CHHATTISGARII SWAMI VIVEKANAND TECHNICALUNIVERSITY, BHILAI (C G)Semester: V th Branch: Itlechanical Engg,Subfect Machine Design - |

Note: 1) De.sign data book by PSG and ISI dala sieefs are allowed in the examination.2) The duntion of the paper is 1(four) hours.

UNIT- I

General Gonsiderations SSelection of Materials, Design Stress, Factor of Safety, Stress concentration factor in tension, bending and torsion,theories of failures.Notch sensitivity, design stress for variable and repeated loads, fatigue stress concentration factor, endurancediagrams.

Ghain DrivesChain drives, roller chains, geometric relationships, dimensions of chain components polygonal effect, power ratingof roller chains.

UNIT- II

Basic Elements DesignTypes of key and design, design of socket-spigot cotter joint, sleeve and cotter joint, gib and Cotter joint, design ofKnuckle joint, design of splines.

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Threaded fastenerc:Geometry of thread forms, terminology of screw threads and thread standards, specifications of steel bolts, initialtension, relation between bolt tension and torque, design of statically loaded tension joints, design of bolted jointsdue to eccentric loading.

Power $crewsPoper screws, Force analysis-square and trapezoidal threads, Collar friction, Stresses in screw, coefficient offriction, efficiency of thread.

UNIT - IV

Riveted JointsTypes of rivet heads, types of riveted joints, failure of riveted joint, strength of rivet joint, efficiency of riveted joint,design of riveted joint for boiler.

Welded joint .rr ?- {t Q,Lrnt-''t:. ''Types of welded joints, stresses in butt and fillet welds, strength of welded joints, location and dimension of welddesign, eccentrically loaded joint, welded joint subjected to bending moment, design procedure, fillet welds undervarying loads, stress relieving techniques.

UNIT-V

Shaft and AxlesTransmission shaft, Design against static load, Design for strength, rigidity and stiffness, design under continuousloading for fatigue"

GouplingsTypes of couplings, design of flange and flexible couplings, compression coupling, muff coupling.

--E7

Class test 2 Machine Design 1

sth semester, Mechanicat Engineering 26.',io.09

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$ol'le any two parts of the following. Assume suitable data wherever necessary:: Qu.1. Determine the throat and leg dimensions for the welds of an eccentrically loaded bracket welded to the support as shown in

Figure. The permissible shear stress for the weld material is 55 lt/mm2.g,Qu.2. Design a cotter joint to support an axial load of Za fglfne mglerial for;gll the components of the joint is steel with theallowable stresses in tension, compression and shear as 50 N/ffi2, 60 l,ilmm2 anffss N/mm2. g.Qu. 3. Determine the kgy dimensions for the following conditions. Ultimate shearing stre$s for the key material is 356 Ulmm2 wittrfactor of safety 5. Take rs = 0.4 oc.h. Shaft diameter-O.09m, shearing resistance of the material of shaft and key are same.i. Shaft dia-1 00mm rotating at 1 00 rpm transmits 224 kW. Power is taken through a gear with hub length 200mm.

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* specify whelher the following stotemenl is conecl or not with reosons in brief.

i. Slress is o veclor quontity since it hos mognitude ond direction only.2' ln bolh the conditions i.e. Plone srre" "ni Plone slroin, tne stresiei'in third direction ore zero.3' ln cose of elemenl loqded in pure sr'eorll.,e mox. principol stress will be twice of mox. sheor slress.4' Design stress is olwoys token os ultimote strenglh, whether moleriol is duclile or brillle.5 Foilure in brittle moteriol under prr. t"riion wiil occur i"

" prr"" p.roilel lo the opplied lood.6. Von - Mises stress.is some os yield stress.

r' v l./rvr re vururter ru rrre opplleo lood.7 ' Slress concentrotion foclor o'epenoion geomelry of lhe element only ond nol on the type of moleriol.B. Enduronce limil ond enduronce strengtn";r. some.9' Enduronce modificotion size foctor ioli iln .or. of elemenl size wiih diometer z.5mm ond ress.,|0.

