Mechanical Engineering Reviewer-Machine Design.pdf

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! .

ALCORCQN ENGINEERING

REViEWdCE~T~

"~:C::Manila:

4th Fir.

A~adeta'

Bfdg. 891 Galicia Sl cor;-esp/ipa Ave. SJrnpalOc Manll~ (Tel. 742-56-00)

.~;, :"~Cebu: 4TH _Fir._{Villacatnpa-Capuras Bldg .• Sanciaj1gcxrSt}~b9\ _CItY_(Tel_If._25+33-84)

.~': • ! " . J ! ' ,

t\lIACHI~E DE~IGN!...! ~.~Y

2 . "

',"

,SHARI

j_ .. ><.- 1-! _""', -;,~, ""' ! DEFINITIONS:

!

_.

i , 1 ;

Shaft - . .is

_.

a

rotating member that is- used to transmit power .

"

.,

where: P

=

power, Hp ~: Torque, T ---".,--.. ~~."-,.

:§;

T

=

FxR=FxD/2 f~:.

R~~re

F

=

jipplied force Shaft R

=

radius

3. stresses in shaft when subjected to pure torsion(Ss)

where:

A For solid shaft: Ss

=

Tc _1ST

T-

1td3 Coun1ter Shaft"

-Dri~'.M~Chlne

1 ; (l~ Driven Machine:2 ; ,:~ -:s'" ! • I

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c. For shori shafts:

From Machineries Handbook

1. Shaft diameter for 0.08 degrees

per

foot of length of shaftdefiection.

C9J0

For English units:

0:::;; 0.29

ff

or D;:; 4.6

~

Where: 0 "" diameter,jn P :::;; horsepower N :: speed, rpm

P "'power, ttl' D:: diameter, in N "'speed,

rpm

T 1tor~ue, in-lb.

A. Shafting SUbjected-to nO'bendingadiott of pulleys except its own We'ight-i " L :: 8. 95 ..

~ ~tJ

') B. 'Shafting subjected to

bar.ding

a~on

of

pulleys, etc: L:::;;

5.2'

frl,

(~)

W h e r e : " ' "

L ::: shaft length, ft ' D,;::: sha1ldiameter, in

Al.CORCONEN(3INEe8INGREVIEW GENTER'

Maniia, 4111 _{Fir. Anacleta Bldg. 89t.Galicia Steer. Espana Ave. SampalpcManila:.(fel. 742-56-00).}

," Cebu: 4~ Fir. Villacampa-Capuras

aI99 .•

\~ancjangco St Cebu City"(fet # 254-33-84)

" ... ,"", ' " ~' j --~' :

i ,:-/ {: .," ,~~,:, _', '_ '_',,:, __ ' : ~

Machir1E~'

Des'igri

Problem$.-

DAY 2

'-1' \~~ ";":,-.- '-'~,! ' j

SMAFi;.S~BJECTED

TP

PURE TORSION,6Nl

Y,~

. ,.,' ....

r.~ (ME:8d. Oct 1998)Wha! pqwsr wouldiasp".indle§5

n:m

hid. iametett,r~smit at 480,',rpm stress allowed for

short

shaft IS 59N/mm2

?'CMS,

%

;~f>

\LW)

~41J\~n(;;

'i!IDL. . '

2." (ME Bd. Apr. 98) Compute the diameter

ot'a

solid shaft tr~i:'lsmitting 75 Hp at 1800

rpm.

TI1.e nature of theJqad and;the tYpe of servi,ce j~ su~ tliat the, a"owable Ss based on pure

tqrsion is

6000 pSi.

. :,"

';~:.'.

,,'

. . r i

3. '(ME Bd. Oct.2fJ~F..jnd the torsional defl~iOPt indegrees •. of a solid steel shaft, 110

mm

OD

x

1.4

m I0l19subjecfto

3.

t

x

106 _{N-mm ton;:tue.}

_The

t9r~ional

_modulus

_{of elasticity is}

80,000 N/mm-mm., • ..

','. ", .• ".'

. '

. ' . '. '

4. {ME Bd. Apr. ~6}Computethe linear, shaft diaroeter to tri:msmit 12 HP at 180 rpm with torsional deflection of ~08 degrees per fo~t length ..

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5. (ME

ad.

Apr. 95) A hollow shaft with outside diameter o{ 14 em ~nd wall thickness of . 0~8 em transmits 200

J<MI

at 400rprn. What must be the angular deflection of the shaft if the

iengthis 5 meters? The material

of

the shaft is C4140 steel .. '.

SHAFT WITH ASSUMED ALLOWABLE STRESS

1. (ME Set

Oct.

95) A short 61 mm diameter shafUransmiis "120 Hp. Compute the linear speedof a pulley 55 em diameter mounted on the shaft.

