors should be considered in machine design?[NOVEMBER/DECEMBER 2005/2]Factors to be considered in Machine Design: (Any four)Type of Load and stresses caused by the load.Motion of the parts of kinematics of the machine.Selection of materials.Page 1 of 24Form and size of the parts.Frictional resistance and lubrication.Convenient and economical factors.Use of standard parts.Safety operation.Environment factors.Cost considerations.Quantity and quality required.Assembly requirement, etc.4. Sketch the stress-strain diagram for a ductile specimen and indicate its salientfeatures.[MODEL QUESTION PAPER/1]5. How the allowable stress is estimated in (a) ductile material (b) brittle material?[NOVEMBER/DECEMBER'2004/3]6. What is factor of safety?[NOVEMBER/DECEMBER 2005/3]Factor of safety: The ratio between maximum stresses to working stress is known asfactor of safety.7. List out the factors involved in arriving at factor of safety.[APRIL/MAY 2005/4]8. List the important factors that influence the magnitude of factor of safety.[MAY/JUNE 2007/2]9. Explain the normal stress theory and its limitation.[MAY/JUNE 2006/1]10. State maximum shear stress theory of failure.[NOVEMBER/DECEMBER'2004/1]11. State St. Venant theory of failure.[NOVEMBER/DECEMBER 2006R/2]12. What is stress concentration factor?[APRIL/MAY 2005/3]Stress concentration factor is the ratio of maximum stress at critical section to thenominal stress.13. With sketch show any two ways of reducing stress concentration factor.[MAY/JUNE 2006/3]14. Name any two sources of stress concentration in machine elements.Page 2 of 24[NOVEMBER/DECEMBER'2004/2]15. Define variable load.[NOVEMBER/DECEMBER 2005/4]If the load changes either in magnitude or direction or both, it is called live or variableload. Load varies with time is also called variable load.16. Differentiate between fluctuating, alternating and reversed stress bydiagrams.[APRIL/MAY 2005/5]17. Define 'endurance limit' in design[MODEL QUESTION PAPER/3]Endurance limit is the maximum value of completely reversed stress that the standardspecimen can sustain an infinite number (10) of cycles without failure.718. What are the common materials used in mechanical engineering Design? How canthe properties of steel be improved?[MAY/JUNE 2007/1]PART BTheory19. What is factor of safety? List the factors to be considered while deciding the factor ofsafety. (6)[NOVEMBER/DECEMBER2006R/11a(ii)]20. Define the terms "equivalent torque and equivalent moment". (4)[NOVEMBER/DECEMBER 2006R/11b(ii)]DIRECT, BENDING AND TORSIONAL STRESS EQUATIONS21.Alead of 5 KN is to be raised by means of a steel wire. Find the minimumdiameter required, if the permissible stress in the wire is not to exceed 100N/mm(4 Marks)[MODEL QUESTION PAPER/11(i)]222. A circular shaft is to transmit a torque of 500 N-mm at a speed of 1000 rpm.Find out the diameter of the shaft, if the permissible shear stress in the shaftmaterial is 70 N/mm.(6 Marks)[MODEL QUESTION PAPER/11(iii)]2Page 3 of 24

23. A square bar of 20 mm x 20 mm in section is subjected to a bending moment of1000 N-mm. Calculate the stress induced in the top and bottom fibers of the bar.What will be stress in the above fibers, if the bar is additionally acted upon by atensile stress of 50 N/mmalong the axis?(6 Marks)[MODEL QUESTION2PAPER/11(ii)]24. The piston of a reciprocating compressor has a diameter of 60 mm. Themaximum pressure on the piston fall is 1.25 MN/massuming the gudgeon pin2passing through the small end of the connecting rod can be safely loaded inshear up to 10 MN/m, calculate the minimum diameter of the gudgeon pin.2[NOVEMBER/DECEMBER 2005/12b]25. A hollow shaft of 40 mm outer diameter and 25 mm inner diameter is subjected to atwisting moment of 120 N-m, simultaneously, it is subjected to an axial thrust of 10k.N and a bending moment of 80 N-m. Calculate the maximum compressive andshear stresses.(12)[NOVEMBER/DECEMBER 2006R/11b(i)]26. A mild steel bracket is shown in figure 1. It is subjected to a pull of 5000 Nacting at 45 to the horizontal axis. The bracket has a rectangular sectionwhose depth is twice the thickness. Find the cross sectional dimensions of thebracket if the permissible stress in the material is 50 N/mm.2[NOVEMBER/DECEMBER 2005/12a]Fig. 1THEORIES OF FAILURE27. In an elastic material, principal stresses are tensile and compressive andthe ratio being 4 : 1. Determine the limiting stress according to differenttheories of failure if tension test gives elastic limit of the material as400 N/mm. Assume Poisson's ratio as 0.3.[APRIL/MAY 2005/12a]228. A bolt is subjected to a direct load of 25 kN and shear load of 15 kN. Consideringvarious theories of failure, determine a suitable size of the bolt, if the material of thePage 4 of 24