stiffer the moterior more itwiil oefreci rr Jr4e wrrrr ururlrerer /.Jmm ond I

I 1. Toughness ond hordness qre simitor;oteriol properties.i 2' Von - Mises.criterion is more .onr.ruoriu" ihen Tresco,s criterion.Solve^lhe following:13. Derive the formulolion of Ssy = 0.5 Syp for Moximum Sheor Skess Theoryl4' Drow the Mohr's stress chcles tor oriiue)to2(+ve)>o3(-ver r"Jt"i

"r(+ve)>o2(+ve|>o3(zero).l5' specify strengih ond weoknesrrr oiniurinrm oroy os engineering mqterior.vl6' Draw the lood diogrom ond sheor force diogrom tor tre t6ttowi;t"#ffiiloment diogrom of o simpry supporred beom. (5)

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CSVTU Code:MEo9511B.Tech.( Fifth Semester) Bxamination, April - May 2o1o

Subject: Machine Design-IBranch: Mechanical Engineering

Time: Four hours Max Marks: 80

Min. Pass Marks: 28

Note: All questions are compulsory. Assume suitable data wherever necessary with justification.

Use of PSG data book and data sheets is allowed, Drawings to the scale are to be prepared on

separate drawing sheet to be attached with answer sheet.

Qu. L. Solve any one part of the following:(a) Find the safety factors for each of the following stress*states (MPa) under plane stress

conditions for ductile material with yield strength of 250 MPa and ultimate strength intension and compression as 400 MPa using (i) Principal Stress theory and (ii) Maximum

ShearStresstheory.DrawtheMohr'scircleofstressforboththecases.

(16)

a" oa

b" ox _ -220MPa ;

_ 160 MPa_ -70MPa

Txy _ 60 MPa c.\try'.

Txy - 180 MPa c.c.\ry.

oy

oy

(b) A stepped shaft, with the reduction ratio of 1:2 is to have a fitlet radius of l}Y" of the

smaller diameter. The material of the shaft has noteh sensitivity factor of 0.925, a shearU

stress of 160MPa at yietd and a shear stress of 120MPa at endurance limit. Determine the

diameter of the shaft at the minimum cross section to sustain a twisting moment if itfluchrates}etween 500 Nm to - 800 Nm. Assume infinite life for the element.

Qu. 2. Solve any one part of the following:(a) Design a cotter joint to support an axial load of 30 kN. The material for all thecomponents of the joint is steel with the allowable stresses in tension, compression and shear

as 50 N/m*t, 60 N/mm2 and 35 N/mm2. While designing the sections draw the sketches ofthe sections. Draw the designed joint (assembled) to the scale.

(b) Design a knuckle joint which connects two mild steel rods to transmit an axial load of150 kN. Assume the workins stresses for both the pin and rod material as 80 N/mm2 intension, 68 N/mm2 in shear and 160 N/mm2 in crushing. Assume that the rods to be

connected are not very long. While designing the sections draw the sketches of the sections.

Draw the designed joint (assembled) to the scale.

Qu.3. Solve any one part of the following: (16)

(a) The force required to open or close a submerged sliding water gate is estimated at 27 kN.

It is required to design a single threaded steel screw such that one rnan exerting a pull of360N at the periphery of a hand wheel 1.0m in diameter, attached directly to the screw

can operate the gate. The greatest unsupported length of the screw is found to be 1.5m.

Coefficient of friction for screw and collar is 0.15. The crushing strength of the material

is 210 MN/m2, the maximum working tensile or compressive stress is 70 MN/m2.

AssumeE=210GN/m2.

(16)

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(b) A bolted assembly is subjected to an external force, which varies from 0 to 10 klr[. The

combined stiffness of the parts, held together by the bolt is three times the stiffness ofthe bolt. The.bolt is initially so tightened that at 50oA overload condition, the parts held

together by the bolt are just about to separate. The bolt is machined from plain carbon

steel 50C4 ( Sut = 660 N/mm2 and Syt = 460 N/mm2). The fatigue stress concentration

factor is 2.5 and the expected reliability is 95o/o. The factor of safety is 2. Determine

the size of the bolt with coarse threads.

Qu.4. Solve any one(a) Calculate the

Fig.4(a). The

part of the following: (16)size of the weld required for an ecceltrically loaded weld as shown in

allowable stress in the weld is 75 N/mm2.

(b) Find the diameter of the rivet in arrangement o-f the joint as shown in Fig.4(b). Maximumshear stress in the rivet is limited to 65 N/mm'. The maximum load carried by the joint is108 kN. Assume that all the rivets are of the same size.