2. (MEad. Apr, 95) Compute th~ speed of the gear mounted en main shaft with 52.5 mm diameter re~iving power from a drivipg motor with 250 Hp.

: SHAFT SUSJECTEP'TO

TORSIO~ANO

BENDING LOAD

1. A machine shaft is supported on bearings 1 m apart is to transmit 190

I<YV

at 300 rpm while subjected to bending load of SOO kg at the center. If maximum shearing stress is 40

Mpa, determine the shaft diameter.

FROM MACHINERIES HANDBOOK .

1. (ME Bd. Apr. 98) A 16 ft lineshaft has no bending action except its own w!':)ight. What power in

Hp

can ~he shaft deliver at a speed of 200 rpm. Consider that the torsional defiectionwill not exceed 0.081ft length.

SITUATIONAL PROBLEMS

~,. (ME Bd. APRIL:2004) A shaft that has a diameter of 1.125 in has 'an appjiegtorque

of

400 in-lb. A shear pin is used to conn~ the shaft has a ractor of S9fety of 2.5. The S;.::: .

73.9 ksi and Ss :: 0.577 Syt. Determine: , , . / . . ' "

1. Allowable shearing s~ of the shaft. psi . , '. .

A 1230.78 psi\!U14~.r8 psi C. 1530.78 psi D. 1630.78 2. M~:' urn shear force of the shaft, I b s ' . . ' i

. A. 711.11 B: .721.11 C.731,11, D.741.11

3. Shea pin diame~r, in 1 .

f::\

.. : A 0.475 . ,8. 0.375 C. 0.275 ~0.175 4. MaXimum shear force in kg.. .

f:\ .

.

A 302.50

kg

B. 312.5,9 kg

\...SJ322.50

kg D. 332.50 kg .

5; Sh~'n diameter, mm'· ' .

',A.445

i

B.

4.545:

C.

4,645

D. 4.745

"

~.~

,. (ME .. APRIL 2(04) A hollow

~haft

has an. outside diameter of 2in.

Th~

allowable shearing stress of the shaft is 7,000 psi and the applied torque is 700 in-lbs. Find:

1. the shaft insid8?~iameter, in ~ .

, A .1.95 in . B. 1.~3 in . C. 1.91in. ~1.97 in 2. the equMilent solid ~ diameter, In j

A

0.788

\J!)O.798

C.

0.792 D. 0.790

'

. 3. savings in weight if the s9lid shaft is to be

fW

with hollow shaft of the same torsional

I strength. A 76.20%' B. 78.20% C. 81.29% D. 85.30% •

4. the~r of safety if yield stress is 10,430 '.

A. 1.49 B. 1.69 C. 1.79 D. 1.99

5. tan 'al force of the solid shaft, lbs

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ALe RCON ENGINEERING REVIE

4th Fir. Anacleta Bldg. 891 Galicia st. cor. Espana Ave. Sampaloc Manila Tel # 742-56-00

SHAFTING

PROBLEM SeT

#

2

INSTRUCTION: Encircle the letter that corresponds to the correct answer of your choice.

M\JL TIPLE CHOICE: .

CENTER

~/,,, -:/'~'/'

I

""1~~A

shaft is used to transmit 200

~

at 300 rpm by means of a 200 mm diameter sprocket Determine the

" force tangent to the sprocket.

@

/ . " A 60.44 KN S. 60.33 KN C. 60.88 KN O. 63.66 KN

~. Findthe diameter of a steel shaft which wil! be used persia a 110 KW

motor

rotating at 5 rps if torsional

, stress is 90 Mpa. ~

A.

60.20 nim . B 58.30 mm C. 38.30 mm O. 46.20 mm

shaft has an ultima €I stress of 350 Mpa and has a factor of safety of 5. The torque developed by the shaft. is 3 KN-m and the diameter outsidea2eter is 80 mm. Find the inside diameter of the shaft.

A. 83.45 mm B. 76.45 mm C, 69.62 mm D. 66.34 mm

Wh~' the speed of 63.42 mmsha nsmitted 75 'rWI/ if stress is not to exceed 26 Mpa, A 550 rpm B. 600 rpm C. 650 rpm D. 700 rpm '

A st shaft transm~p at 1400 rpm. If allowable stress is 500 psi, find the shaft diameter. A 3.58 in. B. ..84 in. C. 1.65 in. D. 2.54 in. '

shaft of a motor as a length of 20 times its diameter and has a maximum twist of 1 degrees when twisted at 2 KN-m torque. If the moduius of rigidity of the shaft is 80 Gpa, find

the shaft diameter. ~

A

69.23 mm 8. 73.23 mm C. 64.23 mm D. 66.33 mm

7. A hollow shaft developed

a

torque of 5 KN and shaft s ressis 40 Mpa. If outside diameter of srlaft. is 100

mm, determine the shaft inner diameter. ~

.