bolt is C 15 having 200 N/mmyield strength. (6)2[MAY/JUNE 2007/11a(ii)]STRESS CONCENTRATION29. A plate of 12 mm thick, with two holes as indicated in Fig. 2 is subjected to tensileload of 20 kN. Calculate the stresses at both the holes.[NOVEMBER/DECEMBER'2004/12a]Fig. 230. Determine the maximum stress involved in the following cases takingstress concentration into accountCase(i) a rectangular plate with a hole under an axial load of 10 kN(ii) a circular shaft with a step under an axial load of 10 kN(iii) a shaft under a bending moment of 50 Nm(iv) a shaft under a twisting moment of 50 Nm.[APRIL/MAY2005/12b]VARIABLE LOADING26.A bar of circular cross section is subjected to alternating tensile forces varyingfrom a minimum of 200 kN to maximum of 500 kN. It is to be manufacturedfrom a material with an ultimate tensile strength of 90 MPa and an endurancelimit of 70 MPa. Determine the diameter of the bar using safety factors of 3.5 inultimate tensile strength and 4 in endurance limit strength and stressconcentration factor of 1.65 for fatigued load. Use Goodman relation for thebasis of design.[MODEL QUESTION PAPER/12(b)]26. A cantilever rod of circular section is subjected to a cyclic transverse load; varyingfrom -100 N to + 300 N as shown in Fig. 3. Determine the diameterdof the rod by(i)Goodman method and(ii) Soderberg method using the following data.Page 5 of 24

Factor of safety =2.Theoretical stress concentration factor =1.4Notch sensitivity factor =0.9Ultimate strength =550 MPaYield strength =320 MPaEndurance strength =275 MPaSize correction factor =0.85Surface correction factor =0.9.[NOVEMBER/DECEMBER'2004/12b]fig.328. A cantilever beam made of steel Fe 540 (Sut = 540 N/mm2 and Syt = 320N/mm2) issubjected to a completely reversed load (P) of 5 kN is shown in Fig 4. The shaft ismachined and the reliability is 50%. The factor of safety is 2 and the notch sensitivityfactor is 0.9. Calculate(i) Endurance strength at the fillet section and(ii) Diameter'd'for infinite life.[MAY/JUNE 2006/13b]Fig 428. A transmission shaft made of C45 steel is subjected to a fluctuating torque varyingfrom - 100 N-m to +500 N-m. Also, a fluctuating bending moment acts on the shaft,which varies from +500 N-m to -500 N-m. Let the stress concentration factor be 2;The shaft is machined, for a factor of safety of 1.5. Determine the required diameterof the shaft.[NOVEMBER/DECEMBER 2005/13a]Page 6 of 2428. A bar of circular cross-section is subjected to alternating tensile forces varying from aminimum of 200 kN to a maximum of 500 kN. It is to be manufactured of a materialwith an ultimate tensile strength of 900 MPa and an endurance limit of 700 MPa.Determine the diameter of bar using safety factors of 3.5 related to ultimate tensilestrength and 4 related to endurance limit and a stress concentration factor of 1.65 forfatigue load. Use Goodman straight line as basis for design. (16)[MAY/JUNE 2007/11b]31. Determine the thickness of a 120 mm wide uniform plate for safe continuousoperation if the plate is to be subjected to a tensile load that has a maximum value of250 kN and a minimum value of 100 kN. The properties of the plate material are asfollows. Endurance limit stress is 225 MPa and Yield point stress is 300 MPa. Thefactor of safety based on yield point may be taken as 1.5. (10)[NOVEMBER/DECEMBER 2006R/11a(i)]UNIT 2DESIGN OF SHAFTS AND COUPLINGSPage 7 of 24SYLLABUSDESIGN OF SHAFTS AND COUPLINGS 10Design of solid and hollow shafts based on strength, rigidity and critical speed Designof keys, key ways and splines - Design of crankshafts -- Design of rigid and flexiblecouplings.DESIGN OF SHAFTSPart A1.Differentiate between shaft and axle.[APRIL/MAY 2005/10]2. State any two reasons for preferring hollow shaft over solid shaft.[NOVEMBER/DECEMBER' 2004/7]3. What is the critical speed of shaft?[APRIL/MAY 2010R/4]4. What is Jack shaft?[APRIL/MAY 2010R/3]5. How is the strength of a shaft affected by the keyway?