Qu.5. Solve any one part of the following: (16)

_(a) A line shaft supporting two pulleys A and B, Fig.5(a) is receiving the power by means ofa vertical belt on pulley A, and is transmitted to pulley B carrying a horizontal belt. The

, ratio of belt tensions is 3:1 and the maximum tension in either belt is limited to 2.7 kN.

-a/*/ The shaft is made of plain carbon steel 40C8 (Sut = 650 N/mm2 and Syt = 380 N/mm2).

'/./V ^ The pulleys are keyed to the shaft. Determine the shaft diameter according to the ASME

94 ) code if kr = 1.5 and kt = 1.0. Check the diameter for the torsional rigidity if the

permissible angle of twist between two pulleys is 0.5o and the modulus of rigidity is

79300 N/mm2.(b) A transmission shaft, supporting two pulleys A and B and mounted between tra'o bearings

C1 and C2 is shown in Fig.5(b). Power is transmitted from pulley A to B. The shaft is

made of plain carbon steel 45C8 (Sut = 600 N/mm2 and Syt = 380 N/mm'). Th. pulleys

are keyed to the shaft. Determine the shaft diameter according to the ASME code ifkn = 1.5 and kt = 1.0. Check the diameter for the torsional rigidity if the permissible

angle of twist between two pulleys is 0.5o and the modulus of rigidity is 79300 N/mm2.

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CSVT'U Course Code:MEo9511B. Tech.(Fifth Semester) Examination, Nov. - Dec. 2oo9

Subject: Machine Design-I

Branch: Mechanical Engineering

TiEme: F'our hours

I{ote: All questions are compulsory, Assume suitable datajustificatian. tlse of PSG data book and ISI data sheets arescale are to be prepared on separate sheet.

2z1-z41r?m. The service cqnditions involve moderate shocks.^t9

- q^- 225-245 r?m. 'I'he Servrce cqndltrons lnvolve moderate snov fuV fil Select a proper roller chain and give a list of its dimensions.

v llll P:'i^",yr*^'::'*::':1"-*:::*r of driving and driven r(ii) Determine the pitch circle diameters of driving and driven sprockets.(iii) Determine the number of chain links.(iv) Specifir the correct centre distance between the axes of sprockets.

Qu.2. Solve any <rne part of the following:

Max Marks I80Min. Fass Marks : 28

wherever necessary withallowed. Drawings to the

Qu.x. S olve arly on e paitof-th e-follo-wing t*ffiry=*.'===-'-'''

(a) The cantilevered shaft, Fig.t, is loaded only by the r8.z kN force. Ascertain thefactor of safety at the hatched crosd-section if the shaft is(i) Ductile with a yield strength of 35o MPa,iii) grittt" *i rti.tirirl *a-"J-p*Jri* ultimate strengths of 3oo and 75o MPa.

Mrlt is required to design a chain drive to connect a 15 kW, rooo qpm petrol%engine to a conveyor. The driving sprocket is mounted on engine shaft. The driven

v)ll sprocket is mounted on conveyor shaft. The conveyor shaft should run between

(a) Design and d.raw the assembled view with fina} dimensions of a cotter joint tosupport an axial load of z8 kN. The material for all the components of the joint issteel with the allowable stresses in tension, compression and shear as 50 N/mme,6o N/mmzand 35 N/mmz.

(b) Design and draw a coupling of flange type for connecting the motor andcentrifugal pump shafts. The details of the duty required from the coupling are:power to be transmitted 18 kW, speed in rev/min 1ooo" Find the diameter of themotor and pump shaft. The allowable stress in shear and crushing is limited to5o N/mm2 and roo N/mma and the angle of twist is not to exceed o.i5 degreesin a length of zo diameters. The allowable shear stress in the coupling bolts isBo N/mm2. Assume the torsional mqment to be transmitted is zo% more than themean torsional moment. The material for the shaft, key and flange is same.

