answer key dynamics of machinery
Post on 03-Jun-2018
249 Views
Preview:
TRANSCRIPT
-
8/12/2019 Answer Key Dynamics of Machinery
1/15
ANSWER KEY FOR PART A
1. The inertia force is an imaginary force, hich hen acts !"on a rigi# $o#y, $rings it
an e%!i&i$ri!m "osition. 't is n!merica&&y e%!a& to the acce&erating force in magnit!#
$!t o""ositein #irection.
(athematica&&y, 'nertia force ) Acce&erating force ) m.a
Where m ) (ass of the $o#y, an# a) *inear acce&eration of the centre of gra+ity
the $o#y.
. -A&em$ert/s "rinci"&e states that the res!&tant force acting on a $o#y together
the re+erse# effecti+e force 0or inertia force are in e%!i&i$ri!m.
2. The t!rning moment #iagram 0a&so 3non as cran3 effort #iagram is the gra"hic
re"resentation of the t!rning moment or cran3effort for +ario!s "ositions of the cran
't is "&otte# on 4artesian coor#inates, in hich the t!rning moment is ta3en as t
or#inate an# cran3 ang&e as a$scissa.
5. 't is #efine# as the ratioof the ma6im!m f&!ct!ation of energy to the or3 #one "
cyc&e.
7. The "rocess of "ro+i#ing the secon# mass in or#er to co!nteract the effect of the
centrif!ga& force of the first mass is ca&&e# $a&ancing of rotating masses.
8. 'f rotating "arts are not "ro"er&y $a&ance#, the #ynamic forces are set !". The
forces not on&y increase the &oa#s on $earings an# stresses in the +ario!s mem$e
$!t a&so "ro#!ce !n"&easant an# e+en #angero!s +i$rations. 'n or#er to minimi
"ress!re on the main $earings hen an engine is r!nning, the rotating "arts sho!
$e $a&ance#.
:. The ma6im!m magnit!#e of the !n$a&ance# force a&ong the "er"en#ic!&ar to the &i
of stro3e is 3non as hammer $&o.
;. The res!&tant !n$a&ance# force #!e to the to cy&in#ers, a&ong the &ine of stro3e,
3non as tracti+e force.
-
8/12/2019 Answer Key Dynamics of Machinery
2/15
1=. Free or nat!ra& +i$rations .When no e6terna& force acts on the $o#y, after gi+ing it
initia& #is"&acement, then the $o#y is sai# to $e !n#er free or nat!ra& +i$rations.
Force# +i$rations.When the $o#y +i$rates !n#er the inf&!ence of e6terna& force, th
the $o#y is sai# to $e !n#erforce# +i$rations
11. The s"ee# at hich the shaft r!ns so that the a##itiona& #ef&ection of the shaft fro
the a6is of rotation $ecomes infinite is 3non as critica& or hir&ing s"ee#.
1. The ratio of the act!a& #am"ing coefficient to the critica& #am"ing coefficient is 3no
as #am"ing factor or #am"ing ratio.
12. 't is the ratio of ma6im!m #is"&acement of the force# +i$ration 06 ma6 to the #ef&ecti
#!e to the static force F 06o.
15. When a machine is s!""orte# $y a s"ring, the s"ring transmits the force a""&ie#
the machine to the fi6e# s!""ort or fo!n#ation. This is ca&&e# transmissi$i&ity.
17. When an !n$a&ance# machine is insta&&e# on the fo!n#ation, it "ro#!ces +i$ration
the fo!n#ation. So in or#er to "re+ent these +i$rations or to minimi9e the transmissi
of forces to the fo!n#ation, +i$ration iso&ation is im"ortant.
18. The materia&s !se# for +i$ration iso&ation are "a#s of r!$$er, fe&t or cor3 an# meta
s"rings.
1:. The f!nction of a go+ernor is to reg!&ate the mean s"ee# of an engine, hen the
are +ariations in the &oa#.
1;. The sensiti+eness is #efine# as the ratio of the #ifference $eteen the ma6im!m a
minim!m e%!i&i$ri!m s"ee#s to the mean e%!i&i$ri!m s"ee#.
1
-
8/12/2019 Answer Key Dynamics of Machinery
3/15
ANSWER KEY: PART-B
21)
-
8/12/2019 Answer Key Dynamics of Machinery
4/15
22)
-
8/12/2019 Answer Key Dynamics of Machinery
5/15
-
8/12/2019 Answer Key Dynamics of Machinery
6/15
23)
-
8/12/2019 Answer Key Dynamics of Machinery
7/15
24)
-
8/12/2019 Answer Key Dynamics of Machinery
8/15
25)
-
8/12/2019 Answer Key Dynamics of Machinery
9/15
-
8/12/2019 Answer Key Dynamics of Machinery
10/15
26)
When the rotation of the rotor is c&oc3ise hen &oo3ing from the &eft 0 i.e. rear en# or stean# hen the $o is rising 0i.e. "itching is !"ar#, then the reacti+e gyrosco"ic co!"&e acts in tc&oc3ise #irection hich ten#s to t!rn the $o toar#s right 0 i.e. toar#s star$oar#.Ans.
-
8/12/2019 Answer Key Dynamics of Machinery
11/15
27)
-
8/12/2019 Answer Key Dynamics of Machinery
12/15
-
8/12/2019 Answer Key Dynamics of Machinery
13/15
28)
-
8/12/2019 Answer Key Dynamics of Machinery
14/15
PART- B STEP MARK SPLIT UP
21) 12 MARKS
Ste" (ar3 S"&it >"
Press!re on s&i#e $ars, 2 marThr!st in the connecting ro#, 2 marTangentia& force on the cran3"in, 2 marT!rning moment on the cran3 shaft. 2 mar
22) 12 MARKS
Ste" (ar3 S"&it >"
(agnit!#es 8 marAng!&ar "ositions 8 mar
23) 12 MARKS
Ste" (ar3 S"&it >"
4ritica& #am"ing coefficient, 2 mar-am"ing factor, 2 mar*ogarithmic #ecrement, 2 marRatio of to consec!ti+e am"&it!#es 2 mar
24) 12 MARKS
Ste" (ar3 S"&it >"
Stiffness of each s"ring 5 mar-ynamicforce transmitte# to the $ase 5 marNat!ra& fre%!ency of the system 5 mar
25) 12 MARKS
Ste" (ar3 S"&it >"
(inim!m s"ee# 5 mar(a6im!m s"ee# 5 marRange of s"ee# 5 mar
-
8/12/2019 Answer Key Dynamics of Machinery
15/15
26) 12 MARKS
Ste" (ar3 S"&it >"
(a6im!m gyrosco"ic co!"&e 5 mar(a6im!m ang!&ar acce&eration of the shi" #!ring "itching, 5 mar-irection 5 mar
27) 12 MARKS
?ase# on the com"&etion of the #eri+ation, mar3 i&& $e aar#e#
28) 12 MARKS
Ste" (ar3 S"&it >"
(a6im!m f&!ct!ation of energy 8 mar(ass of the f&yhee& 8 mar
top related