[APRIL/MAY 2007R/3]6. Why is maximum shear stress theory used for shaft?[NOV' 2009/3]7. What is the significance of slenderness ratio in shaft design?[NOV' 2008/3]8. Why a hallow shaft has greater strength and stiffness than solid shaft of equal weight?[APRIL/MAY 2008R/3]Part B1. A Shaft transmits 20 kW power and rotates at 500 rpm. The material of shaft is 50C4and the factor of safety is 2. (1) Determine the diameter of shaft on the basis of itsshear strength. (2) Determine the diameter of shaft on the basis of its torsional rigidity,if the permissible angle of twist is 3 per meter length and modulus of rigidity of shaftmaterial is 79300 N/mm.(10)[ APRIL/MAY 2007R/11a(i)]22. A turbine shaft transmits 500 kW at 900 rpm. The permissible shear stress is 80N/mmwhile twist is limited to 0.5 in a length of 2.5 m. Calculate the diameter of2Page 8 of 24shaft. Take G = 0.8 X 105 N/mm. If the shaft chosen is hollow with d/ d= 0.6.2ioCalculate the percentage of saving in material. (10)[ APRIL/MAY 2007R/12a(i)]3.A solid shaft of diameter 'd' is used in power transmission. Due to modification ofexisting transmission system, it is required to replace the solid shaft by a hollow shaftof the same material and equally strong in torsion. Further, the weight of hollow shaftper meter length should be half of the solid shaft. Determine the outer diameter ofhollow shaft in terms of d.[NOV' 2009/12a]4.A shaft is to transmit 50 kW at 1200 rpm. It is also subjected to abending moment of 275 N-m. Allowable shear stress is 60 N/mm. The shaft is2not to twist more than 2 in a length of 2m. G = 80 X 10N/mm.32Design the shaft.[NOVEMBER/DECEMBER 2005/15a][NOVEMBER/DECEMBER 2006R/12a]5.A solid circular shaft is subjected to a bending moment of 3000 N-m and a torque of10000 N-m. The shaft is made of 45C8 steel having ultimate tensile stress of 700 MPaand a ultimate shear stress of 500 MPa. Assuming a factor of safety as 6, determine thediameter of the shaft.[APRIL/MAY 2009R/12a]6. Design a hollow shaft to transmit 25 hp at 300 rpm. The loading is such that themaximum bending moment is 1000 Nm the maximum torsional moment is 500 Nmand axial thrust is 15 kN. The shaft is supported on rigid bearings 1500 mm apart. Theinside diameter of the shaft is 0.8 times the outside diameter. The load is cyclic innature and applied with shocks. The values of shock factors are C= 1.5 and Cm =11.6.[NOV' 2008/12a]7. A mild steel shaft transmits 23 kW at 200 r.p.m. It carries a central load of 900 N andis simply supported between the bearings 2.5 metres apart. Determine the size of theshaft, if the allowable shear stress is 42 MPa and the maximum tensile or compressivestress is not to exceed 56 MPa. What size of the shaft will be required, if it is subjectedto gradually applied loads?[NOV' 2007/12a]8.A line shaft supporting two pulleys A and B is shown in Figure 1. Power issupplied to the shaft by means of vertical belt on pulley A, which is thentransmitted to pulley B carrying a horizontal belt. The ratio of belt tensions ontight and loose sides is 3 : 1 and the maximum tension in either belt is limited to2.7 kN. The shaft is made of plain carbon steel 40C8 (S= 650 N/mmand Syt =2ut380 N/mm. The pulleys are keyed to the shaft. Determine the shaft diameter2according to the A.S.M.E. code if.k=1.5 andk=1.0.[MAY/JUNE 2006/11]btPage 9 of 24

fig.19. A shaft is supported by two bearing arranged 1 m apart, A 600 mm diameterpulley is mounted at a distance of 300 mm to the right of the left hand bearingand this drives a pulley directly below it with the help of a belt having maximumtension of 2.25 kN. Another pulley of 400mm diameter is placed 200 mm to theleft of the right hand bearing and is driven with the help of an electric motor and abelt, horizontally to the right. The angle of contact for both the pulley is 180and the coefficient of friction is 0.24. Design the diameter of the solid shaft,allowing a working stress of 60 N/mmin tension and 40 N/mmin shear for the22material of the shaft. Assume the torque input & torque output are equal.