(r6)

(16)Qu.g" Solve any one part of the following:

(a) In the design of a new size reciprocating air compressor, it is proposed that eightbolts be used to fasten the head to the cylinder" The cylinder bore diameter is 75mm, and the maximum working pressure will be g.S N/mms" Desigr the boltsfor a factor of safety of 3 under the following conditions:

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(i) A compressible gasket seal will be used between the head and the cylinder. Thegasket is made from a fibre'sheet, and preliminary calculations indicate that aninitial compression load of about 6+ kN is required on the gasket for a leak proofseai.(ii) An o-ring seal is used with metal to metal contact between the head and thecylinder, and a torque wrench is used to screw up the nut to give the desired initialtension load.The stresses given for the bolt material are ! oyp, = {/a.o N/mmz, oe = 22o.oN/mm2, ou = 55o.o Ny'mma,. The material is machine finished. Stressconcentration factor maybe taken as 2.o.

(i) The dimensions of screw;(ii) The length of nut;{iii) The size of balls.

Qu.4. Solve anytw'o part of the following: (8,8)

(a) A 50-kN load is transferred from a welded fitting into a 200-mm steel channel as illustratedin figure, Fig.4(a). Estimate the maximum stress in the weld.

(b) Determine the throat and leg dimensions for the welds of an eccentrically loaded bracketwelded to the support as shown in figure, x.ig. a(b). The permissible shear stress for the weldmaterial is 55 N/mm2 and the load is static.

G) A boiler joint is to be designed for a steam pressure of z.5N/mm2. The inside' diameter of the largest course of the drum is r.35 m. The complete joint is shown infigure, Fig.4(g). The allowable stresses are ot = 78.o N/mm2, t = 62.5N/mm2,oc = 135.O N/mmz

Q.5. Solve any one part of the following:

(a) The arrangement for a transmission shaft is shown in figure, Fig.S, r8.75lau is to betransmitted through the shaft at r5o rev/mm. The gear tooth reaction actsvertically upward as shown. The flywheel 'F'delivers the power vertieally downwardthrough a belt, the tension on the tight side Fr, being 2.5 times the tension on theslack side, Fz. The gear weighs 9oo N, the flywheel 27oo N and both are keyed tothe shaft. The shaft is made of o.4o per cent carbon steel that has an ultimatetensile strength of 4go MPa and an elastic limit of z8o MPa. l,oads may beconsidered suddenly applied, but with minor shocks only. The weight of the,shaft is

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ft),It is required to design a fly-press, €rs shown in figure, Fig.g, capable of punchingr r./ i6omm diameter circles from a 2mm thick mild steel sheet. The ultimate shear\-4./

strength of sheet metal is 4oo N/mm2 and it can be assumed that shearing will be

_Y cornplete when the punch penetrates through half the thiekness of the sheet. The

J -e screw, with square threads, is made of steel SoCS (Sy, = 4eo N/mm'), while the' .- / nut is made ol bronze. The factor of safety is 3. The operator is expected to seat inV i/ front of the fly-press, insert the sheet by his left hand and operate the handle by the

{, right hand. The total working stroke consists of one-quarter revolution, 45o in^eu front of the press and 45" behind the press. During the return stroke, the punch is.Y

raised by 7 mm to provide clearance to insert the sheet. The forward or workingstroke is complete in z sec. The balls are made of cast iron, with a mass density of7z8o kglms,andthe radius R' is 5So mm. Neglecting collar friction, determine:

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assumed to be negligible in comparison to other loads. Determine the diameter ofthe shaft.

(or)(h\A uniform solid shaft ABCDE, Fig.s&), is supported in bearings at A and D, and

,igtates at 9oo rev/min (rpm). So kW are delivered to the shaft through the 56o"mm diameter belt pulley at C. 3o kW are extracted via the z8o mm diameterpulley at B, and zo kW at the z1o mm diameter pulley at E. At each pulley, the twobelt strands are,parallel and the ratio of tensions in them is g:r. Determine theminimum acceptible shaft diameter if the design stress of roo MPa incorporates anallowance for fatigue

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Noverryrkxr-B.Tech,Siffh Semester) Examinaation, Ilecemtrer

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Code;MES8s112S{}8

CSVTTJ

Note;page.book

Subject: Machine Design-IBranctr: Mechanisal Engineering

Time: Four hours Max lVlarksl 80Min. Pass Marks: 28

All questions are compulsory. Corresponding figures are attached in the lastAssume suitable data wherever necessary witlt justifipation; Use of PSG data

ancl data sheets are allowed.

