Tutorial No.
UNIVERSITY OF BAHRAIN
College of Engineering
MENG 371 Mechanics of Materials
Q.1) The wide-flange beam shown is made
of a high-strength, low-alloy steel for which
σu = 450 MPa. Using a factor of safety of
3.0, determine the largest couple that can be
applied to the beam when it is bent about the
y axis. Neglect the effect of fillets.
Solution:
= ℎ = × 18 × (250) = 23.438 × 10
= ℎ = × 324 × (10) = 27 × 10
= = 23.438 × 10
= + + = 23.438 × 10 × 2 + 0.027 × 10 = 46.903 × 10
= 46.903 × 10
= =125 mm = 0.125 m
×
= .
= = 150 × 10
× . ×
= → = = .
= 56.3 × 10 . = 56.3 .
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Q 2) For the couple
shown acts in a vertical
plane, determine the
stress at (a) point A, (b)
point B.
Solution:
For rectangle = ℎ
For cross sectional area
= + + = × 2 × (1.5) + × 2 × (5.5) + × 2 × (1.5)
= 28.854
( )( . )
(a) = 2.75 → =− =− .
= −2.38
( )( . )
(b) = 0.75 → =− =− .
= −0.65
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A vertical 4.80-kN load is
applied as shown on a wooden post of rectan- gular
cross section, 80 by 120 mm (Fig. 4.65). (a)
Determine the stress at points A, B, C, and D. (b)
Locate the neutral axis of the cross section.
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