[MODEL QUESTION PAPER/11(iii)] [MAY/JUNE 2010/12a]10. Power is transmitted to a shaft supported on bearings, 900 mm apart, by abeltdrive, running on a 450 mm pulley, which overhangs the right bearing by 200mm. Power is transmitted from the shaft through a belt drive, running on a 250mm pulley, located mid-way between the bearings. The belt drives are at rightangle to each other and the ratio of belt tensions is 3; with the maximum tensionin both the belts being limited to 2 kN. Determine the diameter of the shaft,assuming permissible tensile and shear stresses are 100 MPa and60 MPa respectively.[NOVEMBER/DECEMBER' 2004/11]DESIGN OF KEYS, KEY WAYS AND SPLINESPage 10 of 24COUPLINGS1.What is coupling?[NOVEMBER/DECEMBER 2005 /5]The elements which join two shafts are known as couplings. They are used to connectone shaft to another, when the shafts of two independent units, such as electric motor andcentrifugal pump are to be connected.2.Sketch and indicate the salient parts of a flange coupling.[MQP/6]A power of 5 kW at 12 rps is transmitted through a flange coupling. Materials3.for bolt, shaft and key and flange are C60, C40 and CI grade 30 respectively.Design the coupling. [MAY 2005/15(a)]DESIGN OF KNUCKLE JOINTS1. A Knuckle joint is to transmit a force of 140 kN. Allowable stresses intension, shear and compression are 75 N/sq.mm, 65 N/sq.mm and 140N/sq.mm respectively. Design the joint.[NOVEMBER/DECEMBER' 2004.]2. A pin in a knuckle joint is subjected to an axial load of 90 KN. Assume that thethickness of the eye is to be 1.5 times the diameter of the pin. The allowable stressof the material in tension and compression due to bending is 60 Mpa and theallowable stress in shear is 30 Mpa. The allowable bending stress is 20 Mpa.Determine the required pin diameter. (12) [NOVEMBER/DECEMBER 05]UNIT 3DESIGN OF FASTNERS AND WELDED JOINTSSYLLABUSPage 11 of 24

DESIGN OF FASTNERS AND WELDED JOINTS 9Threaded fastners - Design of bolted joints including eccentric loading - Design of welded joints forpressure vessels and structures - theory of bonded joints.THREADED FASTNERSDESIGN OF BOLTED JOINTS1. What do you mean by bolt of uniform strength?[MAY/JUNE 2006/7]A bolt of uniform strength has equal strength at the thread and shank portion.2. How is a bolt designated? Give examples.[NOV/DEC 2006/5]A bolt is designated by a letter M followed by nominal diameter and pitch in mm.For example M24 *2 means the nominal diameter is 24 mm and the pitch is given as 2 mm.3.A steel plate subjected to a force of 3 kN and fixed to a vertical channel by means of four identical boltsis shown inFig. 1. The bolts are made of plain carbon steel 45C8 (Syt = 380 N/mm) and the factor of2safety is 2. Determine the nominal diameter of the bolt.[MAY/JUNE 2006/14b]4. An electric motor weighting 5 kN is to be lifted by eye-bolt, which has been screwed into thebody of the motor. Define the eye-bolt, assuming suitable proportions, if the permissible stresses forthe bolt material are 6u MPa, 30 Mpa and 80 MPa in tension, shear and crushing respectively.[MODEL QUESTION PAPER/13b]5. The cylinder head of a steam engine with 250 mm bore is fastened by eight stud bolts made of 30C8steel. Maximum pressure inside the cylinder is 1 MPa. Determine the bolt size and approximatetightening torque. Take 20% overload. Assumea= 300 MPa for bolt material.[NOV/DEC 2006/13a]y6. A steam engine cylinder has an effective diameter of 350 mm and the maximum steam pressure actingon the cylinder cover is 1.25 N/mm. Calculate the number and the size of studs required to fix the2cylinder cover. Assume the permissible stress in the studs to be 70 N/mm.[MAY/JUNE 2007/13a]2DESIGN OF WELDED JOINTS7. How is welding classified?[NOVEMBER/DECEMBER 2005/7]Page 12 of 24

(a) Forge welding (b) Electric resistance welding (c) Fusion welding.8. Under what circumstances, welded joints are employed?[APRIL/MAY 2005/6]9. What is throat thickness of a fillet weld?[MAY/JUNE 2007/5]10. When will the edge preparation need?[NOV/DEC 2006/6]For plates of thickness less than 6mm, the ends of the overlapping plates can be directly welded atthe edges called edge weld. If the two plates to be welded have more than 6mm thickness, the edgepreparation should be carried out.11.A plate 100 mm wide and 12.5 mm thick is to be welded to another plate by means of two parallelfillet welds. The plates are subjected to a load of 50 kN. Find the length of the weld so that themaximum stress does not exceed 56 N/mm. (Do the calculations under static loading).2[NOVEMBER/DECEMBER 2005/14b]12. A spherical pressure vessel, with a 500 mm inner diameter, is weldedfrom steel plates. The welded joints are sufficiently strong and do notweaken the vessel. The plates are made from cold drawn steel 20C8 (S=TU440 N/mmand St = 242 N/mm). The vessel is subjected to internal22ypressure which varies from zero to 6 N/m!Il. The expected reliability is250% and the factor of safety is 3.5. The vessel is expected to withstandinfinite number of stress cycles. Calculate the thickness of the plates.