(B,B)

F ig. L. Show the stressQu. 1. Solve any two part of the followiug:(a) Find the most critically stiessed location on the stepped circular bar,

values at these locations. l

(b) A transmission shaft carries a pulley rnidway between the two bearings. The bencling

moment at the pulley varies from 200 N-rn to 600 N-m, as fhe torsional rnoment in thesirafl varies frorn 70 N-m to 200 N-m. Ttre frequencies of variation of bending andtorsional moments are equal to the shaft speed, The shaft is made of steel FeE 400 ( Sut =540 N/mm2 and Syt = 400 N/mm2). The corrected endurance strength of the shaft is 200N/rnp2. Determine the diameter of the shaft using a factor of safety Z.

kW, 1400 rpm electric motorto a centrifugal pump running at 700 rpm. The sprvice conditions involve moderateshocks.

Qu.2. Solve any one part of the following: (16,16)(a) Design a cotter joint to support an axial load of 30 ld.{. The material for all the

components of tire joint is steel.with the allowable stresses in tension, compression andshear as 50 N/mm2, 60 N/mm2 and 30 N/mnn2. Show the individual failure area anddimensions of the design element through neat sketch

I

(b) Design a knuckle joint which connects two rnild steel rods'tl ,r*r-i, an axial load of200 kN. Assume the working stresses for both the pin and rod material as 80 N/mm2 intension, 70 N/mm' in shear and 150 N/mm' in crushing. Absume that the rods to beconnected are not very long. Show the individual failure arpa and dimensions of thedesign element through neat sketch i

Qu.3, Solve any one part of the follorving I

(a) (i) Explain the foice deformation diagram of a bolted joint add develop the expression(Pu),r,u*:P;[(k6' +kr')/kr'], where the symbols have their usual ineanings. (6)(ii)A steel plate subjected to a force of 5 klr{ and fixed tb a dhannel by means of threeidentical bolts,is shown in Fig. 3(a). The loits are made of plain carbon steel 30C8 ( Syt= 400 N/mm2) and the factor of safety is 3. Determine itreinominal diameter of thebolts. ii (10)

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(b) It is required to design a double start screw with,square threaps for the C clamp shownin figure, Fig.3{b). The maximum force exerted by the clamp [[s skN, It is assumed thatthe operator will exert a force of 250 N at the ball handle of t$e hand wheel. The screwis made of plain calbon steel 45C8 ( Syt = 330 N/mm2), while the nut is made of greyo cast iron tr'G200. The dimensions of the collar are shown seRarlately in figure, The factor

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'.of safety is 2.5. Dqtermine the ciirncnsions of the screw anrJ the uut and calculate the '!i\*'

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radiusR,ofthebaittandte. (16) "-|g

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Qu.4. $ol'se arry onb p[rt of the follorving: {l{i"16)(a) A solid iircufa{ shaft, 25mm in cliameter, is welded to a'support by means of a fillet

weld as shown [n fig.nqa1. Determine the leg climension of the weld if the perinissible

shear stress is 95 N/mm'.I.{

(b) The riveted **Lnb.t shown in figure, Fig.aft) is fastened to a beam, arrrl an eccentric

loacl is appliedi fuvets A and C ll.ave 16 mrn diameter and at B and D have 22 rnw.

diameter; Assuming the yield strength of the rivet as 580 N/mm2, detetmine the f'actor

of safety igainqt the shear of the rivets.

i

Qu.S, Solve any one pprt of the following:(a) A uniform rotia rn* ABCDE, fig"S(a) is rypported in bearings at A and l), and

rotates at 900 nev/min (rpm). 50 kW at'e cielivered to the shaft through the 560 mrn

diameter belt pglley at C. 30 kW are extracted via the 280 mm diameter pulley ai fl,

and 20 trW at the 210 mm diameter pulley at E. At each pulley, the tlvo belt strands are

parallel and th,b ratio of tensious in them is 3:1. Detennine the minimrtrn acceptabie

slaft diameter if the clesign stress of 100 MI'a incorporates an allowance for fhtigue.

ii

(b) A ffansmissiori shaft supporting two pulleys A and B md mounted befween two' ' bearings C1 and C2 is slioram in Fig.S(h). I'owcr is t'ansmitted {rom-pulls-; A to B. The

shaft is made cf piain carbon steei"4sc'S ( Suf = 600 N,'mmz aud Syt - 38tt Nlmm2).

