PROBLEM 1.1
Two solid cylindrical rods AB and BC are welded together at B and
loaded as shown. Knowing that the average normal stress must not
exceed 175 MPa in rod AB and 150 MPa in rod BC, determine the
smallest allowable values of d1 and d2.
SOLUTION
(a)
Rod AB
P = 40 + 30 = 70 kN = 70 × 103 N
σ AB =
d1 =
(b)
P
=
AAB
P
4P
=
2
d
π d12
4 1
π
4P
=
πσ AB
(4)(70 × 103 )
= 22.6 × 10−3 m
π (175 × 106 )
d1 = 22.6 mm 
Rod BC
P = 30 kN = 30 × 103 N
σ BC =
d2 =
P
=
ABC
4P
πσ BC
P
4P
=
2
d
π d 22
4 2
π
=
(4)(30 × 103 )
= 15.96 × 10−3 m
π (150 × 106 )
d 2 = 15.96 mm 
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