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sm9 48

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PROBLEM (9.48) A link with a T cross section is loaded as shown in Fig. P9.48.
Determine at section A-B
(a) The maximum stress.
(b) The location of the neutral axis.
SOLUTION
y
B
y
20
B
M
47
P
yo
P=48
70
A
20 mm
C
z
10
y
A
60
70 × 20(45) + 60 ×10(5)
= 33 mm
70 × 20 + 60 × 10
y 0 = 20 + y = 53 mm
y=
A = 20 × 70 + 60 × 10 = 2 × 10 3 mm 3
20(70)3
60(10)3
+ 20 × 70(12) 2 +
+ 60 × 10(28) 2
12
12
6
= 10 (0.572 + 0.202 + 0.005 + 0.47)
= 1.249 × 10 6 mm 4
M = 48 × 0.053 = 2.544 kN ⋅ m
I=
P 48 ×103
(a) σ a = =
= 24 MPa
A 2 × 10−3
Mc −2544(0.047)
(σ b ) B =
=
= −95.7 MPa
I
1.249 ×10−6
33
= 67.2 MPa
(σ b ) A = 95.7
47
σ A = 24 + 67.2 MPa
σ A = 24 + 67.2 = 91.2 MPa
σ B = 24 − 95.7 = −71.7 MPa
Continued on next slide
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(b) Apply Eq.(9.13):
2544 yn
P Myn
= 24 ×106 −
0= −
A
I
1.249 × 10−6
y n = 0.0118 m = 11.8 mm
σb
B
N.A
x
yn
A
σ
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