The pulleys are ke,ved to the shaft. Detemrine the shaft diameter using the ASME code

if ko=1.5 and.kt=l.$. Also determine the shaft diameier on the basis of torsional

rigidity, if the permissibie-angle of twist befween trvo pulleys is 0.50 and the niodiiius

of rigidity is 79300 N/mrn'.

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CSVTU .... Code:MEo75uB.Tech.( F-ifth Sernester) Examination, December z.oaT

' Subject: Machine Design-IBranch: Mechanical llngineering

Time: Four hour NIax Marks:80NIin. Pass Marks: 28

Note: Atl questions are compulsory. Assume suitable data wherever necessary withjustification. Use of PSG data book and data sheets are allowed. Drawings to the scale are to

be prepared on separate drawing sheet to be attached with answer sheet.

Qu. 1. Solve any one part of the following:(a) Find the safety factors for each of the following two-dimensional stress statesunder plane stress conditions for ductile.material with yield strength of 500 MPa via(i) distortion energy theory and via (ii) maximum shear stress theory

A. ox = B0 i '(fy = L7A , Txy = 60 C.w.

b. ctx = -220 , oy = -7A , T^y = l$$c.c.vl.c. oy - -205 i sv _ - 445 i rxy - 35 c.w.

(b) tt is required to design a chain drive with a duplex chain to connect a rF kW,14oo rpm electric motor to a transmission shaft running at 3So rprn. Theoperation involves moderate shock. As a preliminary design the eenter distance can

be assumed as 4o times the pitch of the chain. (t6)

Qu.z. Solve any one part of the following:(a) Design a cotter joint to support an axial load of z8 kN. The material for allthe components of the joint is steel with the allowable stresses in tension,compression and shear as bo N/mm2, 6o N/mmz and 35 N/mmz, Draw thedesigned joint (assembled) to the scale.

(b) Design a knuckle joint which connects two mild steel rods to transmit an

axial load of r5o kN. Assume the working stresses for both the pin and rodmaterial as 8o N/rnm2 in tension, 68 N/mm, in shear and 16o N/mmz incrushing. Assume that the rods to be connected are not very long. Draw theassembled joint to the scale.

Qu.3. Solve any one part of the following(a) A bolted assembly is subjected to an external force, which varies from o to 10

kN. The combined stiffness of the parts, held together by the bolt is threetimes the stiffiress of the bolt. The bolt is initially so tightened" that at 5oo/o

overload. condition, the parts held together by the bolt are just abodt to

separate. The bolt is machined. from plain carbon steel 5oC4 ( S,rt = 66oN/mm, and Syt = 46o N/mmr). Ihe fatigue stress concentration factoris 2.5 and the expected reliability is gSY". The factor of safety is z.Determine the size of the bolt with coarse threads.

( 16)

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(b) Uesillfuhe screw drive of a jack for load capacity of roo N. The lifting height iso.Sm. The basic design of the jaclc is as given in Fig.3. Assume the material forthe screw as Cz5'steel and for nut as phosper bronze. Determine thedifferent dimensions of the screw and check it against the induced stresses.

Assume coefficient of friction for nut and. screw as o,la5.t

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Qu.4. Solve any one part of the following:(a) A roo klrl load is transrnitted from a weld fittihg into a zoo mur steel channel

. as shown in FiS.+(a). Estimate the. maximum stress in the weld. Alldimensions are in mm. (16)

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(b) A Hkcket is to be attached to a wall with the help of six rivets. The differentarrangements in which,the bracket can be attac-hed to the wall with these rivetsare shown in Fig.4ft). The maximum allowable stress in shear is 6o N/mmr.Deternrine the way in which the rivets should be arranged so that the design isecon<imical. fhe bracket is required Io support a load of 90 Id.I with aneccentricity of zoomm. (16)

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Qu.S. Solve any one part of the following:(a) The layout of a two-stage zo kW V-belt speed reduction is shown below. The

first stage consists of a rz5 mm diameter engine-driven input pulleyrotating at 24oo rpm and drivint a 4oo mm diameter pulley mountedon an intermediate shaft. The zoo mm diameter srnall pulley of thesecond stage is also mounted on this intermediate shaft, and drives the 68omm diameter output pulley connected to the load. Tensions obtained frombelt:analyses are indicated on the sketch. The intermediate shaft abcdhas to be designed. Select suitable diameters Dr and Dz for the intermediateshaft given that the duetile material's design stress, oa = Sln, is zg MPa.

