Dmm-2 Question Bank.docx

ACE Engineering College Ankushapur(V), Ghatkesar(M), R.R.Dist - 501 301

Year/Class: III Yr. MECH-A & B

SUBJECT: DESIGN OF MACHINE MEMBERS-2

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What is bearing? What is viscosity? Explain the types of lubrication? Differentiate between Hydrostatic and Hydrodynamic Lubrication systems? What do you understand about Viscosity? Explain Petroff’s Equation in detail? Explain the dimensionless parameters using Raimondi and Boyd Method? The following data is given for a full hydrodynamic bearing: Journal speed=1440rpm, journal diameter=120mm, bearing length=60mm, radial clearance=0.06mm, radial load=3KN, viscosity of lubricant=40cp Assume that total heat generated due to friction in bearing is carried by the total lubricant flow. Calculate (a) coefficient of friction, (b) minimum oil thickness, (c) flow requirement, (d) temperature rise, (e) power lost in friction 9. A hardened and ground journal, 50mm in diameter, rotates at 1440rpm in a lathe turned bronze bushing which is 50mm long. For hydrodynamic lubrication, the minimum oil film thickness should be five times the sum of surface roughness of the journal and the bearing. The data above machining methods is as follows: Machining Method Surface roughness (cla) Shaft Grinding 0.8 micron Bearing Turning/Boring 1.6 micron The diametral clearance is 0.119mm and viscosity of the lubricant is 18cp. Determine the maximum radial load that the journal can carry and still operate under hydrodynamic conditions? 10. The following data is given for a 3600hydrodynamic bearing: Radial load=30KN, journal diameter=75mm, bearing length=75mm, journal speed=60rps, diametral clearance=0.30mm, inlet temperature=400C, The temperature-viscosity relationship as follows: T(0c) 40 41 42 43 44 45 46 47 48 49 50 Z(cp) 52.5 50 47.5 45 43 41 39 37.5 36 34 33 Assume that the total heat produced in the bearing is carried by the total oil low. The specific gravity and specific heat of the lubricant are 0.86 and 1.76 KJ/Kg0c respectively. Evaluate the power lost in friction and the requirement of oil flow?

ACE Engineering College Ankushapur(V), Ghatkesar(M), R.R.Dist - 501 301

Year/Class: III Yr. MECH-A & B

SUBJECT: DESIGN OF MACHINE MEMBERS-2

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Define static load carrying capacity? Explain about STRIBECK’S EQUATION? Define dynamic load carrying capacity What is equivalent bearing load? What do you understand about load-life relationship? For a single-row, deep-groove ball bearing, C=5590N, C0=2500N. Actual loads on bearing are axial load is 625N, radial load is 1250N. Determine the equivalent load of ball bearing if: (a) Inner race is rotating (b) Outer race is rotating 17. If the designation of a bearing is 6308, give the complete specification from SKF catalogue and determine its life at 20,000N dynamic load. If the bearing rotates at 720rpm. What is the life in hours 18. A ball bearing carries a radial load of 3.5KN and is to be designed for 6,000hours of operation at 1400rpm with a reliability of 98%. What is the dynamic load capacity of the bearing, as selected from manufacture’s catalogue? 19. A single row deep groove ball bearing is used to support the lay shaft of a four speed automobile gear box. It is subjected to the following loads in respective speed ratios: GEAR First gear Second gear Third gear Fourth gear

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AXIAL LOAD(N) 3250 500 50 Nil

RADIAL LOAD(N) 4000 2750 2750 Nil

% TIME ENGAGED 1 3 21 75

The lay shaft gis fixed to the engine shaft and rotates at 1750rpm. The static and dynamic load carrying capacities of the bearings are 11600 and 17600N respectively. The bearing is expected to be in use for 4000hoursof operation. Find out the reliability with which the life could be expected Explain about buckling of connecting rod Explain about the design of cross-section for connecting rod Derive the equation for designing of big and small end bearings of connecting rod Derive the equation for designing of big and small end caps for connecting rod What do you understand about WHIPPING stress The following data is given for a connecting rod: Engine speed=1800rpm Length of connecting rod=350mm Length of stroke=175mm Density of material=7800kg/m3

ACE Engineering College Ankushapur(V), Ghatkesar(M), R.R.Dist - 501 301

Year/Class: III Yr. MECH-A & B

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SUBJECT: DESIGN OF MACHINE MEMBERS-2

Thickness of web or flanges=8mm Calculate the whipping stress in connecting rod Determine the dimensions of cross-section of the connecting rod for a diesel engine with the following data: Cylinder bore=100mm, Length of connecting rod=350mm, Maximum gas pressure=4MPa, factor of safety=6 Determine the dimensions of small and big end bearings of the connecting rod for a diesel engine with the following data: Cylinder bore=100mm, Maximum gas pressure=4MPa, (l/d) ratio for piston pin bearing=2, (l/d) ratio for crank pin bearing=1.3, Allowable bearing pressure for piston pin bearing=12MPa, Allowable bearing pressure for crank pin bearing=7.5MPa Describe how an I-section is designed for a connecting rod What is the advantage of using longer bolts at the big end of connecting rod Design a connecting rod for a petrol engine with the following data: Piston diameter=80mm, weight of reciprocating parts=15N, centre to centre length of rod=250mm, stroke=110mm, RPM=1500 with 50% over drive, compression ratio=7:1, Estimated maximum explosion pressure=2.5MPa, FOS=5 for connecting rod and bolts