Module 4 Activity No. 3
Module 4 Activity No. 3
Module 4 Activity No. 3
3
Exercises Problem on Shafts
A round steel shaft transmits 50 HP at 150 rpm and subjected to loadings as shown.
What minimum diameter is acceptable if the shaft weight is 10 lb/ft?
a. For an allowable stress for flexure and shear are 6 ksi & 8 ksi respectively;
b. For commercial shaft with keyway; gradually applied load;
c. For AISI C1095 normalized steel; suddenly applied load with minor shock and
d. For AISI C1030 as rolled steel; gradually applied load. Use ASME Code with
keyway
Draw the load, shear and moment diagrams, vertical and horizontal components.
Solution:
P=50 HP
n=150 rpm
lb
W s=10 ¿
ft
nT
P=
63025
150 ( T )
50 HP=
63025
T =21008.33 lb .∈¿
2000 cos (30) 2000 cos (30) 1650 cos( 45)
22
7 7 8
22
R1 R2
M R 2=0
0=( 1650 cos ( 45 ) ) ( 8 )−( 2000 cos ( 30 ) ) ( 7 ) −36.67 ( 14 )− ( 2000 cos ( 30 ) ) ( 29 ) + R1 ( 36 )
R1=1487.04 lb
*for shear
v1 =1487.04
v1 a =1487.04−10 ( 127 )=1481.21
v a=1481.21−( 2000 cos ( 30 ) )=−250.85
v ab =−250.85−10
22
12 ( )
=−269.18
−250.85
−269.18
−2001.23 −2007.06
*for moment
1
M a= ( 1487.04+ 1481.21) ( 7 ) =10388.88lb .∈¿
2
1
M b=10388.88+ (−250.85−269.18 ) ( 22 )=4668.55 lb .∈¿
2
1
M 2=4668.55+ (−2001.23−2007.06 ) ( 7 ) =−9360.47 lb.∈¿
2
1
M c =−9360.47+ (1173.40+1166.73 )( 8 )=0
2
10388.88
4668.55
−9360.47
22
7 7 8
R1 R2
M R =0
1
M R =0
2
0=( 1650 sin ( 45 ) ) ( 8 ) −( 2000 sin (30 ) ) ( 7 )−( 2000 sin ( 30 ) ) ( 29 ) + R1 (36 )
R1=740.73 lb
*for shear
v1 =740.73
v a=740.73−( 2000sin ( 30 )) =−259.27
v b=−259.27−( 2000 sin ( 30 ) )=−1259.27
v 2=−1259.27+2426=1166.73
v c =1166.73−( 1650 sin ( 45 ) )=0
1166.73
740.73
−259.27
−1259.27
*for moment
M a=( 740.73 ) ( 7 ) =5185.11lb .∈¿
M b=5185.11−259.27 ( 22 )=−518.83 lb .∈¿
M 2=−518.83−1259.27 (7 )=−9333.72lb.∈¿
M c =−9333.72+1166.73 ( 8 ) =0
5185.11
−518.83
M =√ ¿ ¿ −9333.72
M a= √ ¿ ¿
M a=11 610.95 lb.∈¿
M b= √ ¿ ¿
M b=4 695.29 lb.∈¿
M 2=√ ¿ ¿
M 2=13 218.80 lb.∈¿
*use higher moment value
M =13 218.80 lb.∈¿
a.) For an allowable stress for flexure and shear are 6 ksi & 8 ksi respectively;
τ d=8 000 psi
σ d=6 000 psi
K s =K m=1∗no load type given
16
τ d= 3
¿
πD
16
8 000 psi= 3
¿
πD
D=2.51∈¿
32
σ d= ¿
π D3
32
6 000 psi= 3
¿
πD
7
D=3.18∈¿ 3
16
16
τ d= ¿
π D3
16
6 000 psi= 3
¿
πD
15
D=2.91∈¿ 2
16
32
σ d= ¿
π D3
32
12 000 psi= 3
¿
πD
D=2.74∈¿
c.) For AISI C1095 normalized steel; suddenly applied load with minor shock.
K s =1.5 ; K m =2
σ y =80 000 psi
FS=3
16
τ d= 3
¿
πD
16
13 333.33 psi= 3
¿
πD
15
D=2.5=2
16
d.) For AISI C1030 as rolled steel; gradually applied load. Use ASME Code with
keyway
K s =1; K m=1.5
16
τ d= ¿
π D3
16
14 400 ( 0.75 )= ¿
π D3
7
D=2.39=2
16