(16)

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(b) Determine the machine shaft diameter, running at 6oo rpm and supportedon bearings o.7bm apart. rS kW is supplied to the shaft through a o.45mpulley located o.2bm to the right of the right bearing. The power is

i transmitted from the shaft through a o,2om spur gear located o.25lrr tothe right of the left bearing. The belt drive is at an angle of 6o" above the

horizontal. The pulley weighs 9oo N. The ratio of belt tensions is 3:r. The

gear has ts" pr"rrure angle and meshes with another gear located directlyabove the shaft. The material properties are : Ultirnate strength = 49aMN/rirrnz, Yield point stress = 962 MN/mmz. Assume I(5 = t.5 and

IQ = 1.o. (16)

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TIME : Four hours

NoyB'E (rifth :ffi?i;;l?ffi1il*:fN'

2005

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Max. Msrks : 100

Min. Msrk$ ; 35

codes are allowed. Assume suitable

data wherever necessary. Drawings are to be made in a separate sheet to the scale.

Qu. 1. Solve any two part of the following:----Lr': (i) Compute the factor of safety for Max Normal Stress theory, Maximum Shear Stess theory

and Distortion Energy theory, for the foltowing state of stress. The material has a yield

strength of 600 MPa. Plot the resulb.

a. 01 * 42A MPa, o2 = 420 MPa, $s = 0

b. or = 0 MPa , 62 = -L80 MPa, os = -42A MPa

(ii) Design a cantilever bracket by determining its diameter to support a fully reversed bending

load of 500 N amplitude for 10e cycles with no failure. The cantilever is made of cold drawn

steel C50 having machined surface. The notch sensitivity factor at the fillet can be taken as

0.85. The operating environment is room temperature and the reliability factor is assumed at

9A7o. If the schematic diagram of the element is as shown in Fig.1

i:'

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(iii) A plate of width 1.4 m and length 2.8 m is required to supPort a tensile force in the 2.8 m

direction of 5 MN. Inspection procedures detect through thickness edge cracks iarger than 3

mm. The two Aluminum alloys are being considered for this applicatiory for which the

safety factor must be 1.4 and minimum weight is important Which alloy should be used, iffracture toughness is govemed by the equation, KI = 1.2 o{ fia'

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455

495

{10}

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(10)

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Qu. 2. (a) A uniform solid shaft ABCDE is supporbed in bearings at A and D, and rotates at 800 rev/min

(rpm). 50 kW are delivered to the shaft through the 560 rnm diameter belt pulley at C. 30 kW are

exbacted via the 280 mm diameter puley at B, and 20 kW at the 210 mm diameter pulley at E. At each

pulley, the two belt strands are parallel and the ratio of tensions in them is 3:1. Determine the minimum

nr.c "

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'- ' accePtable shaft diameter if the deeign stress of 100 MPa incorporates an allowance for fatigue,I

(?01

(b) The layout of a two'stage 30 kw V-belt r** ,(:t*tion is shown below. The first stage consisb of a125 mm diameter engine-driven input pulley rotating at2400rev/min and driving u ld** diameterpulley mounted on an inbermediate shaft. The 200 nm diameter small puiley of the second stage o

"rr"mounted on this intermediate shaft, and drives the 630 mm diameter outpuf puiley connected to theload' Tensions obtained from belt analyses are indicated on the skekh. The intermediate shaft abcd hasto be designed' select suitable diameters D1 and D2 for the intermediate shaft given that the cluctilemaberial's clesigr shess ( cr.r = S/n ) is 25 Mpa. (20)

Qu- 3- {a} which lap joint is *rorc *ffectivc, the transverse or

INTERMEDIATE 5I.IAFTPBELIhIF{AFY LAYflJT

the langitutlinntr, ftnd by how much

{2s}

ern thick br**$qet fastsned to a 3 em thick rnfrin plate with Sof the riv*t if the allowable shear stress is 1000 kg/cma. All

{20}

P.To.

.T:L,.f,*

(b) A 6000 kg toad is to be supported by a a" srivets as shown in Fig. 3(b). catculate the sizedimensions are in mm.

,*t 50

Nol to sesl*Slrnensi*ns in nnm

9

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