[MAY/JUNE 2006/13a]13.A welded connection, as shownFig.2is subjected to an eccentric force of 7.5 kN. Determinethe size of welds if the permissible shear stress for the weld is 100 N/mm2. Assume staticconditions.[MAY/JUNE 2006/14a]14. Determine the size of the weld for a bar as infigure 3, when it is loaded in the following manner:(i) Subjected to an axial load of 75 kNPage 13 of 24

(ii) Subjected to a bending moment of 500 N-mm allowable stress in the weld is 900 N/mm2(iii)Determine stress in the weld when it is subjected to a bending Moment of 500 N-mm if the sameBending Moment is produced by a load 0: 2000 N at the end.[ APRIL/MAY 2005/13b]15. A circular rod 45 mm diameter and 210 mm long is welded to a steel plate with axis of therod perpendicular to the plate. The rod is subjected to a load of 10 kN at the free end, thedirection of the load being perpendicular to the axis of the rod. The material of the plate & therod are Mild Steel. Determine the size of the weld to withstand the loading. [MODEL QUESTIONPAPER/13a]16. A circular shaft, 60 mm in diameter is welded to a support by means of a fillet weld as shown in Fig.Determine the size of weld, if the permissible shear stress in the weld is limited to 85 MPa.[NOV/DEC2006/13b]17. A welded connection shown in fig. 1 is subjected to an eccentric force of 7.5 kN. Determine the size ofwelds if the permissible shear stress for the weld is 100 N/mm2. Assume static conditions.[MAY/JUNE 2007/13b]Page 14 of 24

18. An eccentrically loaded plate is welded to a frame as shown inFig.4.Designthe welded joint if the tensile stress in the plate should not exceed 100 N/mm2and that inweld 80 N/mm.[NOVEMBER/DECEMBER' 2004/15b]2THEORY OF BONDED JOINTSRIVETS19.By what material, the rivets are made?[NOVEMBER/DECEMBER 2005/6]a. Mild steelb. Wrought ironc. Copperd. Aluminium20.What type of fit the diameter of rivet hole and rivet will have?[APRIL/MAY 2005/7]21.Sketch any four types of rivet heads, as recommended by B.I.S.[NOVEMBER/DECEMBER'2004/6]22. What is the limitation of the single-strap butt joint?[MAY/JUNE 2007/6]UNIT IV DESIGN OF ENERGY STORING ELEMENTSSYLLABUSDESIGN OF ENERGY STORING ELEMENTS 8Design of various types ofsprings, optimization ofhelical springs- rubber springs --Design offlywheelsconsidering stresses in rims and arms, for engines and punchingmachines.Page 15 of 24DESIGN OF SPRINGSPART A1. Give some of the materials used for springs.[NOVEMBER/DECEMBER 2008/7]2. State any two functions of springs.[NOVEMBER/DECEMBER 2006/7]3. Define the term spring rate.[NOVEMBER/DECEMBER 2005/8]Spring rate is nothing but the stiffness of spring. It is defined as the ratio of load todeflection. Mathematically, stiffness K = W/y , where W = Load,y= deflection.4. What are the applications of concentric spring?[APRIL/MAY 2010/7]5. When two concentric springs of stiffness 100 N/mm and 50 N/mm respectively aresubjected to an axial load of 750 N, what will be the deflection of each spring?[NOVEMBER/DECEMBER 2007/7]6. Two springs of stiffness K1 and K2 arc connected in series. What is the stiffness ofconnection?[ APRIL/MAY 2010/8]7. What are the different styles of end for helical compression spring?[NOVEMBER/DECEMBER 2009/7]8. Why Wahl's factor is to be considered in the design of helical compression springs?[NOVEMBER/DECEMBER' 2004/8]PART B9. A helical compression spring of the exhaust valve mechanism is initially compressedwith a pre-load of 375 N. When the spring is further compression and the valve is fullyopened, the torsional shear stress in the spring wire should not exceed 750 N/mm. Due2to Space limitations, the outer diameter of the spring is not-exceed 42 mm. The-springis to be designed for minimum weight. Calculate the wire diameter and the mean coildiameter of the spring. [MODEL QUESTION PAPER/15a]10. A helical compression spring is used to absorb the shock. The initial compression ofthe spring is 30 mm and it is further compressed by 50 mm while absorbing the shock.The spring is to absorb 250 J of energy during the process. The spring index can be takenas 6. The spring is made of patented arid cold drawn steel wire with ultimate strength of1500 N/mmand modulus of rigidity of 81370 N/mm. The permissible shear stress for22the spring wire should be taken as 30% of the ultimate tensile strength. Design the springPage 16 of 24and calculate:(i) Wire diameter(ii) Mean coil diameter(iii) Number of active turns(iv) Free length; and(v) Pitch of the turns.