sm7 82

________________________________________________________________________
PROBLEM (7.82) Design a rectangular cantilever beam of constant strength and width b, to
support a uniformly distributed load of intensity w (Fig. P7.82).
Assumption: Only the normal stresses owing to the bending need be considered; the allowable
stress is all
σ
.
SOLUTION
w
wL
L
wL2/2
y
x
Equation (7.31) becomes, at a distance x:
22
2
6all
bh wx
σ
= (1)
At the fixed end (
x
L= and 0 hh
=
):
22
02
6all
bh wL
σ
= (2)
Divide Eq. (1) by Eq. (2),
222
0
2Lxhh = or 0
x
hh
L
=
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