A

68.43 mm S. 63.28 mm C. 58.38 mm D. 77.64 mm

8. A hollow shaft that has 100 mm outside diameter ana 0 mm inside diameter is lIsed to transmit 100 KW at

60t:],

Determine the shaft stress. .

A

13.73 Mpa 8.16.82 MPa C. 19.86 MPa D. 17.21 Mpa

Wti' , the polar morhent O~H tia of a solid shaft that tlU!::> a torque of 1 .5 KN and a stre, S5 of 25 Mpa?

A 2.46x10·6_m4 _{8 . .}_Q2x10-6m₄ _C,3.46x10-6_m₄ _0.1.24x1O·_6m4

0. A force tangent to 1 foot di er pulley is 5 KN and is mounted on a 2 inches shaft.. Determine the '

E

o . 131 deflection

if

G =: 83 x 106 Kpa .

. ,,/ A. 0.804°/m 8. O.654°/m C. 0.786°/m D. O.938°/m

... ;).1':'..

is the minimum diameter of a steel shaft which will be used to operate a 14 KN.m torque and will not

/ twist more than 3" in a length of 6~. :: 83 X 106 _kPa) _. _.

A. 100.64 mm 8. 96.80 mm C. 118.45 mm D. 120.72 mm .

A solid shaft 5 m long is stressed to pa when twisted through 4". Find the shaft diameter if G =6 83

GJ?a.

~

; / / A

95.46 mm 8. 90.42 mm C. 101.32 mm D. 103.54 mm

... ···/13. Compute the maximum unit shear in a 2 inches dia er steel shafting that transmits 24, 000 in~lb of torque

~

t1

o

rpm. .

.... / ' 'A.

15,279 psi 8. 17,456 psi C. 14,233 psi D. 16,344 psi

//1'4..

.

the ~iameter of line s~aft that transmi~ 150

't<MJ

at 15 rps?

I

/,,/

A.

2.28 In. 8. 3.54 In. C. 1.62 In. D. 2.06 In.

/'15. A In shaft has 50 mm diameter is running at 300 rpm. What is the power that could be deliver by the

shaft, ~ .

/ ' / A. 30.40 hp

\§)

28.60 hp C. 32.50 hp D. 16.42 hp

~6. ' A 2 inches diameter main shaft running at 600 rpm is mounted by a 12 inches diameter pulley and is Ulen , connected to the shaft of driven machine mounted by a 40 inches diameter pulley by means of a belt. The

beit efficiency is 90%. Find the diam~of the short shaft.

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1.5" diameter Sl]haft is used to transmit 44.4 hp. Determine the shaft speed. "A/SOO

rps

8. 8.33rps C. 400

rpm

D. 450

rpm

1 ~y>K3" diameter soli

ft

is desired to replace a hollow shaft having 4" outside diameter. Consider the

/ ' strength to be the same, determin~-inside diameter of hollow shaft.

A. '2.5 in. B. 3.0 in. C..5 in. D. 4.0 in.

1 ~.A~;~motor is used to drive a centrifu ump that discharges 3000 Hlmin at a head of 10m. The pump - efficiency is 68% and running at 550 rpm. Find therfl0nal stress of shaft

if

shaft diameter is 35 mm .

. A. 13.85 MPa B. 11.85 MPa C. 12.85 MPa D. 4.87 Mpa .

~~irCUlar

saw blade has a circular speed of 25 mls nd 500 mm diameter is driven by a belt that has a

~

Ii 7%. Find the required speed of driven shaft

if

speed ratio is 3. .

A. 954.80 rpm B. 2533.56 rpm C. 3542.45 rpm D. 3015.57 rpm

2',1. 0 mm diameter circular saw blade is driven by a 1800 rpm motor with gear speed ratio of 1.8. Find

th~heral speed of the blade.

,~37.43ft1sec B.140.65ft1sec C.132.43ft/sec D.135.21ft1sec

~~/'/A machine shaft is supported on bearings 1 m apart is to transmit 190 IWV at 300 rpm while subjected to / ' bending load of 500 kg at the cente~shearjng stresses 40 Mpa, determine the shaft diameter.

A 100mm B.90mm C.94mm D.98mm

-

.~O

mm diameter shaft is subjecte to a torque f 6 KN.m and bending moment of 2.5 KN. m. Find the

m um bending stress developed.

A. 45.84 MPa B. 60.25 MPa C. 50.28 MPa D. 55.46 Mpa

t has a length of 10 ft. Find the diameter of the shaft that could safely deliver.

A. t18in B.7.55in C.2.34in D. 1,64in

shaft is running at 260 rpm. vynat that this s!:l.aft could safely deliver?..J .