[NOVEMBER/DECEMBER 2009/14a]11. Design a spring for spring loaded safety valve for the following condition :Operating pressure = 1 MPaDiameter of the valve seat = 110 mmDesign shear stress for the spring = 360 MPaG = shear modulus = 82 GPaThe spring is to be kept in the casing of 130 mm inner diameter and 400 mm long.The spring should be at maximum lift of 6 mm when the pressure is 1.08 MPa.(16)[APRIL/MAY 2008/14a]12. Design a closed coil helical spring for a boiler safety valve which is required to blowoff steam at the pressure of 1.5 N/mm. The diameter of the valve is 50 mm. The initial2compression of the spring is 40 mm and the lift is limited to 20 mm.[APRIL/MAY2007/14b]13. A helical valve spring is to be designed for an operating load range of 90 N to 135 N.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/mmfor the material and modulus of rigidity of 0.8 X210N/mm. Determine the dimensions of the spring. Sketch the spring with dimensions52indicated.[NOVEMBER/DECEMBER 2006/14a]Concentric spring14. A concentric spring is used as a valve spring in a heavy duty diesel engine. It consistsof two helical compression springs having the same free length and same solid length.The composite spring is subjected to a maximum force of 6000 N und the correspondingdeflection in 50 mm. The maximum torsional shear stress induced in each spring is 800N/mm. The spring index of each spring is 6. Assume same materials for two springs and2the modulus of rigidity of spring materials is 81370 N/m. The diametral clearance2between the coils is equal to the difference between their wire diameters. Calculate :(i) The axial force transmitted by each spring,(ii) Wire and mean coil diameters of each spring,(iii) Number of active coils in each spring.[APRIL/MAY 2010/14a]Page 17 of 24FlywheelPART A1. Define coefficient of fluctuation of energy.[NOVEMBER/DECEMBER 2009/10][NOVEMBER/DECEMBER 2007/10]2. Define coefficient of fluctuation of speed and energy.[NOVEMBER/DECEMBER2008/10]3. What is the purpose of flywheel that is used in an IC engine?[APRIL/MAY 2008/10]4. What type of stresses are produced in a disc flywheel?[APRIL/MAY 2007/9]PART B5. A multi cylinder engine is to run at a constant load at a speed of 600 rpm. On drawing thecrank effort diagram to scale of 1 mm = 250 N-m and 1 mm = 3, the areas in square mmabove and below the mean torque line were measured and found to be in order +160, -172, +168, -191, +197 and -162. The speed is to be kept within 1% of the mean speed ofthe engine. Determine the moment of inertia of the flywheel.[NOVEMBER/DECEMBER 2009/15b]6. A single cylinder double acting steam engine delivers 187.5 kW at 100 rpm. Themaximum fluctuation of energy per revolution is 15%. The speed variation is limited to1% either way from the mean. The mean diameter of the rim is 2.4 m. Design a cast ironflywheel for the engine.[NOVEMBER/DECEMBER 2008/15b]7. A single cylinder double acting steam engine delivers 185 kW at 100 r.p.m. Themaximum fluctuation of energy per revolution is 15 percent of the energy developed perrevolution. The speed variation is limited to 1 percent either way from the mean. Themean diameter of the rim is 2.4 m. Design the suitable flywheel.[NOVEMBER/DECEMBER 2007/15b]8. A multi cylinder engine is to run at a constant load at a speed of 500 rpm on drawing thecrank effort diagram to seeks of 1 cm = 2500 Nm and 1 cm = 600, the area above andbelow the mean torque line were measured and found to be in order +1.60, -1.72, +1.68, -1.91, +1.97 and -1.62. If the speed is to be kept with in limits of +- 1% of the mean speed,design the suitable type of flywheel.