Calculators/Sakrekenaars:
Requirements for this paper/Benodigdhede vir hierdie vraestel:
Answer scripts/
Antwoordskrifte:
X
Yes/Ja
Other resources/Ander hulpmiddels:
Multi-choice cards (A5)/
Multikeusekaarte (A5):
Attendance slips (Fill-in paper)/
Presensiestrokies (Invulvraestel):
Multi-choice cards (A4)/
Multikeusekaarte (A4):
Scrap paper/
Rofwerkpapier:
Graph paper/
Grafiekpapier:
Type of assessment/
Tipe assessering:
Assessment test
Assesseringstoets
Paper/Vraestel 1
Qualification/ B.ING
Kwalifikasie:
Module code/
Modulekode:
INGM225
Duration/
Tydsduur:
1½ hour
1½ uur
Module description/
Modulebeskrywing:
Strength of Materials I
Max/
Maks:
44
Examiner(s)/
Eksaminator(e):
Prof Attie Jonker
Date/
Datum:
18/08/2022
Internal/Interne
moderator(s):
Mr Isaac Mothlakudi
Time/
Tyd:
14:30
Submission of answer scripts/Inhandiging van antwoordskrifte:
Vraag 1/ Question 1
Ordinary/Gewoon
9
1.1 Wat is die drie fundamentele vrae wat die vak Sterkteleer beantwoord? / Give the three fundamental
questions that the subject Strength of Materials answers. (3)
1.2 Watter drie hoof eienskappe beïnvloed die sterkte van ‘n komponent? / Which three main properties
influence the strength of a component? (3)
1.3 Verduidelik waarom dit moontlik is om ‘n hol as in plaas van ‘n soliede as met dieselfde afmetings te
gebruik sonder veel vermindering in wringsterkte en styfheid. / Explain why it is possible to use a hollow
shaft instead of a solid shaft with the same dimensions without much reduction in torsional strength and
stiffness. (3)
Vraag 2/ Question 2
12
‘n Ronde staaf ABC gemaak van staal is aan die een punt vas aan ‘n muur. Deel AB is 700 mm lank en het ‘n
diameter van 4 mm. Deel BC is 300 mm lank en het ‘n diameter van 2 mm. ‘n Krag van 100 N word by C
aangewend. / A round bar ABC is made of steel. It is fixed to a wall at side A. A force of 100 N is applied at C.
Part AB is 700 mm long and has a diameter of 4 mm. Part BC is 400 mm long and has a diameter of 2 mm.
Esteel = 200 GPa. Vloeispanning is: / Yield Stress is: σy = 200 MPA. (vrae op volgende bladsy / questions on
next page).
INGM225
1/5
2.1 Bereken die spanning in AB / Calculate the stress in AB. (5)
2.2 Bereken die totale verlenging van die staaf. / Calculate the total elongation of the bar. (5)
2.3 Is die vervorming in die elastiese gebied of plastiese gebied? / Is the strain in the elastic or plastic region?
(2)
Vraag 3/ Question 3
10
Twee silindriese staaf segmente word solied vasgeheg aan mure sodat daar ‘n gaping van 0.254 mm tussen
die stawe is by ‘n T1=60°C. Elke staaf het ‘n deursnee van 31.75 mm. Bepaal die gemiddelde normale spanning
in elke staaf as T2=400°C is. Bereke nook die nuwe lengte van die aluminium (2014-T6) gedeelte. / The two
cylindrical rod segments are fixed to rigid walls such that there is a gap of 0.254 mm between them when
T1=60°C. Each rod has a diameter of 31.75 mm. Determine the average normal stress in each rod if T2=400°C,
and also calculate the new length of the aluminum (2014-T6) segment.
Red Brass
Vraag 4/ Question 4
5
’n Wringkrag van 200 N.m word op die kwart-van-‘n-sirkel buis toegepas. As die wanddikte 2.5 mm is, bepaal
die gemiddelde skuifspanning in die buis. / A torque of 200 N.m is applied to the quarter-of-a-circle tube. If
the wall thinkness is 2.5 mm, determine the average shear stress in the tube.
·
Starts here
Alge
Vraag 5/ Question 5
8
Bepaal die deursnee van die dryfas van 'n bakkie met die volgende spesifikasies: Enjin = 290 kW, maksimum
spoed = 220 km/h, wieldeursnee = 800 mm, ewenaarverhouding = 1:2, Veiligheidsfaktor = 3, σy = 110 Mpa. /
Determine the diameter of the driveshaft of a bakkie with the following specifications: Engine = 290 kW,
maximum speed = 220 km/h, wheel diameter = 800 mm, diff ratio = 1:2, Safety Factor = 3, σy = 110 Mpa.