[NOVEMBER/DECEMBER 2006/15b]9. A punching machine makes 25 working strokes per minute and is capable of punching 25Page 18 of 24mm diameter holes in 18 mm thick steel plates having ultimate shear strength of 300MPa. The punching operation takes place during l/l0th of a revolution of the crank shaft.Estimate the power needed for the driving motor, assuming mechanical efficiency of95%. Determine suitable dimensions for the rim cross-section of the flywheel, which is torevolve at 9 times the speed of the crank shaft. The permissible coefficient of fluctuationof speed is 0.1. The diameter of the flywheel must not exceed 1.4 m owing to spacerestrictions. Check for the centrifugal stress induced in the rim.[APRIL/MAY 2007/15b]10. A punching press pierces 30 holes per minute in a plate using 12 kN-m of energy perhole during each revolution. Each piercing takes 35% of the time needed to make onerevolution. The punch receives power through a gear reduction unit which in turn is fedby a motor driven belt pulley 750 mm diameter and turning at 240 rpm. Find the power ofthe electric motor if overall efficiency of the transmission unit is 80%. Design a cast ironflywheel to be used with the punching machine for a coefficient of fluctuation of speed is0.05, if the space considerations limits the maximum diameter to 1.3 m.Allowable shear stress in the shaft mateial = 48 MPaAllowable tensile stress for cast iron = 5 MPaDensity of cast iron = 7200 Kg/m. (16)[APRIL/MAY 2008/15b]3Belleville spring15. A Belleville spring is made of silicon steel. The spring is compresses completely flatwhen it is subjected to axial force of 4500 N. The corresponding maximum stress is1375 x 106 N/m. Assume d/d= 1.75 and h/t = 1.5. Calculate :201(i) Thickness of washer(ii) Free height of washer minus thickness(h)(iii) Outer diameter of washer and(iv) Inner diameter of washer.[APRIL/MAY 2010/14b]Page 19 of 24

Leaf Springs16. Why leaf springs are made in layers instead of a single plate?[APRIL/MAY 2005/9]17. What is nipping in Leaf Springs? Discuss its role in spring design.[NOVEMBER/DECEMBER' 2004/9]In general the differential curvature between the master leaf and the next leaves isprovided in a laminated spring, where, radius of curvature being more for the masterleaf. This construction reduces the stress in the master leaf as compared to the otherleaves of the spring in a laminated spring. This type of constructional feature is termedas nipping.PART B18. A locomotive spring has an overall length of 1.1 m and sustained a load of 75kN at its center. The spring has 3 full-length leaves and 15 graduated leaveswith a central band of 100 mm wide. All leaves are to be stressed to 420 N/mm.2When fully loaded the ratio of the spring depth to width is to be approximately 2.Take E = 2.1 x 10N/mm.52(i) Determine width and thickness of leaves.(ii) Determine the initial space that should be provided between the fulllength and graduated leaves before the band load is applied.(iii) What load is exerted on the band after the spring is assembled?[NOVEMBER/DECEMBER 2005/11]19. A direct reading tension spring balance consists of a helical tension spring, which isattached to a rigid support at one end and carries masses at the other free end. The pointerattached to the free end moves on a scale and indicates the mass. The length of the scaleis 100 mm, which is divided into 50 equal divisions. Each division on the scale indicates0.5 kg. The maximum capacity of the spring balance is 25 kg. The spring index is 6. ThePage 20 of 24spring is made of an eil-hardened and tempered steel wire of SW-grade (G = 81 370N/mm). The permissible shear stress in the spring wire should be 50% of the ultimate2tensile strength. Design the spring and give its specifications.[MAY/JUNE 2006/15a]20. A semi-elliptic leaf spring consists of two extra full-length leaves and eight graduatedlength leaves, including the master leaf. The centre-to-centre distar..ce between the twoeyes of the spring is 1 m. The maximum force acting on the spring is 10 kN and the widthof each leaf is 50 mm. The spring is initially pre-loaded in such a way that when the loadis maximum, the stresses induced in all the leaves are equal to 350 N/mm. The modulus2of elasticity of the leaf material is 207 kN/mm. Determine (i) the thickness of leaves and2(ii) the deflection of the spring at maximum load.