TOTAL/TOTAAL: 44
INGM225
2/5
Sterk
genoey Strong
Stiff
styf genoey ~
Stabiel
genoeg
~
3
~
Stable
~
Krayte/las/ loading
~
Afmetings
~
Material
~
/ Material properties
Dimensies /
3
L
e
&
pytman
i
Emin
(max
Torque/Shear stress is high
At center
it is
zero/less
at the
w
extreme outside
.
3
SAB
formula
FERAs
=
~
(100) (0 4)
.
~
.
(π(2800)2)(2009)
-
0
0 00002785212 m
.
..
SAB
0
.
mm
02785
:
RA
=
S
(π(280)2)(2009)
=
-
=
F
-
Sub
(100) (0 7)
-
Sc
Stotual
.
=
SBC
0 09151
.
00006366198m
.
=0 06366
.
mm
~
mm
↳ 100 N
100N
A
B
C
SFAB
..
~
S
100
=
.
=
.
A
Elastic
region
(igod" S
SFic=
7 96
=25 13 > /
RAN
OAB=
200 E6
200
-
6 28
.
:.
Elastic
W
Z
region
↑(2)
2
~=
7 96
.
MPa
12
:
Fi
a
7
I
0
E
=
=
18E
101
6/°
a
GPa
=
-
23E
=
=
73 1
.
6/
2
0
si
but
Fr
-
GPa
is
F,
:
=
Fz
Si
S,
~
( E + STh]+(EE
2
-
F
,
(1
+
,
,
+
82
=
0
000254
.
.
w
+
225Th]
E]
.
=
0
000254
.
0
000254-2 , ATL-4uATL
.
0
.
000254
-(18E -6) (340) (0 3048)
0
2 a
.
.
00004647
434 94kN
=
82
0
.
0465
3
mm
~
:
434938 7143N
.
.
↑2019
,
-
-
...
=
(23= 6)(340) (0 1524)
(23E b) (340)(0 1524)
-
.
0 3048
=
+
=
Sub
=
.
..
W
.
( x (I i)(73 129)
.
~
F
Gathe
+
(- 434938 7143)(0 1524)
=
-
.. -F ,
~
E
=
S
~
New
length
=
152 4465 mm
.
.
~
Fi
..
O,
=
As
=
02
7
-
..
0,
=
↳are
549 35
.
MPa
10
Side Note
can't start
can't start
:
here
here
*
&
..
.
·
must
start here
of
:
1 25
.
.
↳
1
.
25 8
...
1678
:.
,25
new
radius
Am
48 75-1 25 -1 7678
=
.
=
.
=
.
E )45 ! )
45
.
Tary=
73223304703mmh
=
zAm
24)(0
.
0016426 ...
e
~
=0 00164261089 m
.
:
Targ= 24
.
MP
35
6 25mm
.
..
of Am
44(8)
2
i
( 10
=
:
Z
=
0
..
+
Targ=
.
001684924
2 r
e
Am
=
=0
.
245)(0 001684924)
.
:
Targ=
23 74
.
MP
44( :8) +,)48 !
-
=
zAm
22)(0001800
Targ=
23 81
.
Z
0
...
Targ=
.
001649763442
=
245)(0 00164976344(
.
:
r
za
We
MP
...
.
=
=
e
3 535533
+
:
Tary=
:.
~
001680015m2
We
=
r
of Am
:
za
)
Targ= 24 25
.
MP
S
<V 220km/h
=
=
61 i m/s
.
*
Allowable 1
Ty
O
=
800mm
=
0
.
win
shaft
ssMP
=
=
Ty
=
110 MPa
8 m
SF
*
:
..
:
3
=
=
18 3
=
.
MP
:
=
MPa
36 6
.
2
2
Power
*
:
L
7
diff ratio
=
:
1: 2
P
I
290000
:. T
V
=
wr
I
... W2
=
... W,
we
T(305 5)
.
949 09
=
.
N.m
.
=
r
w
=
2 x 152 7
Vt
=
T
=
30s .s
radis
~
*
of driveshaft
:
a.
=
=
:. W
,
0
.
8/2
152 7
.
Tc
radis
18 3E6
=
=
.
..
C
0
..
=
=
S
I
194909
0
0
.
.
~
36 6E6
=
.
032061376
m
064122753
m
~
64
=
of
:
:
.
65
..
12 mm
mm
~
c
=
=
19
0
0
025447131
.
.
m
050894263m
50 89mm
=
.
of
:
50/51
mm