[MAY/JUNE 2006/15b]21. A locomotive spring has an overall length of 1.5 m and sustains a loadof 85 kN at its center. The spring has 3 full-length leaves and 15graduated leaves with a central band of 120 mm wide. All the leaves arestressed to 430 N/mmwhen fully loaded. The ratio of spring depth to2width is 3. Take = 2.1X10N/mm52(i) Find the width and thickness of leaves. (6)(ii) Find the initial space that should be provided between the full-lengthleaves and graduated leaves before the band load is applied. (6)(iii) When load is exerted on the band after the spring is assembled? (4)[APRIL/MAY 2005/11]22. A semi-elliptic leaf spring consists of two extra full-length leaves and sixgraduated length leaves, including the master leaf. Each leaf is 7.5 mm thick and 50mm wide. The center-to-centre distance between the two eyes is 1m. The leaves arepre-stressed in such a way that when the load is maximum, the stresses induced in allthe leaves are equal to 350 N / mm. Determine the maximum force that the spring can2withstand. [MODEL QUESTION PAPER/15b]23. The turning moment diagram of a multi-cylinder engine is drawn with a scale of (lmm = 1) on the abscissa and (1 mm = 250 N-m) on the ordinate. The intercepted areasbetween the torque developed by the engine and the mean resisting torque developed bythe engine and the moan resisting torque of the machine, taken in order from one end are -350, +800, -600, +900, -550, +450 and -650 mm. The engine is running , at a mean speed2of 750 rpm and the coefficient of speed fluctuations is limited to 0.02. A rimmedflywheel made of gray cast iron FG 200 ( = 7100 kg/m) is provided. The spokes, hub3and shaft are assumed to contribute 10% of the required moment of inertia. The rim hasrectangular cross section and the ratio of width to thickness is 1.5. Determine thedimensions of the rim.[APRIL/MAY 2010/15b]Page 21 of 24UNIT V DESIGN OF BEARINGS AND MISCELLANEOUS ELEMENTSSYLLABUSDESIGN OF BEARINGS AND MISCELLANEOUS ELEMENTS 9Sliding contact and rolling contact bearings -- Design of hydrodynamic journal bearings, McKee's Eqn.,Sommerfield Number, Raimondi & Boyd graphs, -- Selection of Rolling,Contact bearings -- Design ofSeals and Gaskets --Design of Connecting Rod.Page 22 of 24DESIGN OF BEARINGSJournal bearing1.Define the following terms of a hydrodynamic bearing (a) Attitude angle(b) Bearing characteristic number.[MAY/JUNE 2006/8]2. What is a 'bearing characteristic number? [MODEL QUESTION PAPER/8]3. Explain the term Dynamic load carrying capacities of rolling contact bearing.[NOVEMBER/DECEMBER' 2004/10]4. What are the effects of clearance on the performance of a bearing?[MAY/JUNE2006/10]5. Following data is given for a 360 hydrodynamic bearing :Journal diameter = 100 mmBearing length =100 mmRadial load = 50 kNJournal speed = 1440 r.p.m.Radial clearance = 0.12 mmViscosity of the lubricant = 16 CpCalculate : (i) minimum film thickness(ii) Coefficient of friction and(iii) Power lost in friction.[MAY/JUNE 2006/12a]6. Design a journal bearing for a centrifugal pump to the following specificationsDiameter of the journal =75 mmSpeed of the journal =1140 mmLoad on each journal =11500 N.[NOVEMBER/DECEMBER' 2004/14a]Rolling bearing7. Select a deep groove ball bearing for a radial load of 4000 N and an axial loadof 5000 N, operating at speed of 1600 rpm for an average life of 5 years at 10 hoursper day. Assume uniform and steady load. [MODEL QUESTION PAPER/14a]DESIGN OF FLYWHEELS8. What is the function of a flywheel?[NOVEMBER/DECEMBER 2005/10]Page 23 of 24Function of a flywheel. : A flywheel used in machine serves as a reservoir which storesenergy during the period when the supply of energy is more than the requirement andreleases it during the period when the requirement of energy is more than the supply.9. Define 'coefficient of fluctuation of speed' in a flywheel. [MODEL QUESTIONPAPER/10]10.What type of stresses are produced in a disc flywheel?[MAY/JUNE 2007/9]11.A rimmed flywheel made of grey cast iron (mass density = 7100 kglm) is used on a3punching press running at a mean speed of 200 r.p.m. The punching operationconsists of one quarter revolution during which the flywheel is required to supply3000 N.m of energy. The coefficient of speed fluctuations is limited to 0.2. The rim,which contributes 90% of the required moment of inertia, has a mean radius of 0.5m due to space limitations. The cross-section of the rim is square. Determine itsdimensions.[MAY/JUNE 2006/12b]Page 24 of 24